Dual gate cascode MESFETs and HEMTs with very high gain at low noise levels

摘要

For gain controllable amplifiers for with both low noise and high gain and for switching applications dual gate MESFETs and HEMTs have been fabricated and characterized. In comparison to single gate devices with the same gate dimensions, dual gate elements operated as a cascode circuit by RF-grounding of the second gate show significantly reduced feedback capacitance, higher output impedance and higher RF power gain. An extremely high associated gain of 22 dB with a low noise figure of 1 dB at 10 GHz has been obtained for quarter micron dual gate cascode PM-HEMTs. By applying a DC voltage swing of 2.6 V at the second gate electrode a dynamic range of 40 dB for the insertion loss/gain characteristic has been measured for dual gate cascode MESFETs.