Abstract: In the wireless receiver, in order to ensure that AGC loop has the same transient response and the exact settling time, when signal power are different, the VGA gain is realized according to the exponential changes. Therefore, a programmable CMOS exponential function generator for AGC applications are presented, which is based on the differential transconductor circuit, square circuit and multiplier. The method of the fourth-order Taylor approximation is adopted in the function generator, and the different exponent function can be approximated accurately by the controlled external offset voltage. The proposed circuit is simulated and analyzed by PSPICE with TSMC 0.5 μm CMOS technology parameters, the results show that a nearly 40 dB output dynamic range is obtained with the error less than ±0.5 dB over an input range-1.54 ≤ x ≤ 3.15, and the different exponent function can be implemented and programmed, which are very suitable for application to the high performance AGC system implementation.