A filter module for reducing a DC offset voltage in a radio frequency communication
channel is described. A first capacitor is coupled between a first differential
input node and a first differential output node. A second capacitor is coupled
between a second differential input node and a second differential output node.
An active variable resistor is coupled between the first differential output node
and the second differential output node. The active variable resistor receives
a control signal. The control signal adjusts the value of the active variable resistor,
which adjusts the frequency response of the filter module. The rate at which the
filter module reduces DC offset voltages is thereby adjusted. The filter module
is also adaptable to single-ended applications.