Quadrature generator with image reject mixer

• US 7,130,599 B2
• Filed: 03/02/2001
• Issued: 10/31/2006
• Est. Priority Date: 11/03/2000
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Persico, Charles J., Jaffee, James, Ciccarelli, Steven C.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Chow, Charles
• Application Number:
  US09/798,378
• Publication Number:
  US 20020055337A1
• Time in Patent Office: 2,069 Days
• Field of Search: 455/112, 455/47, 455/109, 455/203, 455/333, 455/327, 455/118, 455/306, 455/307, 455/550.1, 455/575.1, 455/146, 455/190, 455/173.1, 455/182.1, 455/186.1, 455/515, 455/67.11, 455/67.13, 455/113, 455/191.1, 455/209, 455/207, 455/256, 455/264, 455255-263, 455313-318, 455/315, 455/323, 455/302, 455/304, 455/285, 455/326, 455/183.1, 455/208, 375/295, 375/279, 375/329, 375/330, 375/332, 375/308, 375 52- 54, 375/67, 375/83, 375/335, 375/344, 375/327, 375/324, 375/349, 329/305, 329/306, 332/103, 332/104, 332/105, 332/170, 331/135, 331/2, 331/1.R, 331/22, 331/34, 331/46, 331/12, 331/18, 331/54, 342/194, 327/255, 327/552, 327/73, 327/68, 327/254
• US Class Current: 455/147
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H03D 7/166 using two or more quadrature frequency translation stages

Abstract

In an exemplary application, an apparatus according to a disclosed embodiment receives a radio frequency signal and outputs an intermediate frequency signal. Rejection of image components in the intermediate frequency signal is obtained without the need to preprocess the radio frequency signal with an image reject filter. Such an apparatus may also exhibit an image rejection performance that is robust to frequency deviation of a local oscillator.

Claims

1. A convener for use in RF-to-IF downconversion comprising:

an image reject mixer configured and arranged to receive an input signal and a quadrature signal pair and to produce an output signal having a non-zero center frequency and based on the input signal and the quadrature signal pair; and

a quadrature signal generator configured and arranged to receive a first oscillator signal and a second oscillator signal and to produce the quadrature signal pair,

wherein each of the quadrature signal pair is based on both the first oscillator signal and the second oscillator signal.

2. The convener according to claim 1, wherein the image reject mixer comprises:

a first mixer configured and arranged to receive one among the quadrature signal pair and a signal based on the input signal and to output a first mixed signal; and

a second mixer configured and arranged to receive the other among the quadrature signal pair and a signal based on the input signal and to output a second mixed signal,

wherein the output signal is based on the first and second mixed signals.

3. The converter according to claim 2, wherein the image reject mixer further comprises a phase shifter configured and arranged to receive one among the first and second mixed signals and to output a phase-shifted signal, wherein the output signal is based on the phase-shifted signal.

4. The converter according to claim 3, wherein the phase shifter comprises a polyphase filter.

5. The convener according to claim 3, wherein the phase shifter is configured and arranged to perform a phase shift having a magnitude of ninety degrees.

6. The convener according to claim 2, wherein the image reject mixer further comprises:

a first phase shifter configured and arranged to receive the first mixed signal and to output a first phase-shifted signal; and

a second phase shifter configured and arranged to receive the second mixed signal and to output a second phase-shifted signal,

wherein the output signal is based on the first and second phase-shifted signals.

7. The convener according to claim 6, wherein the magnitude of a phase difference between the first and second phase-shifted signals is ninety degrees.

8. The converter according to claim 7, wherein at least one among the first and second phase shifters comprises a polyphase filter.

9. The convener according to claim 6, wherein at least one among the first and second phase shifters comprises a polyphase filter.

10. The converter according to claim 2, wherein the image reject mixer further comprises a combiner configured and arranged to receive a signal at least based on the first mixed signal and a signal at least based on the second mixed signal and to output the output signal.

11. The convener according to claim 2, wherein at least one among said first mixer and said second mixer comprises a Gilbert cell multiplier.

12. The convener according to claim 1, wherein the quadrature signal generator is robust to changes in the frequency of at least one among the first and second oscillator signals.

13. The convener according to claim 1, wherein a frequency of at least one among the quadrature signal pair is one among a sum and a difference of a frequency of the first oscillator signal and a frequency of the second oscillator signal.

14. The convener according to claim 13, wherein a frequency of one among the quadrature signal pair is equal to a frequency of the other among the quadrature signal pair.

15. The convener according to claim 1, wherein a frequency of the input signal is greater than four hundred megahertz.

16. In a converter for use in a RF-to-IF downconversion, a method comprising:

receiving a first oscillator signal and a second oscillator signal;

producing a quadrature signal pair based on the first oscillator signal and the second oscillator signal;

receiving an input signal; and

producing an output signal having a non-zero center frequency and based on the input signal and the quadrature signal pair,

wherein each of the quadrature signal pair is based on both the first oscillator signal and the second oscillator signal.

17. The method of claim 16, wherein a frequency of one among the quadrature signal pair is equal to a frequency of the other among the quadrature signal pair.

18. The method of claim 17, wherein the frequency of the quadrature signal pair is one among the sum and the difference of the frequencies of the first and second oscillator signals.

19. The method of claim 16, wherein producing a quadrature signal pair includes producing a quadrature signal pair whose phase difference is robust to changes in at least one among the first and second oscillator signals.

20. The method of claim 16, wherein producing an output signal includes producing a shifted input signal pair having the same frequency as the input signal, wherein a phase difference between the shifted input signal pair is ninety degrees.

21. The method of claim 16, wherein producing an output signal includes:

mixing the input signal with one among the quadrature signal pair to obtain a first mixed signal; and

mixing the input signal with the other among the quadrature signal pair to obtain a second mixed signal.

22. The method of claim 21, wherein producing an output signal further includes performing a phase shift on at least one among the first and second mixed signals.

23. The method of claim 22, wherein performing a phase shift includes performing a phase shift having a magnitude of at least forty-five degrees.

24. The method of claim 21, wherein producing an output signal further includes:

performing a phase shift on the first mixed signal to obtain a first phase-shifted signal; and

performing a phase shift on the second mixed signal to obtain a second phase-shifted signal.

25. The method of claim 24, wherein the magnitude of a phase difference between the first phase-shifted signal and the second phase-shifted signal is ninety degrees.

26. The method of claim 24, wherein producing an output signal further includes combining the first phase-shifted signal and the second phase-shifted signal.

27. An integrated circuit for use in RE-to-If downconversion comprising;

an image reject mixer configured and arranged to receive an input signal and a quadrature signal pair and to produce an output signal having a non-zero center frequency based on the input signal and the quadrature signal pair; and

a quadrature signal generator configured and arranged to receive a first oscillator signal and a second oscillator signal and to produce the quadrature signal pair,

wherein each of the quadrature signal pair is based on both the first oscillator signal and the second oscillator signal.

28. The integrated circuit according to claim 27, wherein the image reject mixer comprises:

a first mixer configured and arranged to receive one among the quadrature signal pair and a signal based on the input signal and to output a first mixed signal; and

a second mixer configured and arranged to receive the other among the quadrature signal pair and a signal based on the input signal and to output a second mixed signal,

wherein the output signal is based on the first and second mixed signals.

29. A convener for use in RF-to_IF downconversion comprising:

a generator configured and arranged to receive a first oscillator signal and a second oscillator signal and to output a quadrature signal pair having a frequency ω

g; and

an image reject mixer configured and arranged to receive the quadrature signal pair and an input signal including an information signal modulated onto a carrier having a bandwidth centered at a frequency ω

c and to output an output signal,

wherein each of the quadrature signal pair is based on both of the first oscillator signal and the second oscillator signal, and

wherein at least one among a sum and a difference of the frequencies of the first oscillator signal and the second oscillator signal is ω

g, and

wherein the output signal includes the information signal modulated onto a carrier having a bandwidth centered at one among the frequencies (ω

c−

ω

g) and (ω

c +ω

g), and

wherein the image reject mixer is further configured and arranged to suppress a component in the input signal having the frequency (2ω

g−

ω

c).

30. The convener according to claim 29, wherein the image reject mixer includes a mixer/phase shifter section, and wherein the mixer/phase shifter section receives the input signal and one of the quadrature signal pair and produces an output component signal, and wherein the output signal is based on the output component signal.