Inverting Zero Crossing Detector
In the inverting zero crossing detector the input voltage is applied at the negative terminal of the op-amp and reference voltage = 0 is applied at the positive node of the op-amp. In the inverting zero crossing detector output of the given circuit goes into negative saturation when the applied input voltage is positive and output goes to positive when input voltage is negative, the circuit diagram of inverting zero crossing detector is given below.
Circuit Diagram of Inverting Zero Crossing Detector
The figure given below represents the circuit diagram of Inverting Zero Crossing Detector. In this circuit we have used inverting op-amp. Here , the input voltage V1 is given in the inverting terminal of the op-amp and non-inverting terminal of op-amp is grounded. here we are also use Protection diode.
Protection diode: These are simple diode which is used to prevent the op-amp from the high input gain, because here we use direct input voltage.
Working of Inverting Zero Crossing Detector
As per definition it detects the point where the input signal is Zero because it’s reference voltage is 0. Before start the working of Zero Crossing Detector we have to let the output voltage is +V sat.
Now see the circuit to understand the working.
As per circuit reference voltage is 0 which is applied at the non-inverting terminal of op-amp which is compared with Vin which is applied at the Inverting terminal of op-amp.
Now when positive half of the sinusoidal wave appears at the input and op-amp comparator compares its peak level with the reference voltage.
Vo = V ref – Vi
because the reference voltage is 0, so
Vo = 0 – Vi
as we have already mentioned that starting output voltage is (+V sat), so
Vo = 0 – (+V sat)
Vo = (-V sat).
Now when the negative half of the sinusoidal wave appears at the input and op-amp compares its peak level with the reference voltage.
So,
Vo = V ref – Vi
Vo = 0 – (- V sat )
We get
Vo = (+V sat )
Here we can clearly see that how a Inverting Zero Crossing Detector detects the changes in the level of applied input sinusoidal signal.
Input and Output Waveform
In the beginning we have already mentioned that Inverting Zero Crossing Detector is also known as a Square Wave generator. Same as the output of the Window Comparator is nothing but a Square Wave.
Now Let us see how a Zero Crossing Detector generate the Square Wave or Output waveform.
in the working part we have derived that Vo for the positive half of the sinusoidal signal is (-V sat). because of this we get negative output for the positive half of the applied signal. while Vo for the negative half of the applied input signal is (+V sat). because of this we get positive output for the negative half of the applied signal.
So after observation of output waveform of Inverting Zero Crossing Detector we can say that output is reflection of applied input sinusoidal signal.
Zero Crossing Detector
A voltage comparator circuit whose output changes concerning the input signal which is crossing the zero of the reference voltage level that’s why it is called a Zero Crossing Detector. These circuits are commonly known as switching circuits the output of these circuits lies between positive and negative saturation voltage levels. The most commonly used circuits are the Schmitt trigger, Astable, and Monostable Multivibrators.
Table of Content
- What is a Zero Crossing Detector?
- Types
- Inverting Zero Crossing Detector
- Non-Inverting Zero Crossing Detector
- Applications
- Advantages and Disadvantages
- Comparsion Between Comparator and Schmitt Trigger