A binary-weighted 64-dB programmable gain amplifier with a DCOC and AB-class buffer

This paper designs a binary-weighted programmable gain amplifier (PGA) with a DC offset cancellation (DCOC) circuit and an AB-class output buffer. The PGA adopts the circuit topology of a differential amplifier with diode-connected loads. Simulation shows that the performance of the PGA is not sensitive to temperature and process variation. According to test results, controlled by a digital signal of six bits, the PGA can realize a dynamic gain of -2 to 61 dB, and a gain step of 1 dB with a step error within 0.38 dB. The minimum 3 dB bandwidth is 92 MHz. At low-gain mode, IIP3 is 17 dBm, and a 1 dB compression point can reach 5.7 dBm. The DCOC circuit enables the amplifier to be used in a direct-conversion receiver and the AB-class output buffer circuit reduces the overall static power consumption.