5. Open amplifier

Open amplifier symbol

The open amplifier equals in principle the summer circuit except for the missing feedback resistor. The input network is still present.

Most commonly, open amplifiers are used in combination with complex functions.

This is usefull in order to generate inverse functions, for example a multiplier in comination with an open amplifier can performe division.

The THAT does not have explicit open amplifiers, but gives the possibility to convert a summer to an open amplifier by simply connecting the FB-panel with the ground panel directly below.