The following couple of circuit diagrams provide a glimpse of the configuration for making a precision rectifier and direct coupled power source circuits.
The precision rectifier, which is also recognized as a super diode, is actually a arrangement acquired with an operational amplifier so as to have a circuit act as if it were perfect diode and rectifier. This is advantageous for high-precision signal control.
The op-amp-based precision rectifier really should not be mistaken for the power MOSFET-based active rectification ideal diode.
A straightforward precision rectifier circuit
The fundamental circuit applying this type of characteristic is shown in the below diagrams. As soon as the input voltage is negative, there exists a negative voltage within the diode, therefore it operates as if it were open circuit, absolutely no current goes in the load, as well as the output voltage stays zero.
As soon as the input is positive, it is increased through the operational amplifier, which usually switches the diode on. Current moves in the load and, due to the feedback, the output voltage becomes comparable to the input voltage.
Typically the limit of the super diode is extremely in close proximity to zero, yet is just not zero. It equates to the actual limit of the diode, divided with the gain of the operational amplifier.
This fundamental setup carries a problem, therefore it is not frequently used. Once the input turns into (even a bit) negative, the operational amplifier switches to an open-loop mode, since you cannot find any feedback signal via the diode. For any standard operational amplifier having high open-loop gain, the output saturates. When the input subsequently gets positive once again, the op-amp needs to get free from the over loaded condition just before positive amplification could take place all over again. This particular switching creates some rapid oscilations and requires a while, tremendously minimizing the frequency response of the circuit.
Precision Rectifier, Direct Coupled Power, CMOS Power Booster Circuit Diagrams Explained
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