4-quadrant power supplies or 4-quadrant amplifiers are electronic modules which generate both positive and negative voltages, and which can deliver and receive positive and negative currents. They can therefore be used as a source or a sink.
Power supplies for laboratory use are mostly only power supplies. They are only able to deliver power with one single polarity, i.e. these instruments only work in one quadrant of the voltage / current diagram.
Common amplifiers deliver voltages with both polarities, but are generally unable to absorb power values in a range comparable to that which they are able to deliver. They therefore mainly work as 2-quadrant instruments.
All 4-quadrant power supplies of the TOE 7621 series are additionally able to absorb power with both polarities corresponding to the delivered powers.
A 4-quadrant power supply of the TOE 7621 series is thus a bipolar voltage and current source as well as a current sink in one instrument. Use as a bipolar power amplifier is also possible.