The Use of Transistors as Broadband Voltage-Variable Time Delays

摘要

A mathematical model is developed that describes the variable time-delay performnce of a high-frequency transistor amplifier. Time-delay change is achieved by voltage variation of the minority-carrier transit time and the collector capacitance of the transistor. A figure of merit clarifies the relationship between time delay and amplifier bandwidth and is used to obtain maximum utilization of the voltage-variable transistor parameters. Other delay techniques, specifically the LC lumped approximate transmission-line section, provide voltage-variable continuous time delay, using only a variable capacitance. Comparison between the transistor and LC techniques shows that using changes in transit time of ordinary HF transistors offers little advantage over the LC technique. (Author)