Abstract: A programmable gain amplifier (10) has a differential input (12-13), a differential output (16-17), and a plurality of enable inputs (21, 31-34). The amplifier includes a plurality of transconductor sections (26-29), which each have input nodes coupled to the differential input, output nodes coupled to the differential output, and an enable node coupled to a respective enable signal. The transconductor sections have different gains, which are respective powers of two. Each transconductor section includes a transconductor circuit (51, 56) which is coupled in series with at least one current mirror circuit (52-53, 57-58). Each transconductor circuit has a transistor (121) with a class A quiescent current that is proportional to the corresponding gain, the transistor being sized to achieve an optimum current density for its quiescent current.