A 1.8V 250MHz CMOS Programmable Gain Filter for Ultra-wideband Transmitter System

In this paper, a 250MHz, CMOS programmable gain low pass filter for ultra-wideband transmitter is presented. The programmable gain network that is programmed by decoder will be utilized to control the gain of filter. In order to reach sufficient attenuation, the 8^rdGm-C chebyshev low pass filter base on leap-frog topology is employed. Simulation results with CMOS 0.18μm technology show that the gain can be programmed from-14dB to -32dB with 2dB step, step accuracy and absolute accuracy are ±0.15 and ±0.25. The THD of programmable gain filter is -40dB for lVpp input signal and power dissipation is 15.7mW under 1.8V power supply.