Instrumentation Amplifier

The instrumentation amplifier greatly amplifies differential signals but amplifies as least as possible common signals, which has the effect of filtering them out of the output signal. The amplifier circuit is a 4-channel version of the three op-amp instrumentation amplifier circuit, as seen in figure 3. This amplifier circuit is configured with a gain of 1000. To make sure the least amount of DC differential noise is passed on, the Rr resistors have a tight tolerance of 1%.

Figure 3: Instrumentation Amplifier Schematic

In our first prototype, this configuration was found to significantly degrade the signal and so the circuit will need to be tweaked or the instrumentation amplifier circuit replaced with instrumentation amplifier ICs.