Microwave Acoustic Bulk Device Technique Studies.
Interim rept. 1 Nov 74-30 Apr 75,
STANFORD UNIV CALIF MICROWAVE LAB
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In the previous report results on a ZnO on Si convolver were described, where a conversion efficiency of - 55 dBm was obtained. During the reporting period a new type of broadband matching network which makes it possible to increase the bandwidth of the interdigital transducers from 8 to 22 MHz were designed and tested. New types of diffusion layer transducers using p elements laid down in Si were also tested these can be switched on and off by incident light or by changing an applied dc potential. The work on the diffusion layer transducers to improve their efficiency is also continuing, and to use a new dc sputtering station to make more reproducible convolver devices is also intended. In the last report a new approach to analogdigital conversion was introduced. It operates by comparing a reference signal, having a linearly varying amplitude versus time, with the analog input signal whose amplitude is to be digitized. The reference signal is produced by passing an rf tone pulse through an interdigital acoustic wave transducer. The basic convolution property of the transducer results in the production of the required linearly varying ramp. An integrated circuit comparator and counter are used to produce the digital readout. During the reporting period a first experimental model has been constructed, utilizing a 50 MHz surface acoustic wave delay line, and using four-bit words, which has established the principle of the device.
- Line, Surface and Bulk Acoustic Wave Devices
- Solid State Physics