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目前用于微波控制电路的半导体器件主要是PIN管,然而,随着微波器件和微波技术的改进,微波部件不仅应有较宽的频率特性,同时还需具有体积小、重量轻、成本低的特点。近几年来,随着GaAs MESFET性能的不断提高、成本明显降低,使MESFET在微波控制电路方面具有令人振奋的应用前景,且已取得了许多可喜的成果。同样,在属于微波控制电路的衰减器方面,现已研究出GaAs MESFET数字控制和模拟控制单片微波衰减器。 MESFET用于衰减工作模型时,与放大、振荡,变频等场合不同,器件的源-漏之间并无直流偏压,而是作为微波信号的通道,器件仅以改变栅偏压Vg来控制器件的阻抗变化,使MESFET作为电调可变电阻。当栅偏压Vg=0时,栅下空间电荷层薄,沟道是开通的,器件的源-漏之间呈低阻抗状态;当|Vg|大于夹断电压|Vg|时,栅下沟道已全部耗尽,构成
However, with the improvement of microwave devices and microwaves, the microwave components should not only have wider frequency characteristics, but also have the advantages of small size, light weight and low cost Features. In recent years, as the performance of GaAs MESFET continues to increase, the cost is significantly reduced, making MESFET an exciting application prospect in microwave control circuits and many promising achievements have been made. Similarly, GaAs MESFET digitally controlled and analog-controlled monolithic microwave attenuators have been developed for attenuators belonging to microwave control circuits. MESFET used to attenuate the working model, and amplification, oscillation, frequency conversion and other occasions, the device source-drain there is no DC bias, but as a microwave signal channel, the device only to change the gate bias Vg to control the device The impedance changes, so MESFET as ESC variable resistor. When the gate bias Vg = 0, the gate space charge layer is thin, the channel is open, the source and drain of the device is in a low impedance state; when | Vg | is greater than the pinch-off voltage | Vg | Road has been exhausted, constitute