Simple AM op amp modulator

320

06:07:24

A high frequency op amp would be required for ranges 1MHz and higher

published 2 years ago

592azy2circuitdude

2 years ago

Say, this is very interesting. Are you sure high-frequency opamps exist? I've never heard of any, but if they did, that'd sure be neat. Also, do you think the drain and source terminals should be reversed? I don't know if that makes any difference, though.

joshinator

2 years ago

High frequency probably isn't the best terminology, but I'm fairly sure that there are general purpose op amps that have a higher dropout frequency than UA or LM series chips at 1MHz. I believe the TL series reaches 3MHz or a little higher.

joshinator

2 years ago

As far as the mosfet... I'm not actually sure! When using nMOS for amplification, I conventionally get the output from the drain side. But thats when I'm amplifying the signal voltage at the gate.The sim doesn't seem to care, but I'll have to test it out when I get the chance to make a practical circuit

592azy2circuitdude

2 years ago

The MOSFET here is in the Triode/Ohmic region. So it is behaving more like a voltage dependant resistor. I think this is good because in an inverting opamp circuit, the gain is determined by the ratio of the resistors. Also, there is no body diode in EC MOSFETs, which, I imagine, would explain why the drain and source can be reversed

joshinator

2 years ago

That makes sense! And definitely helps with my understanding of MOSFETs

eekee

2 years ago

this is what i use when i want a quick am signal source in simulation.

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