Half duplex RF transceiver

• US 5,511,236 A
• Filed: 08/17/1994
• Issued: 04/23/1996
• Est. Priority Date: 12/07/1993
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Umstattd, Ruth, Madsen, Benny
• Primary Examiner(s): Faile, Andrew I.
• Application Number:
  US08/291,876
• Time in Patent Office: 615 Days
• Field of Search: 455/76, 455/78, 455/84, 455/85, 455/86, 455/119, 455/126, 455/314, 455/315, 455/316, 455/329, 455/324, 455/337, 329/323, 329/325, 331/12, 331/2, 332/103, 332/127, 332/128, 375/7, 375/80, 375/81
• US Class Current: 455/76
• CPC Class Codes: H03C 2200/0058 Quadrature arrangements
• CPC Class Codes: H03C 3/0975 applying frequency modulation in the phase locked loop at components other than the divider, the voltage controlled oscillator or the reference clock
• CPC Class Codes: H03C 3/0983 containing in the loop a mixer other than for phase detection

Abstract

A radio frequency (RF) transceiver for modulating and demodulating RF signals with a direct modulation transmitter and a dual intermediate frequency (IF) receiver, respectively, includes a local oscillator, three frequency converters, a demodulator, a carrier generator, a modulator, a controller and two signal switches. The local oscillator (e.g. phase lock loop PLL!) provides a first local oscillator (LO) signal. One frequency converter (e.g. mixer) frequency converts an incoming modulated RF signal with the first LO signal to provide a first modulated IF signal. A second frequency converter frequency converts the first modulated IF signal with a second LO signal to provide a second modulated IF signal. The demodulator also receives the second LO signal and demodulates therewith the second modulated IF signal. The carrier generator (e.g. voltage-controlled oscillator VCO!) receives a transmitter control signal and in accordance therewith generates a transmitter carrier signal. The third frequency converter receives the transmitter carrier signal and the first LO signal and in response thereto provides the second LO signal. The modulator selectively receives and modulates the second LO signal to provide a third modulated IF signal. The controller (e.g. phase detector) receives a reference signal and selectively receives the second LO signal and the third modulated IF signal and in response thereto provides the transmitter control signal. The signal switches receive a mode control signal and in response to one state thereof connect the controller to the third frequency converter and in response to another state thereof connect the modulator to both the third frequency converter and controller.

Claims

1. A radio frequency (RF) transceiver for modulating and demodulating RF signals, said transceiver comprising:

a first local oscillator for providing a first local oscillator (LO) signal;

a dual conversion receiver, coupled to said first local oscillator, for receiving said first LO signal and a second LO signal and in accordance therewith frequency converting and demodulating an incoming modulated RF signal, wherein said frequency converting is done with said first and second LO signals and said demodulating is done with said second LO signal; and

a transmitter, coupled to said first local oscillator and said dual conversion receiver and including a second local oscillator, for receiving said first LO signal, a reference signal and a mode control signal and in accordance therewith generating and providing said second LO signal, and further for receiving said first LO signal, said reference signal, said mode control signal and at least one modulation signal and in accordance therewith generating and modulating said second LO signal for providing an outgoing modulated RF signal.

2. A transceiver as recited in claim 1, wherein said first local oscillator comprises a phase lock loop (PLL).

3. A transceiver as recited in claim 1, wherein said dual conversion receiver comprises:

a dual frequency converter for frequency converting said incoming modulated RF signal with said first LO signal to produce a first modulated intermediate frequency (IF) signal and for frequency converting said first modulated IF signal with said second LO signal to produce a second modulated IF signal; and

a demodulator, coupled to said dual frequency converter, for receiving said second LO signal and in accordance therewith demodulating said second modulated IF signal.

4. A transceiver as recited in claim 3, wherein said dual frequency converter comprises a plurality of serially coupled mixers.

5. A transceiver as recited in claim 3, wherein said demodulator comprises a quadrature demodulator.

6. A transceiver as recited in claim 5, wherein said demodulator further comprises a frequency divider, coupled to said quadrature demodulator, for frequency dividing said second LO signal for use by said quadrature demodulator.

7. A transceiver as recited in claim 1, wherein said transmitter comprises a feedback-modulated PLL.

8. A transceiver as recited in claim 1, wherein said transmitter comprises a modulated frequency synthesizer.

9. A transceiver as recited in claim 1, wherein said carrier generator comprises a voltage-controlled oscillator (VCO).

10. A transceiver as recited in claim 1, wherein said frequency converter comprises a mixer.

11. A transceiver as recited in claim 1, wherein said modulator comprises a quadrature modulator.

12. A transceiver as recited in claim 1, wherein said controller comprises a phase detector.

13. A transceiver as recited in claim 1, wherein said switchable coupler comprises a plurality of signal switches.

14. A radio frequency (RF) transceiver for modulating and demodulating RF signals with a direct modulation transmitter and a dual intermediate frequency (IF) receiver, respectively, said transceiver comprising:

a local oscillator for providing a first local oscillator (LO) signal;

a first frequency converter, coupled to said local oscillator, for receiving said first LO signal and for receiving and frequency converting therewith an incoming modulated RF signal to provide a first modulated IF signal;

a second frequency converter, coupled to said first frequency converter, for receiving a second LO signal and for receiving and frequency converting therewith said first modulated IF signal to provide a second modulated IF signal;

a demodulator, coupled to said second frequency converter, for receiving said second LO signal and for receiving and demodulating therewith said second modulated IF signal;

a carrier generator for receiving a transmitter control signal and in accordance therewith generating a transmitter carrier signal;

a third frequency converter, coupled to said carrier generator and said local oscillator, for receiving said transmitter carrier signal and said first LO signal and in response thereto providing said second LO signal;

a modulator for selectively receiving and modulating said second LO signal to provide a third modulated IF signal;

a controller, coupled to said carrier generator, for receiving a reference signal and selectively receiving said second LO signal and said third modulated IF signal and in response thereto providing said transmitter control signal; and

a switchable coupler for receiving a mode control signal and in response thereto coupling said controller to said third frequency converter and coupling said modulator to said third frequency converter and to said controller.

15. A transceiver as recited in claim 14, wherein said carrier generator, said third frequency converter, said modulator and said controller together form a feedback-modulated phase lock loop (PLL).

16. A transceiver as recited in claim 14, wherein said carrier generator, said third frequency converter, said modulator and said controller together form a modulated frequency synthesizer.

17. A transceiver as recited in claim 14, wherein said local oscillator comprises a PLL.

18. A transceiver as recited in claim 14, wherein said first frequency converter comprises a mixer.

19. A transceiver as recited in claim 14, wherein said second frequency converter comprises a mixer.

20. A transceiver as recited in claim 14, wherein said demodulator comprises a quadrature demodulator.

21. A transceiver as recited in claim 20, wherein said demodulator further comprises a frequency divider, coupled to said quadrature demodulator, for frequency dividing said second LO signal for use by said quadrature demodulator.

22. A transceiver as recited in claim 14, wherein said carrier generator comprises a voltage-controlled oscillator (VCO).

23. A transceiver as recited in claim 14, wherein said third frequency converter comprises a mixer.

24. A transceiver as recited in claim 14, wherein said modulator comprises a quadrature modulator.

25. A transceiver as recited in claim 14, wherein said controller comprises a phase detector.

26. A transceiver as recited in claim 14, wherein said switchable coupler comprises a plurality of signal switches.

27. A method for modulating and demodulating RF signals by direct transmission modulation and dual intermediate frequency (IF) reception, respectively, said method comprising the steps of:

providing a first local oscillator (LO) signal;

receiving an incoming modulated RF signal;

frequency converting said incoming modulated RF signal with said first LO signal to provide a first modulated IF signal;

receiving a transmitter control signal and in accordance therewith generating a transmitter carrier signal;

receiving said transmitter carrier signal and said first LO signal and in response thereto providing a second LO signal;

frequency converting said first modulated IF signal with said second LO signal to provide a second modulated IF signal;

demodulating said second modulated IF signal with said second LO signal;

receiving a reference signal;

receiving a mode control signal which includes a plurality of signal states;

in response to a first one of said plurality of mode control signal states, providing said transmitter control signal in accordance with said reference signal and said second LO signal; and

in response to a second one of said plurality of mode control signal states;

modulating said second LO signal to provide a third modulated IF signal; and

providing said transmitter control signal in accordance with said reference signal and said third modulated IF signal, whereby said transmitter carrier signal forms an outgoing modulated RF signal.

28. A method as recited in claim 27, wherein said step of receiving a transmitter control signal and in accordance therewith generating a transmitter carrier signal comprises receiving a phase lock loop (PLL) oscillator control signal.

29. A method as recited in claim 27, wherein said step of receiving said transmitter carrier signal and said first LO signal and in response thereto providing said second LO signal comprises mixing said transmitter carrier signal and said first LO signal.

30. A method as recited in claim 27, wherein said step of demodulating said second modulated IF signal with said second LO signal comprises quadrature demodulating said second modulated IF signal.

31. A method as recited in claim 30, wherein said step of demodulating said second modulated IF signal with said second LO signal further comprises frequency dividing said second LO signal for use in said quadrature demodulating of said second modulated IF signal.

32. A method as recited in claim 27, wherein said step of providing said transmitter control signal in accordance with said reference signal and said second LO signal comprises phase locking said transmitter carrier signal to said reference signal.

33. A method as recited in claim 27, wherein said step of modulating said second LO signal to provide said third modulated IF signal comprises quadrature modulating said second LO signal.

34. A method as recited in claim 27, wherein said step of providing said transmitter control signal in accordance with said reference signal and said third modulated IF signal comprises phase locking said transmitter carrier signal to said reference signal.

35. A method for modulating and demodulating RF signals by direct transmission modulation and dual intermediate frequency (IF) reception, respectively, said method comprising the steps of:

receiving a reference signal;

receiving a mode control signal which includes a plurality of signal states;

providing a first local oscillator (LO) signal;

in response to a first one of said plurality of mode control signal states;

receiving an incoming modulated RF signal;

frequency converting said incoming modulated RF signal with said first LO signal to provide a first modulated IF signal;

receiving a transmitter control signal and in accordance therewith generating a transmitter carrier signal;

receiving said transmitter carrier signal and said first LO signal and in response thereto providing a second LO signal;

frequency converting said first modulated IF signal with said second LO signal to provide a second modulated IF signal;

demodulating said second modulated IF signal with said second LO signal;

providing said transmitter control signal in accordance with said reference signal and said second LO signal; and

in response to a second one of said plurality of mode control signal states;

receiving said transmitter control signal and in accordance therewith generating said transmitter carrier signal;

receiving said transmitter carrier signal and said first LO signal and in response thereto providing said second LO signal;

modulating said second LO signal to provide a third modulated IF signal; and

providing said transmitter control signal in accordance with said reference signal and said third modulated IF signal, whereby said transmitter carrier signal forms an outgoing modulated RF signal.

36. A method as recited in claim 35, wherein said steps of receiving said transmitter control signal and in accordance therewith generating said transmitter carrier signal each comprises receiving a phase lock loop (PLL) oscillator control signal.

37. A method as recited in claim 35, wherein said steps of receiving said transmitter carrier signal and said first LO signal and in response thereto providing said second LO signal each comprises mixing said transmitter carrier signal and said first LO signal.

38. A method as recited in claim 35, wherein said step of demodulating said second modulated IF signal with said second LO signal comprises quadrature demodulating said second modulated IF signal.

39. A method as recited in claim 38, wherein said step of demodulating said second modulated IF signal with said second LO signal further comprises frequency dividing said second LO signal for use in said quadrature demodulating of said second modulated IF signal.

40. A method as recited in claim 35, wherein said step of providing said transmitter control signal in accordance with said reference signal and said second LO signal comprises phase locking said transmitter carrier signal to said reference signal.

41. A method as recited in claim 35, wherein said step of modulating said second LO signal to provide said third modulated IF signal comprises quadrature modulating said second LO signal.

42. A method as recited in claim 35, wherein said step of providing said transmitter control signal in accordance with said reference signal and said third modulated IF signal comprises phase locking said transmitter carrier signal to said reference signal.

43. A radio frequency (RF) transceiver for modulating and demodulating RF signals, said transceiver comprising:

a local oscillator for providing a first local oscillator (LO) signal;

a dual conversion receiver, coupled to said local oscillator, for receiving said first LO signal and a second LO signal and in accordance therewith frequency convening and demodulating an incoming modulated RF signal; and

a transmitter, coupled to said local oscillator and said dual conversion receiver, for receiving said first LO signal, a reference signal and a mode control signal and in accordance therewith providing said second LO signal, and further for receiving said first LO signal, said reference signal, said mode control signal and at least one modulation signal and in accordance therewith providing an outgoing modulated RF signal, wherein said modulated transmitter comprises;

a carrier generator for receiving a transmitter control signal and in accordance therewith generating a transmitter carrier signal;

a frequency converter, coupled to said carrier generator, for receiving said transmitter carrier signal and said first LO signal and in response thereto providing said second LO signal;

a modulator for selectively receiving and modulating said second LO signal to provide a third modulated IF signal;

a controller, coupled to said carrier generator, for receiving said reference signal and selectively receiving said second LO signal and said third modulated IF signal and in response thereto providing said transmitter control signal; and

a switchable coupler for receiving said mode control signal and in response thereto coupling said controller to said frequency converter and coupling said modulator to said frequency converter and to said controller.