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The overall gain (V/A) can be adjusted across a wide range by combining the gains of individual opamps and the value of the shunt resistor. Cascading two lower-gain opamps allows for increased bandwidth compared to using a single opamp with high gain. The amplifier is powered by either a CR2032 battery or its rechargeable counterpart, the LIR2032, with the negative rail of the symmetrical power supply generated by an LM2664 charge pump. Diodes D1 and D2 are optional and serve to reduce the supply voltage to meet the operational amplifiers' working range, typically 5.5V. IC4 and LED1 provide an optional indicator for battery depletion. I designed the PCB layout for the opamps in SOT23-5 packages, accommodating both normal and reverse pinouts.
Current consumption: 2,2mA @ 3V
Bandwidth (-3dB): 55kHz (2 x MCP6V81U, first stage gain: 100, second stage gain: 10)