A precision Rectifier active circuit is analyzed in this video that examines how this op amp diode circuit is working and how to find its input-output Voltage Transfer Characteristics or VTC. For more examples see https://www.youtube.com/playlist?list=PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt
This active rectifying circuit is designed with two operational amplifiers and two diodes with negligible forward bias voltage. Both op amps are properly biased with negative feedbacks and hence virtual short is applicable to both op amps. The second op amp is wired as a buffer. Depending on the value of the input voltage, the first op amp is operating either as a buffer or as an inverting amplifier with superposition. For more examples see
Thanks for watching. For more op amp Diode Circuit Examples please watch https://www.youtube.com/watch?v=ENq39EesfPw&list=PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt&index=1