Wideband temperature compensated resonator and wideband VCO

• US 8,253,506 B2
• Filed: 10/05/2010
• Issued: 08/28/2012
• Est. Priority Date: 10/05/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Liu, Li, Narathong, Chiewcharn
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US12/897,918
• Publication Number:
  US 20120081188A1
• Time in Patent Office: 693 Days
• Field of Search: 331/16, 331/17, 331/36.C, 331/117.FE, 331/117.R, 331/167, 331/176, 331/177.V
• US Class Current: 331/177.V
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/1212 the amplifier comprising a pair of transistors, wherein an output terminal of each being connected to an input terminal of the other, e.g. a cross coupled pair
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03L 1/023 by using voltage variable capacitance diodes
• CPC Class Codes: H03L 1/025 and a memory for digitally storing correction values
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop
• CPC Class Codes: H03L 7/104 using an additional signal from outside the loop for setting or controlling a parameter in the loop H03L7/107, H03L7/12 take precedence
• CPC Class Codes: H03L 7/1976 using a phase accumulator for controlling the counter or frequency divider

Abstract

A resonator of a VCO includes a fine tuning main varactor circuit, an auxiliary varactor circuit, and a coarse tuning capacitor bank circuit coupled in parallel with an inductance. The main varactor circuit includes a plurality of circuit portions that can be separately disabled. Within each circuit portion is a multiplexing circuit that supplies a selectable one of either a fine tuning control signal (FTAVCS) or a temperature compensation control signal (TCAVCS) onto a varactor control node within the circuit portion. If the circuit portion is enabled then the FTAVCS is supplied onto the control node so that the circuit portion is used for fine tuning. If the circuit portion is disabled then the TCAVCS is supplied onto the control node so that the circuit portion is used to combat VCO frequency drift as a function of temperature. How the voltage of the TCAVCS varies with temperature is digitally programmable.

Claims

1. An apparatus comprising:

a first node;

a second node;

a first signal input conductor;

a second signal input conductor;

a main varactor circuit comprising;

a first main varactor circuit portion comprising;

a first varactor having a first lead and a second lead, wherein the first lead of the first varactor is coupled to the first node;

a second varactor having a first lead and a second lead, wherein the first lead of the second varactor is coupled to the second node, and wherein the second lead of the second varactor is coupled to the second lead of the first varactor at a first control node; and

a first analog multiplexing circuit that couples a selected one of the first signal input conductor and the second signal input conductor to the first control node;

an auxiliary varactor circuit coupled between the first node and the second node;

a first temperature compensation voltage generating circuit having an output lead coupled to the second signal input conductor; and

a second temperature compensation voltage generating circuit having an output lead coupled to the auxiliary varactor circuit.

2. The apparatus of claim 1, wherein a first analog control signal is present on the first signal input conductor, and wherein a second analog control signal is present on the second signal input conductor.

3. The apparatus of claim 2, wherein the first analog control signal is a fine tuning control signal received from a loop filter, and wherein the second analog control signal is a signal that varies as a function of temperature.

4. The apparatus of claim 1, wherein the first temperature compensation voltage generating circuit supplies a first Temperature Compensation Analog Voltage Control Signal (TCAVCS) onto the second signal input conductor, wherein the first TCAVCS has a voltage that varies as a function of temperature.

5. The apparatus of claim 4, wherein the voltage of the first TCAVCS varies as a function of temperature in a first way if a digital control value received by the first temperature compensation voltage generating circuit has a first digital value, whereas the voltage of the first TCAVCS varies as a function of temperature in a second way if the digital control value received by the first temperature compensation voltage generating circuit has a second digital value.

6. The apparatus of claim 1, wherein the main varactor circuit further comprises:

a second main varactor circuit portion comprising;

a third varactor having a first lead and a second lead, wherein the first lead of the third varactor is coupled to the first node;

a fourth varactor having a first lead and a second lead, wherein the first lead of the fourth varactor is coupled to the second node, and wherein the second lead of the fourth varactor is coupled to the second lead of the third varactor at a second control node; and

a second analog multiplexing circuit that couples a selected one of the first signal input conductor and the second signal input conductor to the second control node.

7. The apparatus of claim 6, wherein the apparatus is a Voltage Controlled Oscillator (VCO) that receives a multi-bit digital tuning word, wherein a first digital bit of the multi-bit digital tuning word controls the first analog multiplexing circuit, and wherein a second digital bit of the multi-bit digital tuning word controls the second analog multiplexing circuit.

8. The apparatus of claim 1, wherein the apparatus is a Voltage Controlled Oscillator (VCO) that receives a Fine Tuning Analog Voltage Control Signal (FTAVCS) from a loop filter onto the first signal input conductor.

9. The apparatus of claim 1, wherein the first lead of the first varactor is coupled to the first node by a first capacitor, and wherein the first lead of the second varactor is coupled to the second node by a second capacitor.

10. The apparatus of claim 1, wherein the first lead of the first varactor is directly connected to the first node so that the first lead of the first varactor is a part of the first node, and wherein the first lead of the second varactor is directly connected to the second node so that the first lead of the second varactor is a part of the second node.

11. The apparatus of claim 1, wherein the first analog multiplexing circuit comprises:

a first transistor operative to be conductive so that it couples the first signal input conductor to the first control node when a digital control signal has a first digital value, and operative to be nonconductive when the digital control signal has a second digital value opposite the first digital value; and

a second transistor operative to be conductive so that it couples the second signal input conductor to the first control node when the digital control signal has the second digital value, and operative to be nonconductive when the digital control signal has a first digital value.

12. The apparatus of claim 1, wherein the auxiliary varactor circuit comprises:

a first auxiliary varactor circuit portion coupled to provide a first capacitance between the first node and the second node, wherein the first capacitance varies as a function of temperature.

13. The apparatus of claim 12, wherein the auxiliary varactor circuit further comprises:

a second auxiliary varactor circuit portion coupled to provide a second capacitance between the first node and the second node, wherein the second capacitance varies as a function of temperature.

14. The apparatus of claim 13, wherein the apparatus is a Voltage Controlled Oscillator (VCO) that receives a Fine Tuning Analog Voltage Control Signal (FTAVCS) from a loop filter onto the first signal input conductor, and wherein the FTAVCS is not supplied to the first auxiliary varactor circuit portion and is not supplied to the second auxiliary varactor circuit portion.

15. The apparatus of claim 14, wherein the first auxiliary varactor circuit portion receives a first digital control bit that at least in part determines a magnitude of the first capacitance, and wherein the second auxiliary varactor circuit portion receives a second digital control bit that at least in part determines a magnitude of the second capacitance.

16. The apparatus of claim 1, wherein the auxiliary varactor circuit is coupled to provide a digitally programmable temperature dependent capacitance between the first node and the second node, wherein the auxiliary varactor circuit receives a digital control value that at least in part determines a magnitude of the digitally programmable temperature dependent capacitance.

17. The apparatus of claim 16, wherein the apparatus is a Voltage Controlled Oscillator (VCO) that receives a Fine Tuning Analog Voltage Control Signal (FTAVCS) from a loop filter onto the first signal input conductor, and wherein the FTAVCS is not supplied to the auxiliary varactor circuit.

18. The apparatus of claim 1, further comprising:

a digitally programmable coarse tuning capacitor bank circuit coupled to provide a digitally programmable capacitance between the first node and the second node.

19. The apparatus of claim 1, further comprising:

a digitally programmable coarse tuning capacitor bank circuit coupled to provide a digitally programmable capacitance between the first node and the second node, wherein the digitally programmable coarse tuning capacitor bank circuit comprises;

a first capacitor bank circuit portion that is coupled to the first node and that is coupled to the second node and that receives a first digital control bit, wherein the first digital control bit at least in part determines a first capacitance provided by the first capacitor bank circuit portion between the first and second nodes; and

a second capacitor bank circuit portion that is coupled to the first node and that is coupled to the second node and that receives a second digital control bit, wherein the second digital control bit at least in part determines a second capacitance provided by the second capacitor bank circuit portion between the first and second nodes.

20. The apparatus of claim 19, wherein the first capacitor bank circuit portion includes a first transistor that is on when the first digital control bit has a first digital value, wherein the first capacitance provided by the first capacitor bank circuit portion when the first digital control bit has the first digital value varies in a first way with temperature, wherein the first transistor is off when the first digital control bit has a second digital value opposite the first digital value, wherein the first capacitance provided by the first capacitor bank circuit portion when the first digital control bit has the second digital value varies in a second way with temperature.

21. The apparatus of claim 20, wherein the varying of the first capacitance in the second way is at least in part due to a reverse biased diode in the first capacitor bank circuit portion, wherein the first capacitor bank circuit portion receives an analog voltage control signal that at least in part determines a capacitance of the reverse biased diode.

22. The apparatus of claim 1,

wherein the first temperature compensation voltage generating circuit outputs a first Temperature Compensation Analog Voltage Control Signal (TCAVCS) to the main varactor circuit, wherein the first temperature compensation voltage generating circuit receives a first multi-bit digital value, and wherein the first multi-bit digital value determines a first programmable slope of how the first TCAVCS varies as a function of temperature, and

wherein the second temperature compensation voltage generating circuit outputs a second Temperature Compensation Analog Voltage Control Signal (TCAVCS) to the auxiliary varactor circuit, wherein the second temperature compensation voltage generating circuit receives a second multi-bit digital value, and wherein the second multi-bit digital value determines a second programmable slope of how the second TCAVCS varies as a function of temperature.

23. The apparatus of claim 22, wherein the main varactor is coupled to receive a Fine Tuning Analog Voltage Control Signal (FTAVCS) from a loop filter, and wherein the FTAVCS is not supplied to the auxiliary varactor circuit.

24. An apparatus that receives a Fine Tuning Analog Voltage Control Signal (FTAVCS) and a multi-bit digital control word, the apparatus comprising:

a main varactor circuit comprising a plurality of main varactor circuit portions that can be selectably enabled or disabled, wherein the main varactor circuit portions are coupled together in parallel between a first node and second node , wherein each of the plurality of main varactor circuit portions receives a first Temperature Compensation Analog Voltage Control Signal (TCAVCS), and wherein each of the plurality of main varactor circuit portions receives the FTAVCS;

an auxiliary varactor circuit comprising a plurality of auxiliary varactor circuit portions that can be selectably enabled or disabled, wherein the auxiliary varactor circuit portions are coupled together in parallel between the first and second nodes, wherein each of the plurality of auxiliary varactor circuit portions receives a second Temperature Compensation Analog Voltage Control Signal (TCAVCS), wherein none of the auxiliary varactor circuit portions receives the FTAVCS; and

a digitally programmable coarse tuning capacitor bank circuit comprising a plurality of capacitor bank circuit portions that can be selectably enabled or disabled, wherein the capacitor bank circuit portions are coupled together in parallel, wherein none of the plurality of capacitor bank circuit portions receives the FTAVCS, wherein the multi-bit digital control word determines how many and which of the main varactor circuit portions, the auxiliary varactor circuit portions, and the capacitor bank circuit portions are enabled.

25. The apparatus of claim 24, wherein a capacitance of any of the main varactor circuit portions that is not enabled is controlled as a function of temperature, wherein a capacitance of any of the auxiliary varactor circuit portions that is not enabled is controlled as a function of temperature, and wherein a capacitance of any of the capacitor bank circuit portions that is not enabled is controlled as a function of temperature.

26. The apparatus of claim 24, the apparatus further comprising:

a first temperature compensation voltage generating circuit that supplies the first TCAVCS to each of the main varactor circuit portions, wherein the multi-bit digital control word determines how the first TCAVCS varies with temperature;

a second temperature compensation voltage generating circuit that supplies the second TCAVCS to each of the auxiliary varactor circuit portions, wherein the multi-bit digital control word determines how the second TCAVCS supplied to the auxiliary varactor circuit portions varies with temperature; and

a third temperature compensation voltage generating circuit that supplies a third TCAVCS to each of the capacitor bank circuit portions, wherein the multi-bit digital control word determines how the third TCAVCS supplied to the capacitor bank circuit portions varies with temperature.

27. The apparatus of claim 24, wherein each of the main varactor circuit portions comprises a first varactor having a lead coupled to a control node, a second varactor having a lead coupled to the control node, and an analog multiplexing circuit coupled to supply a signal onto the control node.

28. The apparatus of claim 27, wherein the multi-bit digital control word controls the analog multiplexing circuits of the main varactor circuit portions.

29. A method comprising:

receiving a Fine Tuning Analog Voltage Control Signal (FTAVCS) onto an input conductor of a Voltage Controlled Oscillator (VCO);

generating a first Temperature Compensation Analog Voltage Control Signal (TCAVCS) having a voltage that changes as a function of temperature;

generating a second Temperature Compensation Analog Voltage Control Signal (TCAVCS) having a voltage that changes as a function of temperature;

supplying a selected one of the FTAVCS and the first TCAVCS onto a control node of a first main varactor circuit portion;

supplying a selected one of the FTAVCS and the first TCAVCS onto a control node of a second main varactor circuit portion, wherein the first and second main varactor circuit portions are coupled together in parallel between a first and second node and are parts of the VCO and

supplying a selected one of the first and the second TCAVCS to an auxiliary varactor circuit, wherein the auxiliary varactor circuit is coupled in parallel with the main varactor circuit and is a part of the VCO, wherein the auxiliary varactor circuit does not receive the FTAVCS, wherein the auxiliary varactor circuit has a digitally programmable temperature dependent variable capacitance, and wherein a multi-bit digital control word at least in part determines a magnitude of the digitally programmable temperature dependent variable capacitance.

30. The method of claim 29, further comprising:

receiving the multi-bit digital control word onto the VCO, wherein the multi-bit digital control word determines which one of the FTAVCS and the first TCAVCS is supplied onto the control node of the first main varactor circuit portion, wherein the multi-bit digital control word determines which one of the FTAVCS and the first TCAVCS is supplied onto the control node of the second main varactor circuit portion; and

wherein the multi-bit digital control word determines which one of the first and second TCAVCS is supplied onto the control node of the auxiliary varactor circuit.

31. The method of claim 30, wherein the first and second main varactor circuit portions are parts of a main varactor circuit.

32. The method of claim 30, wherein the first and second main varactor circuit portions are parts of a main varactor circuit, the method further comprising:

controlling a digitally programmable coarse tuning capacitor bank circuit coupled in parallel with the main varactor circuit, wherein the digitally programmable coarse tuning capacitor bank circuit is a part of the VCO, wherein the digitally programmable coarse tuning capacitor bank circuit has a digitally programmable capacitance, and wherein the multi-bit digital control word at least in part determines a magnitude of the digitally programmable capacitance.

33. The method of claim 29, further comprising:

receiving the multi-bit digital control word onto the VCO, wherein the multi-bit digital control word determines how the first and second TCAVCS changes as a function of temperature.

34. The method of claim 29, wherein the first main varactor circuit portion comprises:

a first varactor having a first lead and a second lead, wherein the first lead of the first varactor is coupled to a first node;

a second varactor having a first lead and a second lead, wherein the first lead of the second varactor is coupled to a second node, and wherein the second lead of the second varactor is coupled to the second lead of the first varactor at a first control node; and

a first analog multiplexing circuit that couples a selected one of the FTAVCS and the first TCAVCS onto the first control node, and

wherein the second main varactor circuit portion comprises;

a third varactor having a first lead and a second lead, wherein the first lead of the third varactor is coupled to the first node;

a fourth varactor having a first lead and a second lead, wherein the first lead of the fourth varactor is coupled to the second node, and wherein the second lead of the fourth varactor is coupled to the second lead of the third varactor at a second control node; and

a second analog multiplexing circuit that couples a selected one of the FTAVCS and the first TCAVCS onto the second control node.

35. An apparatus comprising:

a first signal input conductor for receiving a Fine Tuning Analog Voltage Control Signal (FTAVCS) from a loop filter;

a second signal input conductor for receiving a first Temperature Compensation Analog Voltage Control Signal (TCAVCS), wherein the first TCAVCS has a voltage that varies as a function of temperature;

a third signal input conductor for receiving a second Temperature Compensation Analog Voltage Control Signal (TCAVCS), wherein the second TCAVCS has a voltage that varies as a function of temperature;

means for providing a first variable capacitance between a first node and a second node such that if a first digital control bit has a first digital value then the FTAVCS on the first signal input conductor is used to control the first variable capacitance whereas if the first digital control bit has a second digital value opposite the first digital value then the first TCAVCS on the second signal input conductor is used to control the first variable capacitance; and

means for providing a second variable capacitance between the first node and the second node such that if a second digital control bit has a third digital value then the first TCAVCS on the second signal input conductor is used to control the second variable capacitance whereas if the second digital control bit has a fourth digital value opposite the third digital value then the second TCAVCS on the third signal input conductor is used to control the second variable capacitance.

36. The apparatus of claim 35, further comprising:

means for providing a third variable capacitance between the first node and the second node such that if a third digital control bit has a first digital value then the FTAVCS on the first signal input conductor is used to control the second variable capacitance whereas if the second digital control bit has a second digital value opposite the first digital value then the TCAVCS on the second signal input conductor is used to control the second variable capacitance.

37. The apparatus of claim 36, wherein the apparatus is a Voltage Controlled Oscillator (VCO), and wherein the means for providing the first variable capacitance, the means for providing the second variable capacitance, and the means for providing the third variable capacitance are parts of a main varactor circuit of the VCO.

38. The apparatus of claim 37, further comprising:

a temperature compensation voltage generating circuit that generates the first TCAVCS such that if a digital control value received by means for generating has a first digital value then the voltage of the first TCAVCS varies as a function of temperature in a first way, whereas if the digital control value received by the means for generating has a second digital value then the voltage of the first TCAVCS varies as a function of temperature in a second way.

39. A non-transitory processor-readable medium storing a set of processor-executable instructions, wherein execution of the set of processor-executable instructions by a processor is for:

causing the processor to generate first control information for controlling a first main varactor circuit such that a selected one of a Fine Tuning Analog Voltage Control Signal (FTAVCS) and a first Temperature Compensation Analog Voltage Control Signal (TCAVCS) is supplied onto a control node of the first main varactor circuit, wherein the FTAVCS is received from a loop filter of a VCO, wherein the first TCAVCS has a voltage that varies with temperature, and wherein the first main varactor circuit is a part of the VCO; and

causing the processor to generate second control information for controlling a first auxiliary varactor circuit such that a selected one of the first TCAVCS and a second Temperature Compensation Analog Voltage Control Signal (TCAVCS) is supplied onto a control node of the first auxiliary varactor circuit, wherein the second TCAVCS has a voltage that varies with temperature, wherein the first main varactor circuit is coupled in parallel with the first auxiliary varactor circuit, and wherein the first auxiliary varactor circuit is a part of the VCO.

40. The processor-readable medium of claim 39, wherein execution of the set of processor-executable instructions is also for:

causing the processor to generate third control information for controlling a second main varactor circuit such that a selected one of the FTAVCS and the first TCAVCS is supplied onto a control node of the second main varactor circuit, and wherein the second main varactor circuit is a part of the VCO.

41. The processor-readable medium of claim 39, wherein execution of the set of processor-executable instructions is also for:

causing the processor to generate fourth control information for controlling a voltage generating circuit that generates the first TCAVCS such that the voltage of the first TCAVCS varies in a first way with temperature if the fourth control information has a first digital value whereas the voltage of the first TCAVCS varies in a second way with temperature if the fourth control information has a second digital value.

42. A method of manufacturing an integrated circuit comprising:

fabricating a fine tuning analog signal input conductor;

fabricating a first varactor and a second varactor such that a lead of the first varactor is coupled to a first control node and such that a lead of the second varactor is coupled to the first control node;

fabricating a third varactor and a fourth varactor such that a lead of the third varactor is coupled to a second control node and such that a lead of the fourth varactor is coupled to the second control node;

fabricating a first analog multiplexing circuit having an output coupled to the first control node, and having a first input coupled to the fine tuning analog signal input conductor;

fabricating a second analog multiplexing circuit having an output coupled to the second control node;

fabricating a first temperature compensation voltage generating circuit having an output coupled to a second input of the first and second analog multiplexing circuits;

fabricating a second temperature compensation voltage generating circuit having an output coupled to a first input of the second analog multiplexing circuit , wherein the fine tuning analog signal input conductor, the first varactor, the second varactor, the third varactor, the fourth varactor, the first and second analog multiplexing circuits and the first and second temperature compensation voltage generating circuits are all parts of the integrated circuit.