Programmable measurement amplifier PGA circuit principle diagram

The programmable measuring amplifier has additional analog switches and drive circuits than the measuring amplifier. The gain selection switches Sl-S'l, S2-S'2, S3-S'3 operate in pairs. Only one pair of switches is closed at each moment. When the digital input code is changed, the closed switch number can be changed, and the selected Different feedback resistors are equivalent to automatically changing the resistance of the potentiometer R1 in the measurement amplifier to achieve the purpose of changing the amplifier gain.

Transfer files for PCB proofing

The figure below shows the internal circuit schematic diagram of the integrated programmable measurement amplifier circuit chip LH0084. On the one hand, the feedback resistor of the operational amplifier A3 is selected through wiring to determine the basic amplification factor of the amplifier. On the other hand, automatic control of the amplification factor is achieved by controlling the analog switch.