Abstract: Apparatus, systems, and methods are described that implement techniques for estimating a relative rotation between a first complex signal and a second complex signal. In apparatus form, a rotation-estimation circuit includes a first quadrant detector and receives the first and second complex signals and produces an estimate of the relative rotation between the complex signals. A variable rotator receives the estimate of the relative rotation and rotates at least one of the first and second complex signals using the estimate of the relative rotation. In method form, a first quadrant estimate is calculated that corresponds to the relative rotation between the first and second complex signals, and at least one of the first and second complex signals is rotated using the quadrant estimate of the relative rotation.

Abstract: A Doherty power amplifier is provided that includes a main amplifier device and an auxiliary amplifier device. The Doherty power amplifier further includes a phase compensation network. The phase compensation network is configured to maintain a substantially constant phase of one of an output signal from the main amplifier device or an output signal from the auxiliary amplifier device across a range of input powers. The Doherty power amplifier further includes an impedance inverter for power combining an output signal of the main amplifier device with an output signal of the auxiliary amplifier device.

Abstract: A transconductance cell is disclosed that includes a first transistor and a second transistor. A regulator regulates an average voltage in response to a reference voltage, where the average voltage corresponds to the average of a voltage at a bias terminal of the first transistor and a voltage at a bias terminal of the second transistor. A mixer including the transconductance cell is also disclosed. In the mixer, the transconductance cell receives a differential input voltage and produces a differential output current. The mixer also includes one or more switches that multiply the differential output current with an oscillator signal. A method is disclosed that includes measuring an average voltage of a voltage at a bias terminal of a first transistor and a voltage at a bias terminal of a second transistor and regulating the average voltage responsive to the measured average voltage and a reference voltage.

Abstract: A Doherty amplifier that includes a main amplifier device and an auxiliary amplifier device. The main amplifier device includes a plurality of independently controllable amplifier segments. The system further includes a coupler for coupling an input signal to each of the main amplifier device and the auxiliary amplifier device. The system further includes an impedance inverter for power combining an output signal of the main amplifier device with an output signal of the auxiliary amplifier device.

Abstract: Circuits, methods, and systems are provided for opening a primary feedback loop in a transmitter. An auxiliary feedback loop can be closed when the primary feedback loop is opened, and a controller can match a gain of the primary feedback loop to another gain in the transmitter.

Abstract: A transconductance cell is disclosed that includes a first transistor and a second transistor. A regulator regulates an average voltage in response to a reference voltage, where the average voltage corresponds to the average of a voltage at a bias terminal of the first transistor and a voltage at a bias terminal of the second transistor. A mixer including the transconductance cell is also disclosed. In the mixer, the transconductance cell receives a differential input voltage and produces a differential output current. The mixer also includes one or more switches that multiply the differential output current with an oscillator signal. A method is disclosed that includes measuring an average voltage of a voltage at a bias terminal of a first transistor and a voltage at a bias terminal of a second transistor and regulating the average voltage responsive to the measured average voltage and a reference voltage.

Abstract: A circuit is provided that includes a Cartesian feedback loop. The Cartesian feedback loop includes one or more operational amplifiers. At least one of the operational amplifiers includes two or more cascaded amplifier stages and one or more bypass amplifier stages. The bypass amplifier stages are connected in parallel with the cascaded amplifier stages.

Abstract: A circuit is provided that includes a Cartesian feedback loop. The Cartesian feedback loop includes one or more operational amplifiers. At least one of the operational amplifiers includes two or more cascaded amplifier stages and one or more bypass amplifier stages. The bypass amplifier stages are connected in parallel with the cascaded amplifier stages.

Abstract: A Doherty power amplifier is provided that includes a main amplifier device and an auxiliary amplifier device. The Doherty power amplifier further includes a phase compensation network. The phase compensation network is configured to maintain a substantially constant phase of one of an output signal from the main amplifier device or an output signal from the auxiliary amplifier device across a range of input powers. The Doherty power amplifier further includes an impedance inverter for power combining an output signal of the main amplifier device with an output signal of the auxiliary amplifier device.

Abstract: A Doherty amplifier that includes a main amplifier device and an auxiliary amplifier device. The main amplifier device includes a plurality of independently controllable amplifier segments. The system further includes a coupler for coupling an input signal to each of the main amplifier device and the auxiliary amplifier device. The system further includes an impedance inverter for power combining an output signal of the main amplifier device with an output signal of the auxiliary amplifier device.

Abstract: Circuits, methods, and systems are provided for opening a primary feedback loop in a transmitter. An auxiliary feedback loop can be closed when the primary feedback loop is opened, and a controller can match a gain of the primary feedback loop to another gain in the transmitter.

Abstract: An analog-to-digital converter is provided for producing digital signal representative of analog signals. Noise induced upon the digital signals can be substantially removed using a digital decimation filter. The decimation filter includes a front-end portion which receives the digital data at a relatively high sample rate and performs filtering operations with minimal complexity. Preferably, the front-end portion includes at least one stage of filtering and more preferably at least two filter stages, each of which perform interpolation separate from decimation. According to one embodiment, the first stage of the front-end portion involves decimation and the latter stage or stages of that portion involves a combination of interpolation and decimation. The cumulative effect is to reduce the sample rate of the incoming data stream produced by, for example, a quantizer to a value which can be more easily manipulated by the back-end portion of the digital decimation filter.