I am trying to develop a reliable 120 kHz ultrasonic transmitter circuit using the KEMET ND18X3N6 piezoelectric transducer.

Problem: Although the Arduino, TC4420, and IRF540N stages generate the required 120 kHz signal correctly, the waveform becomes weak and distorted when the PZT is connected, indicating an impedance/drive mismatch that needs to be resolved.

 

Hi parth,
Welcome to AAC.
Do you have a circuit diagram you could post?
E

 

Paraphrasing Rear Admiral Joshua Painter, "Engineers don't take a dump, son, without a schematic.".

ak

 

I am trying to develop a reliable 120 kHz ultrasonic transmitter circuit using the KEMET ND18X3N6 piezoelectric transducer.

Problem: Although the Arduino, TC4420, and IRF540N stages generate the required 120 kHz signal correctly, the waveform becomes weak and distorted when the PZT is connected, indicating an impedance/drive mismatch that needs to be resolved.

From what I know, the piezo transducer is strongly capacitive. If your drive circuit has some medium output impedance, without load it's perfect, but with load it will distort heavily.
But as others said, post the schematic with PNs.

 

another option
the pizo effisancy is at one particular frequency , with a very high Q.
these circuits often work with the pizo setting the frequency , for max output .
even if it say 120 Khz, it could be say 120.001 Hz ,