Analog Signal Processing Using Surface Wave and Charge Transfer Devices

Two viable component technologies currently exist for implementing analog signal processing at VHF and UHF, namely, surface wave devices (SWD´s) and charge transfer devices (CTD´s). A review of each technology will be given along with relevant advantages, disadvantages, and ranges of important operating parameter for each. Under SWD´s, primary emphasis will be given to the practical surface wave filters as well as to monolithic programmable matched filters using MOSFET detectors for surface wave taps on a silicon substrate, and the selectable bandpass filter in which programmable techniques are employed to obtain variable bandwidth and variable center frequency surface wave bandpass filters. The discussion of CTD´s will include both charge coupled devices and bucket brigade devices (BED´s). Application will be discussed for variable frequency bandpass filters, programmable matched filters, and variable tap weight transversal filters for adaptive filtering such as telephone channel equalization. A comparison of the present and projected advantages and also limitations of these two technologies will be discussed.