RADIO FREQUENCY RECEIVER ARCHITECTURE
A radio frequency receiver includes a passive mixer configured to receive and RF signal and a low input impedance circuit configured to receive the output of the passive mixer.
1 . A method of operating a mixer subsystem comprising:
receiving a radio frequency (RF) signal at an input of a passive mixer;
mixing the received RF signal with an output signal of a local oscillator using the passive mixer to generate a downconverted signal; and
receiving the downconverted signal at an input of a transimpedance amplifier that includes one or more feedback impedances coupled between the input of the transimpedance amplifier and an output of the transimpedance amplifier, wherein the input of the transimpedance amplifier includes one or more bipolar transistors as input devices.
2 . The method of claim 1 wherein receiving the RF signal at the input of the passive mixer includes receiving the RF input signal at the input of the passive mixer from an output of a low noise amplifier (LNA) via one or more capacitors configured to filter out a direct current (DC) component in the RF signal.
3 . The method of claim 2 wherein the LNA comprises an inductor-capacitor (LC) tank circuit or a resistor-capacitor network.
4 . The method of claim 2 wherein the LNA is single-ended or differential.
5 . The method of claim 1 wherein the passive mixer includes one or more current-mode switches.
6 . The method of claim 1 wherein the passive mixer includes one or more transistors.
7 . The method of claim 1 wherein mixing the received RF signal with the output signal of a local oscillator using the passive mixer to generate a downconverted signal includes downconverting the RF input signal to an intermediate frequency or a baseband frequency.
8 . The method of claim 1 wherein the transimpedance amplifier is configured to amplify the downconverted signal with a gain.
9 . The method of claim 1 wherein the one or more feedback impedances are configured to filter leaked transmit signals or blocking signals.
10 . The method of claim 1 wherein the transimpedance amplifier is configured to have an input impedance value on the order of ohms.
11 . The method of claim 1 wherein the transimpedance amplifier includes a source-follower amplifier.
12 . The method of claim 1 wherein the passive mixer and the transimpedance amplifier are configured for a Wideband Code Division Multiple Access (WCDMA) communication system.
13 . The method of claim 1 wherein the passive mixer or the transimpedance amplifier is includes metal-oxide-semiconductor-field-effect-transistors (MOSFET) and the one or more bipolar transistors are parasitic bipolar transistors.
14 . The method of claim 1 wherein the passive mixer or the transimpedance amplifier is formed using bipolar-CMOS (BiCMOS) or Silicon-Germanium (SiGe) process technology.
15 . A circuit comprising:
a passive mixer configured to receive a radio frequency (RF) input signal, receive a local oscillator signal, and mix the RF input signal with the local oscillator signal to generate a downconverted signal; and
a transimpedance amplifier including an input configured to receive the downconverted signal and one or more feedback impedances coupled between the input of the transimpedance amplifier and an output of the transimpedance amplifier, wherein the input of the transimpedance amplifier includes one or more bipolar transistors as input devices.
16 . The circuit of claim 15 further comprising:
a low noise amplifier (LNA) configured to output the RF signal to the passive mixer via one or more capacitors configured to filter out a direct current (DC) component in the RF signal.
17 . The circuit of claim 16 wherein the LNA comprises an inductor-capacitor (LC) tank circuit or a resistor-capacitor network.
18 . The circuit of claim 16 wherein the LNA is single-ended or differential.
19 . The circuit of claim 15 wherein the passive mixer includes one or more current-mode switches.
20 . The circuit of claim 15 wherein the passive mixer includes one or more transistors.
21 . The circuit of claim 15 wherein, to generate a downconverted signal, the passive mixer is configured to downconvert die RF signal to an intermediate frequency or a baseband frequency.
22 . The circuit of claim 15 wherein the transimpedance amplifier is configured to is configured to amplify the downconverted signal with a gain.
23 . The circuit of claim 15 wherein the one or more feedback impedances are configured to filter leaked transmit signals or blocking signals.
24 . The circuit of claim 15 wherein the amplifier is configured to have an input impedance value on the order of ohms.
25 . The circuit of claim 15 wherein the transimpedance amplifier includes a source-follower amplifier.
26 . The circuit of claim 15 wherein the passive mixer and the transimpedance amplifier are configured for a Wideband Code Division Multiple Access (WCDMA) communication system.
27 . The circuit of claim 15 wherein the passive mixer or the transimpedance amplifier is formed from metal-oxide-semiconductor-field-effect-transistors (MOSFET) and the one or more bipolar transistors of the transimpedance amplifier are parasitic bipolar transistors.
28 . The circuit of claim 15 wherein the passive mixer or the transimpedance amplifier is formed from bipolar-CMOS (BiCMOS) or Silicon-Germanium (SiGe) process technology.
29 . A full-duplex transceiver comprising:
a transmit path configured to provide a transmit signal to a duplexer;
a low noise amplifier configured to input a received signal from the duplexer and output a first amplified signal;
a passive current-mode down-converting mixer configured to input the first amplified signal and output a down-converted signal;
a transimpedance amplifier configured to input the down-converted signal and output a second amplified signal; and
a low pass filter configured to input the second amplified signal and output a filter signal.
30 . The transceiver of claim 29 wherein the transimpedance amplifier comprises bipolar transistors as input devices.
31 . The transceiver of claim 29 wherein the low noise amplifier comprises an inductor-capacitor (LC) tank circuit or a resistor-capacitor network.
32 . The transceiver of claim 29 wherein the low noise amplifier is single-ended or differential.
33 . The transceiver of claim 29 wherein the passive mixer includes one or more current-mode switches.
34 . The transceiver of claim 29 wherein the passive mixer includes one or more transistors.
35 . The transceiver of claim 29 wherein, to generate a down-converted signal, the passive mixer is configured to down-convert the RF signal to an intermediate frequency or a baseband frequency.
36 . The transceiver of claim 29 wherein the transimpedance amplifier is configured to amplify the down-converted signal with a gain.
37 . The transceiver of claim 29 wherein the transimpedance amplifier includes one or more feedback impedances configured to filter leaked transmit signals or blocking signals.
38 . The transceiver of claim 29 wherein the transimpedance amplifier is configured to have an input impedance value on the order of ohms.
39 . The transceiver of claim 29 wherein the transimpedance amplifier includes a source-follower amplifier.
40 . The transceiver of claim 29 wherein the passive mixer and the transimpedance amplifier are configured for a Wideband Code Division Multiple Access (WCDMA) communication system.
41 . The transceiver of claim 29 wherein the passive mixer or the transimpedance amplifier is formed from metal-oxide-semiconductor-field-effect-transistors (MOSFET).
42 . The circuit of claim 29 wherein the passive mixer or the transimpedance amplifier is formed from bipolar-CMOS (BiCMOS) or Silicon-Germanium (SiGe) process technology.
43 . The circuit of claim 30 wherein the input bipolar transistors of the transimpedance amplifier are parasitic bipolar transistors,