This cryogenic amplifier/buffer has a single coax (SMA) connector for combined output/supply/sample-dcbias.
The ac voltage gain is 2V/V (in 50 ohm load) from 100kHz to 2GHz (powergain is high as the input is high impedance).
Input resistance is >1M, inputcapacitance is 1pF. Output drives a 50 ohm coax.
The design is based on a discrete HEMT-input stage, care should be taken not to damage the input by overloading it
(0.5Vpp maximum).
The amplifier contains no chopper or oscillating circuits that could produce interference
Power for 2GHz bandwidth: 0.8mW (0.2mW in HEMT + 0.6mW in dc-resistor)
moving dc-resistor to another heatsinkpoint (still) can result in 0.2mW for amp
Lower dissipation for lower bandwidths.
The amplifier is connected for both signal and supply via only 1 coax line.
On this line dc-power is send via a bias-tee box. Hemt supply and a dc-bias can be set via the BNC-input on the bias-tee, HEMT and bias dc-current can be monitored via the other BNC
