PROGRAMMABLE FREQUENCY DIVIDER FOR LOCAL OSCILLATOR GENERATION

• US 20140266471A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhu, Yunliang, Tang, Yiwu
• Granted Patent: US 9,106,234 B2
• Time in Patent Office: Days
• US Class Current: 331/16
• CPC Class Codes: H03B 19/14 by means of a semiconductor device
• CPC Class Codes: H03B 27/00 Generation of oscillations providing a plurality of outputs of the same frequency but differing in phase, other than merely two anti-phase outputs
• CPC Class Codes: H03K 3/0315 Ring oscillators
• CPC Class Codes: H03K 3/0322 with differential cells
• CPC Class Codes: H03L 7/00 Automatic control of frequency or phase; Synchronisation
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H03L 7/24 using a reference signal directly applied to the generator
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A method, an apparatus, and a computer program product are provided. The apparatus generates LO signals. The apparatus includes a LO generator module and an injection signal generator module coupled together. The LO generator module has a plurality of LO outputs and a plurality of injection signal inputs. The LO module is configured to generate the LO signals on the LO outputs based on injection signals received on the injection signal inputs. The injection signal generator module has a plurality of LO inputs and a plurality of injection signal outputs. The LO inputs are coupled to the LO outputs. The injection signal outputs are coupled to the injection signal inputs. The injection signal generator module is configured to generate injection signals on the injection signal outputs based on the LO signals received on the LO inputs and based on a received VCO signal.

Claims

1. An apparatus for generating local oscillator signals, comprising:

a local oscillator generator module having a plurality of local oscillator outputs and a plurality of injection signal inputs, the local oscillator module being configured to generate the local oscillator signals on the local oscillator outputs based on injection signals received on the injection signal inputs; and

an injection signal generator module coupled to the local oscillator generator module, the injection signal generator module having a plurality of local oscillator inputs and a plurality of injection signal outputs, the local oscillator inputs being coupled to the local oscillator outputs, the injection signal outputs being coupled to the injection signal inputs, the injection signal generator module being configured to generate injection signals on the injection signal outputs based on the local oscillator signals received on the local oscillator inputs and based on a received voltage controlled oscillator (VCO) signal.

2. The apparatus of claim 1, wherein the injection signal generator module is programmable to provide at least three different sets of injection signals.

3. The apparatus of claim 1, wherein the local oscillator generator module comprises n delay stages and n injection signal inputs, each of the n injection signal inputs being between a different pair of delay stages, each of the n injection signal inputs being independently controlled by the injection signal generator module.

4. The apparatus of claim 1, wherein the local oscillator generator module comprises a plurality of delay stages, and the apparatus further comprises a tuning module coupled to the local oscillator generator module, the tuning module being configured to tune a frequency of the local oscillator signals.

5. The apparatus of claim 4, wherein the tuning module is configured to adjust a capacitance of each of the delay stages in order to tune the frequency of the local oscillator signals.

6. The apparatus of claim 4, wherein the tuning module is configured to determine a frequency of the local oscillator signals, to compare the determined frequency to a target frequency of the local oscillator signals, and to adjust the frequency stepwise of the local oscillator signals until a difference between the frequency and the target frequency is less than a threshold.

7. The apparatus of claim 1, further comprising a division ratio selection module configured to select a division ratio of a plurality of available division ratios and to provide the selected division ratio to the injection signal generator module, wherein the injection signal generator module is further configured to generate the injection signals based on the received selected division ratio.

8. The apparatus of claim 7, wherein the division ratio selection module is configured to select the division ratio from one of at least three available division ratios.

9. The apparatus of claim 8, wherein the at least three available division ratios include a division ratio of approximately 3, a division ratio of approximately 4, and division ratio of approximately 5.

10. The apparatus of claim 8, wherein the injection signal generator module and the local oscillator generator module together are configured to divide a frequency of the received VCO signal by a division ratio approximately equal to 3, 4, or 5 based on input from the division ratio selection module, and to provide the local oscillator signals at each of the divided frequencies separately based on the input from the division ratio selection module.

11. The apparatus of claim 1, further comprising a VCO module configured to provide the VCO signal to the injection signal generator module.

12. The apparatus of claim 1, wherein the injection signal generator module is configured to receive the VCO signal at a frequency approximately equal to three times a desired frequency of the local oscillator signals.

13. The apparatus of claim 12, wherein based on the received VCO signal, the injection signal generator module is configured to provide a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to a, the second injection signal having a phase approximately equal to α

, the third injection signal having a phase approximately equal to α

+π

, and the fourth injection signal having a phase approximately equal to α

+π

.

14. The apparatus of claim 13, wherein based on the received injection signals, the local oscillator generator module is configured to generate the local oscillator signals at a frequency approximately equal to one half of the frequency of the injections signals.

15. The apparatus of claim 13, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

16. The apparatus of claim 1, wherein the injection signal generator module is configured to receive the VCO signal at a frequency approximately equal to four times a desired frequency of the local oscillator signals.

17. The apparatus of claim 16, wherein based on the received VCO signal, the injection signal generator module is configured to provide a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal, the first injection signal having a phase approximately equal to α

, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to α

, and the fourth injection signal having a phase approximately equal to α

+π

.

18. The apparatus of claim 17, wherein based on the received injection signals, the local oscillator generator module is configured to generate the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

19. The apparatus of claim 17, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

20. The apparatus of claim 1, wherein the injection signal generator module is configured to receive the VCO signal at a frequency approximately equal to five times a desired frequency of the local oscillator signals.

21. The apparatus of claim 20, wherein based on the received VCO signal, the injection signal generator module is configured to provide a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to a, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to a, and the fourth injection signal having a phase approximately equal to α

+π

.

22. The apparatus of claim 21, wherein based on the received injection signals, the local oscillator generator module is configured to generate the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

23. The apparatus of claim 21, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

24. The apparatus of claim 1, wherein the received VCO signal comprises a first VCO signal and a second VCO signal;

the local oscillator outputs comprise a first local oscillator output signal and a second local oscillator output signal;

the injection signal generator module comprises a first transistor and a second transistor;

an injection signal output of the plurality of injection signal outputs is coupled to a drain of the first transistor and to a drain of the second transistor;

a source of the first transistor is coupled to the first VCO signal; and

a source of the second transistor is coupled to the second VCO signal.

25. The apparatus of claim 24, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

26. The apparatus of claim 24, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.

27. The apparatus of claim 24, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

28. The apparatus of claim 24, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.

29. A method of generating local oscillator signals, comprising:

generating, in a local oscillator generator module, the local oscillator signals based on received injection signals; and

generating, in an injection signal generator module, the injection signals based on the local oscillator signals and a received voltage controlled oscillator (VCO) signal.

30. The method of claim 29, wherein the injection signal generator module is programmable to provide at least three different sets of injection signals.

31. The method of claim 29, wherein the local oscillator generator module comprises n delay stages and n injection signal inputs, each of the n injection signal inputs being between a different pair of delay stages, each of the n injection signal inputs being independently controlled by the injection signal generator module.

32. The method of claim 29, wherein the local oscillator generator module comprises a plurality of delay stages, and the method further comprises tuning, in a tuning module coupled to the local oscillator generator module, a frequency of the local oscillator signals.

33. The method of claim 32, further comprising adjusting, in the tuning module, a capacitance of each of the delay stages in order to tune the frequency of the local oscillator signals.

34. The method of claim 32, wherein the tuning comprises:

determining a frequency of the local oscillator signals;

comparing the determined frequency to a target frequency of the local oscillator signals; and

adjusting the frequency stepwise of the local oscillator signals until a difference between the frequency and the target frequency is less than a threshold.

35. The method of claim 29, further comprising:

selecting, in a division ratio selection module, a division ratio of a plurality of available division ratios; and

providing the selected division ratio to the injection signal generator module,

wherein the injection signals are generated based on the received selected division ratio.

36. The method of claim 35, wherein the division ratio is selected from one of at least three available division ratios.

37. The method of claim 36, wherein the at least three available division ratios include a division ratio of approximately 3, a division ratio of approximately 4, and division ratio of approximately 5.

38. The method of claim 36, further comprising:

dividing, in the injection signal generator module and the local oscillator generator module, a frequency of the received VCO signal by a division ratio approximately equal to 3, 4, or 5 based on input from the division ratio selection module; and

providing the local oscillator signals at each of the divided frequencies separately based on the input from the division ratio selection module.

39. The method of claim 29, further comprising providing, in a VCO module, the VCO signal to the injection signal generator module.

40. The method of claim 29, further comprising receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to three times a desired frequency of the local oscillator signals.

41. The method of claim 40, further comprising providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to a, the second injection signal having a phase approximately equal to a, the third injection signal having a phase approximately equal to α

+π

, and the fourth injection signal having a phase approximately equal to α

+π

.

42. The method of claim 41, further comprising generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one half of the frequency of the injections signals.

43. The method of claim 41, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

44. The method of claim 29, further comprising receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to four times a desired frequency of the local oscillator signals.

45. The method of claim 44, further comprising providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal, the first injection signal having a phase approximately equal to α

, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to a, and the fourth injection signal having a phase approximately equal to α

+π

.

46. The method of claim 45, further comprising generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

47. The method of claim 45, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

48. The method of claim 29, further comprising receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to five times a desired frequency of the local oscillator signals.

49. The method of claim 48, further comprising providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to a, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to a, and the fourth injection signal having a phase approximately equal to α

+π

.

50. The method of claim 49, further comprising generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

51. The method of claim 49, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

52. The method of claim 29, wherein the received VCO signal comprises a first VCO signal and a second VCO signal;

the local oscillator generator module has a plurality of local oscillator outputs;

the injection signal generator module has a plurality of injection signal inputs;

the local oscillator outputs comprise a first local oscillator output signal and a second local oscillator output signal;

the injection signal generator module comprises a first transistor and a second transistor;

an injection signal output of the plurality of injection signal outputs is coupled to a drain of the first transistor and to a drain of the second transistor;

a source of the first transistor is coupled to the first VCO signal; and

a source of the second transistor is coupled to the second VCO signal.

53. The method of claim 52, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

54. The method of claim 52, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.

55. The method of claim 52, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

56. The method of claim 52, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.

57. An apparatus for generating local oscillator signals, comprising:

means for generating, in a local oscillator generator module, the local oscillator signals based on received injection signals; and

means for generating, in an injection signal generator module, the injection signals based on the local oscillator signals and a received voltage controlled oscillator (VCO) signal.

58. The apparatus of claim 57, wherein the injection signal generator module is programmable to provide at least three different sets of injection signals.

59. The apparatus of claim 57, wherein the local oscillator generator module comprises n delay stages and n injection signal inputs, each of the n injection signal inputs being between a different pair of delay stages, each of the n injection signal inputs being independently controlled by the injection signal generator module.

60. The apparatus of claim 57, wherein the local oscillator generator module comprises a plurality of delay stages, and the apparatus further comprises means for tuning, in a tuning module coupled to the local oscillator generator module, a frequency of the local oscillator signals.

61. The apparatus of claim 60, further comprising means for adjusting, in the tuning module, a capacitance of each of the delay stages in order to tune the frequency of the local oscillator signals.

62. The apparatus of claim 60, wherein the means for tuning is configured to:

determine a frequency of the local oscillator signals;

compare the determined frequency to a target frequency of the local oscillator signals; and

adjust the frequency stepwise of the local oscillator signals until a difference between the frequency and the target frequency is less than a threshold.

63. The apparatus of claim 57, further comprising:

means for selecting, in a division ratio selection module, a division ratio of a plurality of available division ratios; and

means for providing the selected division ratio to the injection signal generator module,

wherein the injection signals are generated based on the received selected division ratio.

64. The apparatus of claim 63, wherein the division ratio is selected from one of at least three available division ratios.

65. The apparatus of claim 64, wherein the at least three available division ratios include a division ratio of approximately 3, a division ratio of approximately 4, and division ratio of approximately 5.

66. The apparatus of claim 64, further comprising:

means for dividing, in the injection signal generator module and the local oscillator generator module, a frequency of the received VCO signal by a division ratio approximately equal to 3, 4, or 5 based on input from the division ratio selection module; and

means for providing the local oscillator signals at each of the divided frequencies separately based on the input from the division ratio selection module.

67. The apparatus of claim 57, further comprising means for providing, in a VCO module, the VCO signal to the injection signal generator module.

68. The apparatus of claim 57, further comprising means for receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to three times a desired frequency of the local oscillator signals.

69. The apparatus of claim 68, further comprising means for providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to α

, the second injection signal having a phase approximately equal to α

, the third injection signal having a phase approximately equal to α

+π

, and the fourth injection signal having a phase approximately equal to α

+π

.

70. The apparatus of claim 69, further comprising means for generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one half of the frequency of the injections signals.

71. The apparatus of claim 69, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

72. The apparatus of claim 57, further comprising means for receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to four times a desired frequency of the local oscillator signals.

73. The apparatus of claim 72, further comprising means for providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal, the first injection signal having a phase approximately equal to α

, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to a, and the fourth injection signal having a phase approximately equal to α

+π

.

74. The apparatus of claim 73, further comprising means for generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

75. The apparatus of claim 73, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

76. The apparatus of claim 57, further comprising means for receiving, in the injection signal generator module, the VCO signal at a frequency approximately equal to five times a desired frequency of the local oscillator signals.

77. The apparatus of claim 76, further comprising means for providing, based on the received VCO signal and in the injection signal generator module, a first injection signal, a second injection signal, a third injection signal, and a fourth injection signal at a frequency approximately equal to the frequency of the VCO signal minus a frequency of the local oscillator signals, the first injection signal having a phase approximately equal to α

, the second injection signal having a phase approximately equal to α

+π

, the third injection signal having a phase approximately equal to α

, and the fourth injection signal having a phase approximately equal to α

+π

.

78. The apparatus of claim 77, further comprising means for generating, based on the received injection signals and in the local oscillator generator module, the local oscillator signals at a frequency approximately equal to one fourth of the frequency of the injections signals.

79. The apparatus of claim 77, wherein the local oscillator generator module comprises four delay stages coupled in series, the four delay stages comprising a first delay stage coupled in series between a second delay stage and a fourth delay stage, the second delay stage coupled in series between the first delay stage and a third delay stage, the third delay stage coupled in series between the second delay stage and the fourth delay stage, the fourth delay stage coupled in series between the third delay stage and the first delay stage, wherein the first injection signal is applied to a first injection signal input between the first delay stage and the second delay stage, the second injection signal is applied to a second injection signal input between the second delay stage and the third delay stage, the third injection signal is applied to a third injection signal input between the third delay stage and the fourth delay stage, and the fourth injection signal is applied to a fourth injection signal input between the fourth delay stage and the first delay stage.

80. The apparatus of claim 57, wherein the received VCO signal comprises a first VCO signal and a second VCO signal;

the local oscillator generator module has a plurality of local oscillator outputs;

the injection signal generator module has a plurality of injection signal inputs;

the local oscillator outputs comprise a first local oscillator output signal and a second local oscillator output signal;

the injection signal generator module comprises a first transistor and a second transistor;

an injection signal output of the plurality of injection signal outputs is coupled to a drain of the first transistor and to a drain of the second transistor;

a source of the first transistor is coupled to the first VCO signal; and

a source of the second transistor is coupled to the second VCO signal.

81. The apparatus of claim 80, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

82. The apparatus of claim 80, wherein a gate of the first transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.

83. The apparatus of claim 80, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected.

84. The apparatus of claim 80, wherein a gate of the first transistor is coupled to the second local oscillator output signal when a division ratio of three is selected, to a circuit ground when a division ratio of four is selected, and to the second local oscillator output signal when a division ratio of five is selected;

and a gate of the second transistor is coupled to the first local oscillator output signal when a division ratio of three is selected, to a supply voltage when a division ratio of four is selected, and to the first local oscillator output signal when a division ratio of five is selected.