A signal processing system and method. The inventive system includes a first
circuit
for distributing an input signal between two or more channels in a current mode
of operation. A second circuit is disposed in each of the channels for processing
the input signal and providing an output signal in response thereto. A third circuit
is provided to combine the signals output by the processing circuit. A fourth circuit
is included for controlling the first and the third circuits. In a specific illustrative
embodiment, the system further includes a radio frequency stage for downconverting
a received signal and providing the input signal in response thereto. In the specific
embodiment, the first circuit includes a mixing circuit. The mixing circuit includes
Gilbert cells and circuitry for providing automatic gain control for each of the
channels individually. The Gilbert cells and the automatic gain control circuitry
are driven by a transconductance amplifier and therefore operate in a current mode.
Differential digital automatic gain control signals are provided in response to
a channel select signal from a digital control circuit. The inventive circuit provides
multiple IF channels which may be filtered individually. The invention thereby
provides wide band operation in a simple, single stage implementation that consumes
little power. Further, the current mode thereof is effective in the reduction of
insertion loss.