Forcing Voltage Source

A simple circuit for when we want to force an accurate voltage across a load (rightmost pot) despite line resistance. The horizontal potentiometer represents the line resistance on the forcing path (connected on the output of leftmost OPAMP). The rightmost potentiometer represents the load on which we wish to force a specific voltage across. The leftmost OPAMP senses the voltage across the load through the sense path (connected to negative input of leftmost OPAMP) and adjusts its output to equate its inputs. The voltage we wish to set would be set at the reference voltage source at the positive input. It is important to note that line resistance is not futile for the sense path (as demonstrated by the resistor). The top OPAMP represents a programmable gain amplifier and senses the current through the load. The current through the internal 1k sense resistor is the same as the current through the pot load. 1mV : 1mA Everything from the left of the mid potentiometer is internal to this forcing voltage circuit. The rest is either load/line resistance and is external. It is also important to note that the forcing OPAMP's voltage rails are set to giga volts for the purpose of this demo. Additional circuitry is required for practical and realistic implementation.

published 5 years ago