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Hi, I'm new to analog circuits. I have a simple question.
Can I use a 455khz ceramic/crystal resonator instead of LC tank on a quadrature demodulator input of MC3357?
Thanks.
Yes, but it has to be a ceramic resonator, not a filter. You will get lower distortion with a properly tuned LC filter though and the cost is similar. There are special ones made for this job and you may have to bridge it with a resistor or choke to keep the DC input at the demodulator happy.
Be careful, in the schematic it is there to provide phase shift in the demodulator but the ones shown are to set the frequency of an oscillator. It probably will work as long as you maintain a DC path to pin 8 of the IC but in general a ceramic resonator will recover far less audio and at higher distortion than an LC tuned circuit. Also bear in mind that ceramic resonators are not particularly accurate in regard to frequency, typically they can be +/- 5KHz from center frequency so you may lose some signal because it doesn't line up with the other filter.
If you do an internet search for "ceramic quadrature 455KHz" it will show some examples, including the expected amount of recovered audio when using different types and different ICs, including the MC3357.
Ceramic Resonator will not work for this particular application because the IC is supplied via LC Resonator Circuit.
Ceramic Resonator does not pass DC currents.
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