Hello,
I bought an H-Bridge IC called "ZXMHC 6A07", here is the datasheet.
I connected the source (S1,S4) to +3.3V to an external lab power supply. The other pair of source pins (S2,S3) are connected to gound. The gates on the "left hand side" (G1,G2) are connected to a roughly 25 kHz 3.3Vpp (1.65V offset) square wave. And G3,G4 are connected to the same, but inverted signal (25 kHz 3.3Vpp 1.65V offset, square, 180 degrees phase difference). Also both gate sides are pulled down with a 10k resistor to ground.
Right, now I have a 6.6Vpp signal. Everything as I expect it so far.
Now I connect a roughly 20 ohm resistor across the drains (D1,D2 and D3,D4) and read the differential voltage across that resistor. I connect both ground clips of my probe together and measure at both drains. I get a slight attenuation because of the internal resistance of the H-Bridge, but the signal stays at around 6Vpp.
Now I want to connect the same drains to an RLC series resonant circuit. I use an inductor with about 1.46 mH, and a capacitor with a value of 25.5nF. That would make a resonance frequency of about 26kHz. So I set my signal generator to 26kHz and connect everything in series. I expect the LC part to behave as a almost short circuit, and the 6Vpp across my 20 ohm resistor. But to my surprise I measured it to be 3.2Vpp.
After that I played a bit with the frequency, but it didn't get better. I could only get 3.2Vpp across the resistor. I double and tripple checked the inductor and capacitor values, but couldn't find the problem. What's going on here ?
Edit: I attached an image to clarify the question. In that image, R1 is the load I try to replace with a series RLC circuit.
I bought an H-Bridge IC called "ZXMHC 6A07", here is the datasheet.
I connected the source (S1,S4) to +3.3V to an external lab power supply. The other pair of source pins (S2,S3) are connected to gound. The gates on the "left hand side" (G1,G2) are connected to a roughly 25 kHz 3.3Vpp (1.65V offset) square wave. And G3,G4 are connected to the same, but inverted signal (25 kHz 3.3Vpp 1.65V offset, square, 180 degrees phase difference). Also both gate sides are pulled down with a 10k resistor to ground.
Right, now I have a 6.6Vpp signal. Everything as I expect it so far.
Now I connect a roughly 20 ohm resistor across the drains (D1,D2 and D3,D4) and read the differential voltage across that resistor. I connect both ground clips of my probe together and measure at both drains. I get a slight attenuation because of the internal resistance of the H-Bridge, but the signal stays at around 6Vpp.
Now I want to connect the same drains to an RLC series resonant circuit. I use an inductor with about 1.46 mH, and a capacitor with a value of 25.5nF. That would make a resonance frequency of about 26kHz. So I set my signal generator to 26kHz and connect everything in series. I expect the LC part to behave as a almost short circuit, and the 6Vpp across my 20 ohm resistor. But to my surprise I measured it to be 3.2Vpp.
After that I played a bit with the frequency, but it didn't get better. I could only get 3.2Vpp across the resistor. I double and tripple checked the inductor and capacitor values, but couldn't find the problem. What's going on here ?
Edit: I attached an image to clarify the question. In that image, R1 is the load I try to replace with a series RLC circuit.
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