A Simple Circuit to Reduce the Input Capacitance of Microelectrode Amplifiers

There are several specialized applications which require amplifiers with very low input capacitance. Two field effect transistors (FET's) can be cascaded in a source follower configuration to drive the drain of the input FET. The cascaded source follower provides at least an order of magnitude decrease in input capacitance. The cascaded source follower can be added to existing amplifiers or incorporated into new amplifier design with relatively little difficulty.