Class D Amplifier is not Working ?

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Joined Dec 27, 2019
I am building a class D Amplifier,i have taken a reference of youtube channel of great Scott video link- (
) I have to build my circuit but, overall in the circuit, My hex inverter is not working. when I am providing a digital PWM signal from the LM393 comparator to the HEX inverter (MC74HC04AN), it should invert the PWM signal, but when I am performing,0 volts is coming in the second pin (output of hex inverter). when I powered the circuit, Mosfet driver Low input side input voltage is showing is zero.In the High input side,5 Volt is coming. but the low input side is not coming. I have changed my hex inverter but nothing has happened.
Operational Data:-
Is there any difference between MC74HC04A and SN74HC04?
Basic Testing of Hex inverter

I am posting another two pictures which are based on basic testing of Hex inverter. in this experiment, a)- first, I provided a square wave of 2.5 volts with 200 khz frequency, duty cycle 50% to the input of Hex inverter, and output was zero volts. b)- after 1st method was not worked properly, I just thought hex inverter will work as digital input 0 to 5 volt. that's why I provided the same data as above written with 2.5 volts dc offset extra to see the results. when I performed I got these results. please see the below pictures(figure 7, figure 8, figure 9 ).
# Class D Amplifier overall practical Data
  1. TLC 555 timer generates triangle wave Approx and above 200khz with 2.14 volt.
  2. LM3393 comparator using for comparing two signals, Audio signal( Sin wave - 1 Hz to 20 khz with voltage-2 volt(max)) and Triangular wave(2.14).(input voltage common-mode range reference taking consideration not more than 3.5 volts)
  3. Hex inverter((MC74HC04AN) is used for inverting the PWM signal.
  4. Ir2113 MOSFET driver is used for high-speed switching.
  5. IrlZ44 n MOSFETs are using.
I am posting my practical data which is shown in real-time operations (oscilliscope).
  1. Schematic Diagram of class D amplifier (Figure 1)
  2. Triangle wave (TLC555 Timer). (I am posting two pictures for clarity)(Figure 2, figure 6)
  3. LM393 comparator output (i am posting two pictures for clarity). (figure 3, 4)
Afterward, hex inverter is unable to work. the reason I don't know. please give me a valuable comment.


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