Integrated dual transistor SHF amplifier - has resistive or inductive input with symmetrical FET's capacitatively cross coupled between gate and drain operated in common source mode

摘要

The high frequency amplifier (up to 10 GH3) consists of two gallium arsenide field effect transistors which are cross coupled by on chip capacitors between their gates and drains. The capacitors are produced using a chip area of similar dimensions to the transistors at these frequencies and the impedance may be set to be real or inductive at will. Inductive compensation is required for the capacitative output impedance but this is more easily provided at a power stage where dimensions are less crucial. The transistors are integrated in mirror symmetry with their sources common and gate to drain resistors are incorporated. Each drain metallisation partially covers the others gate metalisation with a spacing dielectric layer or vice versa. The amplifier is driven symmetrically with the input signal between the two gates and the output is taken between the two drains. The effect of the coupling capacitor on the output capacitance is to modify it by less than the mutual coupling capacitance. Each transistor operates in common source mode.