A Novel Wideband Programmable-Gain Amplifier based on Active-Feedback Technology

A new type of approach for programmable-gain amplifier (PGA) design with wideband and accurate dB-linear characteristic is presented. This circuit is based on the active-feedback bandwidth extension circuit structure, and the variation of voltage gain of this circuit can approach the pseudo-exponential function by using a binary-weighted switching technique without additional exponential generator. Therefore, compared with the traditional circuits, the proposed circuit can achieve wider −3dB bandwidth while obtaining wide digital dB-linear gain control, smaller gain error, smaller chip area and lower power consumption. The proposed PGA is simulated in a standard $0.18\mu\mathrm{m}$ CMOS technology. The gain ranges from −3.87 dB to 3.57 dB with a gain error less than ±0.017 dB. The frequency is almost flat up to 1GHz. The NF is around 12 dB and it consumes about 6.5 mW under a 1.8 V power supply.