Abstract: A signal handling stage provides variable gain, for example for automatic gain control functions, in a radio frequency tuner. The stage comprises a transconductance stage having negative feedback via further transconductance stage. The output current of the transconductance stage is supplied to an AGC core, which steers the output current between output loads and loads for driving the transconductance stage in accordance with an AGC voltage. The amount of negative feedback is therefore varied in accordance with the AGC voltage. For relatively low gain, a large amount of feedback is used and this improves the distortion performance. For relatively high gain, the negative feedback is reduced but a good noise figure can be achieved.

Abstract: A radio frequency amplifier including a long tail pair of transistors provided with a tail current source. The bases of the transistors are driven by emitter follower transistor provided with collector load resistors. Feedback capacitors ensure stability and feedback resistors bias the amplifier without degrading noise performance. The amplifier may be driven unbalanced while retaining good second harmonic distortion performance.

Abstract: An amplifier, for example for use as an LNA of a radio frequency tuner, comprises a differential amplifying stage provided with an AGC core. The output signals are formed across load resistors at differential outputs. Compensating stages sum the signals at the differential outputs and subtract the resulting sum signal from the output signals so as to cancel the common mode signals including second order distortion products.

Abstract: A signal handling stage provides variable gain, for example for automatic gain control functions, in a radio frequency tuner. The stage comprises a transconductance stage having negative feedback via further transconductance stage. The output current of the transconductance stage is supplied to an AGC core, which steers the output current between output loads and loads for driving the transconductance stage in accordance with an AGC voltage. The amount of negative feedback is therefore varied in accordance with the AGC voltage. For relatively low gain, a large amount of feedback is used and this improves the distortion performance. For relatively high gain, the negative feedback is reduced but a good noise figure can be achieved.

Abstract: A radio frequency amplifier including a long tail pair of transistors provided with a tail current source. The bases of the transistors are driven by emitter follower transistor provided with collector load resistors. Feedback capacitors ensure stability and feedback resistors bias the amplifier without degrading noise performance. The amplifier may be driven unbalanced while retaining good second harmonic distortion performance.

Abstract: An input interface is provided for interfacing between a radio frequency input, for example from a cable distribution network, and a plurality of radio frequency tuners. The interface comprises a broadband active multipath non-reactive power splitter having an input for receiving a broadband radio frequency signal and a plurality of differential outputs. The splitter further has an active power splitting circuit which supplies the broadband radio frequency signal to each of the outputs via a channel comprising an automatic gain control circuit having a single-ended output connected to the input of a differential output buffer.