Dual-Gate Mesfet Variable-Gain Constant-Output Power Amplifier

摘要

Phase I of this study proved the feasibility of the variable-gain, constant-output power amplifier from the chosen approach by demonstrating a breadboard model. During Phase II, the development of the final packaged amplifier with improved performance, the following tasks were completed: (1) a dual-gate FET amplifier was redesigned to obtain more gain (10 dB) over the band; (2) a video amplifier was designed and developed for higher gain (40 dB); and (3) circulators were eliminated to reduce the size of the amplifier. This amplifier was demonstrated to operate over a 3-GHz band (4.5 to 7.5 GHz) and to provide an output power of 3 + or - 2 dBm over its entire dynamic range of -45 to 0 dBm of input power. The linear ACG amplifier developed under this program has the following key features. (1) It preserves amplitude modulation of the incoming signal. (2) It can perform normal AGC function under a multiple-pulse condition. This characteristic may prove to be very useful for handling multiple threats. (3) It is very versatile. It can provide separate ports to facilitate output power level adjustment and input signal detection and monitoring. (4) It has very fast response. The rise time and fall time of this amplifier are better than 15 ns which is limited by the measurement system.