Abstract: An apparatus for modifying a radio frequency signal includes a mixer core, an input circuit and an interface circuit. The mixer core receives a first signal having a first frequency and a second signal having a second frequency, and outputs a third signal which is a function of the first and second signals. The input circuit sets a predetermined bias current, receives a radio frequency (RF) signal and inputs the RF signal into the mixer core. The interface circuit is interposed between the mixer core and the input circuit. The interface circuit receives the bias current and input it to the mixer core. In one embodiment, the input circuit includes a transistor and the interface circuit includes a transformer.

Abstract: A communications device includes a direct-conversion receiver for a radio frequency (RF) signal which is configured to receive the RF signal during defined time slots. A first input receives the RF signal and a first output outputs a baseband signal derived from the RF signal. A mixer module is configured to receive the RF signal and a local signal which is generated by a local oscillator. The mixer module generates an output signal which includes the baseband signal and an offset component. An amplifier module is connected between the first output and the mixer module, and includes a feedback loop which has in a backward path, a track-and-hold circuit. The track-and-hold circuit is configured to track the offset component during a first time slot and to hold a value of the offset component at an end of the first time slot until a subsequent second time slot begins. This held value is applied during the second time slot to the output signal in order to provide for fast compensation of the offset component.

Abstract: Disclosed is an apparatus for modifying a radio frequency signal. In one embodiment, the apparatus includes a mixer, an amplifier module and an interface circuit. The mixer is configured to receive a first signal having a first frequency and a second signal having a second frequency, and to output a third signal which is a function of the first and second signals. The amplifier module includes a first amplifier stage and a second amplifier stage and is configured to amplify a communications signal which is then input into the mixer as the first signal. The first and second amplifier stages are in communication via a first signal path and a second signal path. The interface circuit is interposed between the mixer and the amplifier module, and inserted into the second signal path so that a DC bias current flows from the first amplifier stage through the interface module into the second amplifier stage.