Mixer Circuit and Method

Abstract

A method of providing an input signal to a mixer circuit comprises coupling an output signal from a low-noise amplifier circuit to a mixer input of the mixer circuit via an AC coupling circuit, comprising an inductive of capacitive coupling circuit. For capacitive coupling configurations, a coupling capacitor is configured to have a capacitance value determined as a function of a transconductance sensitivity of the mixer circuit. For balanced output configurations of the low-noise amplifier circuit, matched coupling capacitors are used for coupling the balanced output signals to respective inputs of the mixer circuit. In one embodiment, the mixer circuit comprises a quadrature mixer circuit, which may be in a balanced or double-balanced configuration. In another embodiment, the mixer circuit comprises a four-phase mixer circuit, which may be configured as a balanced four-phase mixer circuit coupled to the low-noise amplifier circuit via inductive or capacitive embodiments of the coupling circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of a receiver circuit.

FIG. 2 is a block diagram of one embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 3 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 4 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 5 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 6 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 7 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 8 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 9 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 10 is a block diagram of another embodiment of amplifier, mixer, and coupling circuits for use in a wireless communication receiver.

FIG. 11 is a block diagram of one embodiment of a wireless communication apparatus, including an embodiment of the amplifier, mixer, and coupling circuits as taught herein.

Claims

1. A receiver circuit comprising: a low-noise amplifier circuit;a quadrature mixer circuit; anda capacitive coupling circuit comprising matched capacitive coupling circuits to couple an output signal of the low-noise amplifier circuit into quadrature inputs of the quadrature mixer circuit.

2. The receiver circuit of claim 1, wherein the low-noise amplifier circuit comprises a single-ended low-noise amplifier circuit providing a single output signal, and wherein the capacitive coupling circuit splits the single-ended output signal into the quadrature inputs of the quadrature mixer circuit.

3. The receiver circuit of claim 1, wherein the matched coupling circuits each include a coupling capacitor sized relative to a transconductance sensitivity of the receiver circuit.

4. The receiver circuit of claim 3, wherein the coupling capacitor in each matched coupling circuit is sized such that ωC>gm, where ω is a frequency of interest, C is a capacitance value of the coupling capacitor, and gm is a transconductance value of the quadrature mixer circuit.

5. The receiver circuit of claim 1, wherein the low-noise amplifier circuit includes a balanced output, and wherein the capacitive coupling circuit capacitively couples balanced output signals from the low-noise amplifier circuit to quadrature inputs of the quadrature mixer circuit.

6. The receiver circuit of claim 5, wherein the capacitive coupling circuit includes matched coupling capacitors for capacitively coupling the balanced output signals to the quadrature inputs of the quadrature mixer circuit.

7. The receiver circuit of claim 1, wherein the quadrature mixer circuit comprises a double-balanced quadrature mixer circuit, and wherein the low-noise amplifier circuit includes a balanced output providing first and second output signals to first and second balanced quadrature inputs of the quadrature mixer circuit, respectively.

8. The receiver circuit of claim 7, wherein the quadrature mixer circuit includes a capacitive coupling circuit for each of the first and second balanced quadrature inputs, and wherein each capacitive coupling circuit includes matched coupling capacitors.

9. The receiver circuit of claim 8, wherein each of the first and second balanced quadrature inputs includes a single-ended termination circuit.

10. A wireless communication apparatus including the receiver circuit of claim 1.

11. A receiver circuit comprising: a low-noise amplifier circuit;a four-phase mixer circuit; anda capacitive coupling circuit to couple an output signal of the low-noise amplifier circuit into a mixer input of the four-phase mixer circuit.

12. The receiver circuit of claim 11, wherein the low-noise amplifier circuit comprises a single-ended low-noise amplifier circuit providing a single output signal, and wherein the capacitive coupling circuit couples the single output signal into a single-ended mixer input of the four-phase mixer circuit.

13. The receiver circuit of claim 11, wherein the capacitive coupling circuit includes a coupling capacitor sized relative to a transconductance sensitivity of the four-phase mixer circuit.

14. The receiver circuit of claim 13, wherein the coupling capacitor is sized such that ωC>gm, where ω is a frequency of interest, C is a capacitance value of the coupling capacitor, and gm is a transconductance value of the four-phase mixer circuit.

15. The receiver circuit of claim 11, wherein the four-phase mixer circuit comprises a double-balanced four-phase mixer circuit, the low-noise amplifier circuit includes a balanced output, and the capacitive coupling circuit includes matched coupling capacitors capacitively coupling balanced output signals from the low-noise amplifier circuit to respective balanced mixer inputs of the double-balanced four-phase mixer circuit.

16. The receiver circuit of claim 15, wherein the balanced mixer inputs of the double-balanced four-phase mixer circuit comprise singled-ended termination circuits.

17. A wireless communication apparatus including the receiver circuit of claim 11.

18. A method of providing an input signal to a mixer circuit comprising: coupling an output signal from a low-noise amplifier circuit to a mixer input of the mixer circuit via a coupling capacitor; andconfiguring the coupling capacitor to have a capacitance value determined as a function of a transconductance sensitivity of the mixer circuit.

19. The method of claim 18, wherein the low-noise amplifier circuit provides balanced output signals, and wherein coupling an output signal from a low-noise amplifier circuit to a mixer input of the mixer circuit via a coupling capacitor comprises coupling the balanced output signals to respective mixer inputs via matched coupling capacitors.

20. A receiver circuit comprising: a low-noise amplifier circuit;a quadrature mixer circuit; andan inductive coupling circuit comprising one or more transformer-coupled inductors configured to couple an output signal of the low-noise amplifier circuit into quadrature inputs of the quadrature mixer circuit.

21. The receiver circuit of claim 20, wherein the low-noise amplifier circuit comprises a single-ended low-noise amplifier circuit providing a single output signal, and wherein the one or more transformer coupled inductors of the inductive coupling circuit comprise a transformer-coupled inductor providing a balanced RF input signal to the quadrature mixer circuit.

22. The receiver circuit of claim 21, wherein the quadrature mixer circuit comprises a quadrature mixer circuit configured for four-phase local oscillator drive signals.

23. The receiver circuit of claim 20, wherein the low-noise amplifier circuit comprises a single-ended low-noise amplifier circuit providing a single output signal, and wherein the one or more transformer coupled inductors of the inductive coupling circuit split the single output signal into a pair of balanced RF input signals and comprise a pair of matched transformer-coupled inductors.

24. A wireless communication apparatus including the receiver circuit of claim 20.

25. A method of providing a mixer input signal to a mixer circuit comprising: obtaining an amplifier output signal from a low-noise amplifier circuit configured to receive a corresponding amplifier input signal; andinductively coupling the amplifier output signal from the low-noise amplifier circuit to quadrature inputs of a quadrature mixer circuit via one or more transformer-coupled inductors.

26. The method of claim 25, wherein the low-noise amplifier circuit is configured to provide the amplifier output signal as a single-ended amplifier output signal, and wherein inductively coupling the amplifier output signal from the low-noise amplifier circuit to quadrature inputs of a quadrature mixer circuit via one or more transformer-coupled inductors comprises configuring the one or more transformer-coupled inductors to convert the single-ended amplifier output signal into a balanced mixer input signal for applying to the quadrature inputs of the mixer circuit.

27. The method of claim 26, further comprising configuring the quadrature mixer circuit for operation with four-phase local oscillator drive signals.

28. The method of claim 25, wherein the low-noise amplifier circuit comprises a single-ended low-noise amplifier circuit providing a single amplifier output signal, and wherein inductively coupling the amplifier output signal from the low-noise amplifier circuit to quadrature inputs of a quadrature mixer circuit via one or more transformer-coupled inductors comprises configuring the one or more transformer-coupled inductors as a pair of matched transformer-coupled inductors that split the single amplifier output signal into a pair of balanced quadrature mixer input signals.