Abstract: A circuit comprising: a first passive mixer (21) having mixer inputs configured to receive in-phase (I) and quadrature-phase (Q) differential signals; and a first differential sub-circuit (31). The first passive mixer is configured to switch the in-phase (I) and quadrature-phase (Q) differential signals to the first differential sub-circuit at a mixing frequency. The first differential sub-circuit (31) has a pair of differential inputs configured to receive the switched in-phase (I) and quadrature-phase (Q) differential signals from the first passive mixer (21), each input having a capacitance capable of storing a charge that depends on the switched in-phase or quadrature-phase signals. The circuit further comprises a charge canceller configured to supply, to at least one of: the mixer inputs; and the pair of differential inputs, an opposite charge compared with a charge that has been stored on the pair of differential inputs by the operation of the first passive mixer.

Abstract: A circuit comprising: a first passive mixer (21) having mixer inputs configured to receive in-phase (I) and quadrature-phase (Q) differential signals; and a first differential sub-circuit (31). The first passive mixer is configured to switch the in-phase (I) and quadrature-phase (Q) differential signals to the first differential sub-circuit at a mixing frequency. The first differential sub-circuit (31) has a pair of differential inputs configured to receive the switched in-phase (I) and quadrature-phase (Q) differential signals from the first passive mixer (21), each input having a capacitance capable of storing a charge that depends on the switched in-phase or quadrature-phase signals. The circuit further comprises a charge canceller configured to supply, to at least one of: the mixer inputs; and the pair of differential inputs, an opposite charge compared with a charge that has been stored on the pair of differential inputs by the operation of the first passive mixer.

Abstract: An embodiment of a baseband filter in a transmitter subsystem of a wireless device comprises an operational amplifier (op-amp), a pole circuit, a feedback capacitor, and an active device. The op-amp is adapted to produce an amplified signal that includes noise gain produced by the op-amp. The pole circuit is electrically coupled with an output terminal of the op-amp, and is adapted to receive the amplified signal and to attenuate the noise gain to produce a filtered, amplified signal. The feedback capacitor is electrically coupled between the first pole circuit and an input terminal of the op-amp, and is adapted to compensate for a phase shift produced by the pole circuit. The active device is electrically coupled with the pole circuit, and is adapted to amplify the filtered, amplified signal and to produce a baseband filtered output signal.

Abstract: An embodiment of a baseband filter in a transmitter subsystem of a wireless device comprises an operational amplifier (op-amp), a pole circuit, a feedback capacitor, and an active device. The op-amp is adapted to produce an amplified signal that includes noise gain produced by the op-amp. The pole circuit is electrically coupled with an output terminal of the op-amp, and is adapted to receive the amplified signal and to attenuate the noise gain to produce a filtered, amplified signal. The feedback capacitor is electrically coupled between the first pole circuit and an input terminal of the op-amp, and is adapted to compensate for a phase shift produced by the pole circuit. The active device is electrically coupled with the pole circuit, and is adapted to amplify the filtered, amplified signal and to produce a baseband filtered output signal.