Tunable matched filters for pulse-code modulation using charge-transfer devices

A tunable matched filter for the major PCM codes has been synthesized utilizing a developmental bucket-brigade delay (BBD) line. The variable delay feature of the BBD allows continuous tuning of the matched filter over a wide range of bit rates. By combining and weighting the outputs of two BBD lines, matched filters for nonreturn-to-zero (NRZ), return-to-zero (RZ), and biphase codes are realized with a signal-to-noise performance within 0.8 dB of theoretical.