A Unified Approach to the Design of Voltage-Controlled SAW Delay Lines

Abstract

Abstmct-A surface-acoustic-wave (SAW) variable-controlled delay line (VCDL), based on two chirp filters, is discussed and a unified analysis of all such VCDL configurations is presented. The system transfer function and delay formula are derived. Although the most general SAW-VCDL configuration consists of three controlling signals, it is shown that the delay introduced by the system depends only on the frequency of the signal that serves as an input to the mixer between the two chirp filters. The other two controlling signals affect the center frequency of the output spectrum and the system bandwidth, but not the delay. A new configuration of a SAW-VCDL, which uses two identical chirp filters, is then proposed and analyzed for two types of controlling signals. Laboratory experimental results are provided to support the analysis.