The use of Operational amplifiers can improve the performance of a wide variety of signal processing circuits. In rectifier circuits, the voltage drop that occurs with an ordinary semiconductor ...

Schemes of two-half-period rectifiers on op amps with switching inputs in accordance with the polarity of the input voltage are given. The switching of inputs is performed by a control signal taken ...

And here it is, modelled using LTSpice. It is the same circuit as the classic simple precision rectifier (set to pass the negative half-sine), but with the non-inverting input of the op-amp connected ...