Saw-Ccd Accumulating Correlator

A new analog-signal-processing device is reported in which a charge-coupled device (CCD) is coupled to a piezoelectric surface acoustic wave (SAW) delay line across a 300-nm gap. The CCD samples multiply, accumulate, and read out the cross-correlation function of two wide-band SAW input signals which counterpropagate on the delay line. A signal-processing gain of 30 dB at a bandwidth of 20 MHz has been observed by correlating biphase modulated pseudonoise waveforms of 100-μs duration in the presence of Gaussian noise. This compact hybrid structure provides 300 discrete samples of a 7-μs segment of the correlation function.