<P> When the input is positive, it is amplified by the operational amplifier, which switches the diode on . Current flows through the load and, because of the feedback, the output voltage is equal to the input voltage . </P> <P> The actual threshold of the super diode is very close to zero, but is not zero . It equals the actual threshold of the diode, divided by the gain of the operational amplifier . </P> <P> This basic configuration has a problem, so it is not commonly used . When the input becomes (even slightly) negative, the operational amplifier runs open - loop, as there is no feedback signal through the diode . For a typical operational amplifier with high open - loop gain, the output saturates . If the input then becomes positive again, the op - amp has to get out of the saturated state before positive amplification can take place again . This change generates some ringing and takes some time, greatly reducing the frequency response of the circuit . </P> <P> An alternative version is given on the right . </P>

Precision full wave rectifier using op amp 741