Multiple decade voltage selector - uses few precision resistors with summing amplifier output for instrumentation use

摘要

The multiple-decade voltage divider circuit comprises a potential divider network of nine resistors (R1-R9) across a reference voltage supply (Un). Parallel-connected single-pole switches - one for each decade- are used to select the desired combination of resistors. The output of each decade switch is connected to the non-inverting input of an operational amplifier (SP1). Each amplifier acts as a buffer between the switch and the load circuit. The output load resistor for each amplifier is a summing resistor (1/1OR, R, 1OR), the summing point being connected to the inverting input of a further operation amplifier.