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Takes an incoming 100MHz RF signal, mixes it with an LO of 90MHz, and outputs an amplified IF signal at 10MHz, derived from the difference between the RF & LO.
**Specs:
RF Input: 100MHz @ 20mV pp
LO Input: 90MHz @ 20mV pp
Output: 10MHz @ about 300mV pp
**Composition:
1 capacitive-based Mixer, 1 LC filter, 2 Buffers, and 3 stages of single-transistor RF Amplifiers.
**Design:
1. RF and LO are mixed via two capacitors, in series, output is taken from the center of the two caps.
2. Output of the mixer (made up of just 2 Capacitors) is Buffered
3. Output of 1st Buffer is sent to 1st Amplifier.
4. Output of 1st Amplifier is sent to the LC filter.
5. Output of the LC filter is sent to 2nd Buffer.
6. Output of 2nd Buffer is Amplified via two more stages, and that’s it!
I must say, filtering and extracting the IF frequency is the most challenging part of this whole design. But I did manage to achieve it through just a single parallel LC Band-pass filter, but it’s certainly not a wonderful solution by any means, and is in desperate need of improvement. Also, for those who are wondering, I decided to use such a high IF Frequency so it would be more visible in EveryCircuit… A lower difference frequency (IF) is certainly attainable and even easier to work with I’d assume as well, but is not so easily observable on this simulator due too such a high difference in the time division and scale of the oscilloscope between the the IF and RF/LO signals, which is why I chose 10MHz.
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