Improved high input impedance mV-amplifiers with gain factors from 10 to 900

New mV-amplifiers driving a planar multijunction thermal converter (PMJTC) at their output have been developed to measure the output voltage of micropotentiometers (mupots). Using a twin-stage design with gains of 10, 20 and 30 per stage, total gain factors from 10 to 900 are achieved. This results in a usable range of input voltages from 100 muV up to 100 mV at frequencies from dc to 1 MHz. A novel offset compensation allows reliable operation also at higher gain factors. The ac-dc transfer difference if flat to within plusmn 300 muV/V up to 1 MHz.