Abstract: An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

Abstract: An apparatus including: a first switch configured to provide a feed-forward path at an input of a first amplifier of a plurality of amplifiers coupled together at a single port, the feed-forward path configured to substantially reduce a leakage current into an input of a second amplifier of the plurality of amplifiers.

Abstract: An apparatus including: at least one differential amplifier configured to amplify a radio frequency signal; a mixer configured to mix the radio frequency signal from the at least one differential amplifier with a local oscillator signal; and a low-pass filter coupled to the mixer, the low-pass filter includes a capacitor and at least one variable resistor configured to tune the low-pass filter.

Abstract: Performing quadrature combining and adjusting including: a plurality of mixing circuits configured to generate a plurality of frequency converted signals; at least one mixing circuit of the plurality of mixing circuits is configured with a plurality of paths, each path representing one linearity mode; and a plurality of combining circuits configured to combine the plurality of frequency converted signals to generate a differential baseband output signal.

Abstract: An apparatus including: at least one receiver having injection points and having at least an amplifier and a transformer; and a plurality of isolation switches coupled to injection points of the at least one receiver, the plurality of isolation switches configured to route a calibration signal generated by a transmitter to one of the injection points.

Abstract: An apparatus including: at least one differential amplifier configured to amplify a radio frequency signal; a mixer configured to mix the radio frequency signal from the at least one differential amplifier with a local oscillator signal; and a low-pass filter coupled to the mixer, the low-pass filter includes a capacitor and at least one variable resistor configured to tune the low-pass filter.

Abstract: An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

Abstract: Performing quadrature combining and adjusting including: a plurality of mixing circuits configured to generate a plurality of frequency converted signals; at least one mixing circuit of the plurality of mixing circuits is configured with a plurality of paths, each path representing one linearity mode; and a plurality of combining circuits configured to combine the plurality of frequency converted signals to generate a differential baseband output signal.

Abstract: An apparatus including: at least one receiver having injection points and having at least an amplifier and a transformer; and a plurality of isolation switches coupled to injection points of the at least one receiver, the plurality of isolation switches configured to route a calibration signal generated by a transmitter to one of the injection points.

Abstract: An apparatus including: a first switch configured to provide a feed-forward path at an input of a first amplifier of a plurality of amplifiers coupled together at a single port, the feed-forward path configured to substantially reduce a leakage current into an input of a second amplifier of the plurality of amplifiers.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for performing quadrature combining and adjusting. One example circuit may include first through fourth mixing circuits. The first mixing circuit may multiply a radio frequency signal with a first local oscillating signal to generate a first frequency converted signal. The second mixing circuit may multiply a radio frequency (RF) signal with a second local oscillating signal, which may be about 90° out of phase with the first local oscillating signal, to generate a second frequency converted signal. The third and fourth mixing circuits may multiply the RF signal with the second and first signals, respectively, to generate third and fourth frequency converted signals, respectively. A first combining circuit may combine the first and third frequency converted signals, and a second combining circuit may combine the second and fourth frequency converted signals.

Abstract: Techniques are provided for reducing mismatch between the in-phase (I) and quadrature (Q) channels of a communications transmitter or receiver. In an exemplary embodiment, separate voltages are applied to bias the gates or bulks of the transistors in a mixer of the I channel versus a mixer of the Q channel. In another exemplary embodiment, separate voltages are applied to bias the common-mode reference voltage of a transimpedance amplifier associated with each channel. Techniques are further provided for deriving bias voltages to minimize a measured residual sideband in a received or transmitted signal, or to optimize other parameters of the received or transmitted signal. Techniques for generating separate bias voltages using a bidirectional and unidirectional current digital-to-analog converter (DAC) are also disclosed.

Abstract: Techniques are provided for reducing mismatch between the in-phase (I) and quadrature (Q) channels of a communications transmitter or receiver. In an exemplary embodiment, separate voltages are applied to bias the gates or bulks of the transistors in a mixer of the I channel versus a mixer of the Q channel. In another exemplary embodiment, separate voltages are applied to bias the common-mode reference voltage of a transimpedance amplifier associated with each channel. Techniques are further provided for deriving bias voltages to minimize a measured residual sideband in a received or transmitted signal, or to optimize other parameters of the received or transmitted signal. Techniques for generating separate bias voltages using a bidirectional and unidirectional current digital-to-analog converter (DAC) are also disclosed.