A 3.35 microsecond HACT transversal filter

A heterojunction acoustic charge transport (HACT) transversal filter with a 3.35- mu s integration time is reported. This is the longest acoustic charge transport device reported to date. The device operates at an acoustic clock frequency of 144 MHz and at an acoustic power of 100 mW. The output signal is generated by 480 equally weighted taps. The multiple output tap structure results in the device exhibiting 12 dB of gain when embedded in a 50- Omega system. Measurements of the 1-dB compression point, the third-order intercept, and the noise floor show the dynamic range of the device to be in excess of 80 dB over the 300-kHz bandwidth of the filter. >