A 32 tap digitally controlled programmable transversal filter

Abstract

A digitally controlled programmable transversal filter (DCPTF) has been developed that uses a 32-tap LiNbO/sub 3/ delay line and two LSI GaAs ICs to digitally control tap weight magnitude and sign. Compared to previously reported PTR devices, this third-generation device is significantly reduced in size and power, yet retains state-of-the-art performance. The device is completely programmable, constrained only by the bandwidth (100 MHz centered at 100 MHz) and the number of taps. The DCPTF is designed in 16-tap blocks to easily expand the number of taps. A calibration method is presented which removes nonideal GaAs FET (field-effect transistor) array gain states due to process variations. The on/off ratio of each individual tap is greater than 35 dB. The DCPTF is demonstrated as a bandpass filter with programmable center frequency and bandwidth.<>