Apparatus and methods for eliminating DC offset in a wireless
communication device operable on a continuous basis or on a sampled
basis. In a receive channel, the output of a forward variable gain
amplifier is fed back to an RC circuit to charge the capacitor (C) to a
voltage dependent on the DC offset in the variable gain amplifier output.
The voltage on the capacitor is amplified and summed with the input to
the variable gain amplifier. The RC circuit is configured to provide a
high gain feedback at DC and very low frequencies, but very low gain at
signal frequencies. Preferably the output of the forward variable gain
amplifier is fed back to the RC circuit with a gain that is inversely
proportional to the forward gain. Disconnection of the capacitor and
feedback of the capacitor voltage provides sampled operation. Various
embellishments and sample applications are disclosed.