High dynamic range time-varying integrated receiver for elimination of off-chip filters

1. A receiver circuit comprising:

a quadrature passive mixer having an input and an output, and an input impedance of the quadrature passive mixer provides a band-pass response;

one or more output impedances coupled to the output of the quadrature passive mixer, wherein the one or more output impedances set a bandwidth of the band-pass response provided at the input of the quadrature passive mixer; and

a low noise amplifier (LNA) having an input and an output coupled to the quadrature passive mixer, the LNA configured to provide substantially linear transconductance over a predetermined input range.

2. The receiver of claim 1 , wherein the LNA is a common source amplifier.

3. The receiver of claim 1 , wherein the LNA is a differential amplifier.

4. The receiver of claim 1 wherein a frequency of operation corresponds to a channel in a wireless communications band.

5. The receiver of claim 1 wherein the receiver is selected from one or more of the group comprising a low intermediate frequency receiver and a direct conversion receiver.

6. The receiver of claim 1 wherein a frequency of operation corresponds to a channel in a GSM band.

7. The receiver of claim 1 wherein the quadrature passive mixer further comprises:

a plurality of transistors; and

wherein the plurality of transistors are driven with substantially differential signals.

8. The receiver of claim 1 wherein the quadrature passive mixer of claim 1 further comprises:

a plurality of FET switches; and

wherein two or more of the FET switches are biased to approximately the same voltage.

9. The receiver of claim 1 wherein LO inputs of one or more switches of the quadrature passive mixer are driven by buffers through series-resonant LC structures.

10. A receiver circuit comprising:

a mixer having an input, an output, and an input impedance that provides a band-pass response;

an output impedance coupled to the output of the mixer; and

a low noise amplifier (LNA) having an input and an output coupled to the mixer, the LNA configured to provide substantially linear transconductance over a predetermined input range,

wherein the output impedance sets a bandwidth of a band-pass response provided at the input of the mixer.

11. The receiver of claim 10 wherein the linear transconductance of the LNA input reduces degradation of an in-band signal in the presence of an out-of band signal.

12. The receiver of claim 10 , wherein the mixer further comprises a plurality of transistors that are driven with substantially differential signals.

13. The receiver of claim 10 wherein the mixer comprises:

a local oscillator (LO) input receiving a signal having a frequency F LO ;

a signal input receiving a signal having a frequency F SIG ;

the output impedance that is high at frequencies of |F Lo −F SIG | and |F LO +F SIG | and low at other frequencies; and

the mixer is coupled to the output impedance, the LO and the signal input, wherein an impedance presented at the signal input is high for signals at F SIG if F SIG is a predetermined signal frequency, and low at other frequencies.

14. The receiver of claim 10 , wherein the mixer comprises:

an in-phase output;

a quadrature output;

a local oscillator (LO) generating a frequency and driving the mixer near a desired input signal frequency;

two load networks, each of which presents a low pass impedance response near zero frequency and a high impedance response at twice the LO frequency, wherein each of the in-phase output and the quadrature phase outputs are connected to one of the load networks; and

wherein each of the load networks interacts with time varying properties of the mixer to provide a band-pass response at the input.

15. The receiver of claim 10 , wherein the mixer comprises:

an in-phase differential output;

a quadrature differential output;

a local oscillator (LO) generating a frequency and driving the mixer near a desired input signal frequency;

each of the differential outputs is connected to a load network which presents a low pass impedance response near zero frequency and a high impedance response at twice the LO frequency; and

each of the load networks interacts with time varying properties of the mixer to provide a band-pass response at the input.

16. The receiver of claim 10 wherein the mixer is driven at a local oscillator (LO) frequency, and comprises:

a first unfiltered output;

a second unfiltered output;

a first filtered output;

a second filtered output;

the first unfiltered output is connected to the first filtered output through a first parallel resonant LC tank;

the second unfiltered output is connected to the second filtered output through a second parallel resonant LC tank;

the first filtered output is connected to the second filtered output through a capacitor;

the first parallel resonant LC tank and the second parallel resonant LC tank are each tuned to provide high impedance at twice the LO frequency; and

the first parallel resonant LC tank, the second parallel resonant LC tank, and the capacitor interact to provide a band-pass input impedance at the input.

17. A receiver circuit comprising:

means for providing a band-pass response of an input impedance of a passive mixer;

means for providing an output impedance coupled to the passive mixer sets a bandwidth of the band-pass response of the input impedance; and

a low noise amplifier (LNA) having an input and an output coupled to the passive mixer, the LNA configured to provide substantially linear transconductance over a predetermined input range.

18. The receiver of claim 17 wherein the LNA and the passive mixer are configured so that a band-pass mixer input impedance response is presented to the output of the LNA so as to substantially reduce a LNA voltage gain for unwanted signals presented to the LNA input.

19. The receiver of claim 17 wherein a frequency of operation corresponds to a channel in a wireless voice communications band.

20. The receiver of claim 17 wherein the substantially linear transconductance of the LNA input reduces degradation of an in-band signal in the presence of an out-of band signal.

21. A receiver circuit comprising:

a mixer having an input and an output, the mixer comprising a first parallel resonant LC tank, a second parallel resonant LC tank, and a capacitor at the output to provide an input impedance that provides a band-pass response; and

a low noise amplifier (LNA) having an input and an output coupled to the mixer, the LNA configured to provide substantially linear transconductance over a predetermined input range.

22. The receiver of claim 21 wherein the mixer is driven at a local oscillator (LO) frequency, and comprises:

a first unfiltered output;

a second unfiltered output;

a first filtered output;

a second filtered output;

wherein the first unfiltered output is connected to the first filtered output through the first parallel resonant LC tank;

wherein the second unfiltered output is connected to the second filtered output through the second parallel resonant LC tank;

wherein the first filtered output is connected to the second filtered output through the capacitor;

wherein the first parallel resonant LC tank and the second parallel resonant LC tank are each tuned to provide high impedance at twice the LO frequency; and

wherein the first parallel resonant LC tank, the second parallel resonant LC tank, and the capacitor interact to provide a band-pass input impedance at the input.