Abstract:
A method for reciprocal-mixing noise cancellation may include receiving, from a first mixer, a first signal comprising a wanted signal at a first frequency and a modulated signal at a second frequency. The modulated signal may be a product of a reciprocal-mixing of an unwanted signal with a phase noise. One or more portions of the modulated signal may overlap the wanted signal, adding a reciprocal-mixing noise to the wanted signal. A second signal may be generated by mixing, at a second mixer, the first signal with a third signal, which is at a third frequency related to a blocker offset frequency. A gain may be applied to the second signal to generate an amplified second signal that may be subtracted from the first signal to generate a fourth signal. The fourth signal may be filtered to generate the wanted signal at the first frequency without the reciprocal-mixing noise.
Abstract:
A method for reciprocal-mixing noise cancellation may include receiving a baseband signal down-converted to baseband using a local oscillator (LO). The baseband signal may comprise a wanted signal and a reciprocal mixing noise, which at least partially overlaps the wanted signal and is due to mixing of a blocker signal with a phase noise of the LO. Blocker recovery may be performed on the baseband signal and a blocker estimate signal may be generated from the baseband signal. The phase noise of the LO may be measured and used in generating a phase noise measurement signal. The blocker estimate signal and the phase noise measurement signal may be processed to generate a reconstructed noise signal that may comprise the overlapping reciprocal mixing noise. The reconstructed noise signal may be subtracted from the baseband signal to provide the wanted signal free from to the reciprocal mixing noise.
Abstract:
According to one embodiment, a compact low-power receiver comprises a front-end producing a front-end gain and a back-end producing a back-end gain. The front-end includes a transconductance amplifier providing digital gain control and outputting an amplified receive signal, a mixer for generating a down-converted signal from the amplified receive signal, and a transimpedance amplifier (TIA) including a current mode buffer. The TIA provides gain control for amplifying the down-converted signal to produce a front-end output signal. In one embodiment, the back end includes a second-order low-pass filter to produce a filtered signal from the front-end output signal and an analog-to-digital converter (ADC), wherein the filtered signal is fed directly to the ADC without direct-current (DC) offset cancellation being performed. In various embodiments, the front-end gain is substantially greater than the back-end gain.
Abstract:
According to one embodiment, a compact low-power receiver comprises first and second analog circuits connected by a digitally controlled interface circuit. The first analog circuit has a first direct-current (DC) offset and a first common mode voltage at an output, and the second analog circuit has a second DC offset and a second common mode voltage at an input. The digitally controlled interface circuit connects the output to the input, and is configured to match the first and second DC offsets and to match the first and second common mode voltages. In one embodiment, the first analog circuit is a variable gain control transimpedance amplifier (TIA) implemented using a current mode buffer, the second analog circuit is a second-order adjustable low-pass filter, whereby a three-pole adjustable low-pass filter in the compact low-power receiver is effectively produced.
Abstract:
A circuit for a low-loss duplexer with noise cancellation in a receive (RX) path of a transceiver includes a duplexer, a balancing network, and a noise cancellation circuit. The duplexer circuit is coupled to an antenna of the transceiver. The balancing network is coupled to the duplexer and provides an impedance matching an impedance associated with the antenna. The noise cancellation circuit senses a noise signal generated by the balancing network and uses the sensed noise signal to improve a signal-to-noise ratio (SNR) of the RX path.
Abstract:
A transceiver circuit including a digital-to-analog converter, a filter coupled to the digital-to-analog converter, a passive mixer coupled to the filter, via a buffer and a multi-stage power amplifier coupled to the passive mixer via a passive amplifier. A transmitter and method for amplifying a RF signal for transmission are also provided.
Abstract:
An RF front-end with on-chip transmitter/receiver isolation using a gyrator is presented herein. The RF front end is configured to support full-duplex communication and includes a gyrator and a transformer. The gyrator includes two transistors that are configured to isolate the input of a low-noise amplifier (LNA) from the output of a power amplifier (PA). The gyrator is further configured to isolate the output of the PA from the input of the LNA. The gyrator is at least partially or fully capable of being integrated on silicon-based substrate.
Abstract:
Aspects of a method and system for a low-noise, highly-linear receiver front-end are provided. In this regard, a received signal may be processed via one or more transconductances, one or more transimpedance amplifiers (TIAs), and one or more mixers to generate a first baseband signal corresponding to a voltage at a node of the receiver, and a second baseband signal corresponding to a current at the node of the receiver. The first signal and the second signal may be processed to recover information from the received signal. The first signal may be generated via a first one or more signal paths of the receiver and the second signal may be generated via a second one or more signal paths of the receiver.
Abstract:
A circuit for a low-loss electrical balance duplexer (EBD) with noise cancellation may include an EBD circuit. The EBD circuit may be coupled to one or more output nodes of a transmit (TX) path, an antenna, and a one or more input nodes of a receive (RX) path. The EBD circuit may be configured to isolate the TX path from the RX path, and to provide low-loss signal paths between the one or more output nodes of the TX path and the antenna. A balancing network may be coupled to the EBD circuit and configured to provide an impedance that matches an impedance associated with the antenna. A noise cancellation circuit may be configured to sense a noise signal generated by the balancing network, and to use the sensed noise signal to improve a signal-to-noise ratio (SNR) of the RX path.
Abstract:
A circuit for a low-noise interface between an amplifier and an analog-to-digital converter (ADC) may comprise a capacitor element having a capacitance of C coupled between a first and second output node of the amplifier. A first resistor R1 may be coupled in parallel with the capacitor. A second resistor R2 may be coupled between the first output node of the amplifier and a first input node of the ADC. A third resistor R3 may be coupled between the second output node of the amplifier and a second input node of the ADC. Initial values of the resistances R1, R2, and R3 may be selected to provide a desired value RL for a load resistance of the amplifier. A value of the capacitance C may be selected so that, in combination with the desired value RL, a desired bandwidth for the amplifier is achieved.