How to generate constant amplitude RF signal usign variable amplitude RF signal
I need to generate synchronization signal from incomig RF sine wave signal. The incoming signal varies from +10 dBm to -15 dBm, frequency is stable in 50 - 100 MHz range.
What would be optimal circuit to do it?
Andrey
You can use a VGA (Variable Controlled Amplifier) controlled by an AGC circuit (Automatic Gain Control).
If your sync level can be lower than -15dBm, you can use a variable PIN-diode attenuator controlled by an AGC circuit.
Thank you for your reply vfone. Intersting ...
I wonder if there could it be simpler way of doing it?
If it would be analog signal I would attempt to clamp it with two Zener diodes, then amplify.
Can similar strategy be implemented in RF domain?
When it is stable and has sufficient S/N ratio when filtered with a 50...100 MHz wide filter, you may put it (after filtering) into a clipping circuit. If phase must be stable under varying input signal, you should use a non-voltage-saturating circuit (ECL like circuitry?). The reason for this is that propagation delay will depend on drive level.
Similar circuits you see in the IF limiting/RSSI stage in integrated FM receivers.
Analog devices makes ICs specifically RF clock recovery and phase detection. Look up the AD8309, it uses log amps with a limiter on the output. The limited output is a square wave, so you might have to filter it if you want a sine wave back.
Thnk you for kind advices.
Andrey