Apparatus and methods for vector modulator phase shifters are provided. In certain embodiments, a phase shifter includes a quadrature filter that filters a differential input signal to generate a differential in-phase (I) voltage and a differential quadrature-phase (Q) voltage, an in-phase variable gain amplifier (I-VGA) that amplifies the differential I voltage to generate a differential I current, a quadrature-phase variable gain amplifier (Q-VGA) that amplifies the differential Q voltage to generate a differential Q current, and a current mode combiner that combines the differential I voltage and the differential Q voltage to generate a differential output signal. A phase difference between the differential output signal and the differential input signal is controlled by gain settings of the I-VGA and the Q-VGA.

A transmitter circuit is disclosed. The transmitter circuit includes a frequency circuit configured to generate a frequency signal, a power amplifier configured to drive an antenna with a drive signal according to the frequency signal, and a programmable delay circuit configured to controllably extend a propagation delay between the frequency signal generated by the frequency circuit and the drive signal of the power amplifier. The programmable delay circuit is programmed with a programming value which causes the transmitter circuit to pass a calibration test.

A transmitter circuit is disclosed. The transmitter circuit includes a frequency circuit configured to generate a frequency signal, a power amplifier configured to drive an antenna with a drive signal according to the frequency signal, and a programmable delay circuit configured to controllably extend a propagation delay between the frequency signal generated by the frequency circuit and the drive signal of the power amplifier. The programmable delay circuit is programmed with a programming value which causes the transmitter circuit to pass a calibration test.

Apparatus and methods for vector modulator phase shifters are provided. In certain embodiments, a phase shifter includes a quadrature filter that filters a differential input signal to generate a differential in-phase (I) voltage and a differential quadrature-phase (Q) voltage, an in-phase variable gain amplifier (I-VGA) that amplifies the differential I voltage to generate a differential I current, a quadrature-phase variable gain amplifier (Q-VGA) that amplifies the differential Q voltage to generate a differential Q current, and a current mode combiner that combines the differential I voltage and the differential Q voltage to generate a differential output signal. A phase difference between the differential output signal and the differential input signal is controlled by gain settings of the I-VGA and the Q-VGA.

An apparatus is disclosed for oscillator leakage calibration. In example aspects, the apparatus includes a mixer circuit and calibration circuitry. The mixer circuit has a first stage including at least one transistor coupled between a mixer input and a mixer output and a second stage including one or more transistors coupled between the at least one transistor and the mixer output. The mixer circuit also has tuning circuitry coupled to the at least one transistor. The calibration circuitry includes at least one resistor coupled between a power distribution node and at least one mixer node, with the at least one mixer node coupled between the at least one transistor and the one or more transistors, and at least one switch coupled between the power distribution node and the at least one mixer node. The calibration circuitry also includes controller circuitry coupled between the mixer node and the tuning circuitry.