A digitally controlled amplifier (DCA) has a drive (e.g., bipolar junction) transistor with a base to accept an input signal and a collector to supply an output signal. The DCA also includes n switchable gain amplifier networks (SGANs). Each SGAN has a signal input connected to the collector of the drive transistor, an input to accept a logic signal, and a signal output to supply a switchable gain AC output signal to a load in response to the logic signal. The SGAN signal outputs are connected together, typically in parallel, to supply a digitally controlled AC output gain. An auxiliary SGAN may be connected to supply a constant gain AC output signal. Each of the SGANs may have an identical switchable AC gain and accept an independent logic signal to supply (n+1) levels of digitally controlled AC output gain.