deign frequency to voltage converter using analog ckt or ics

[anwersadique]

i want to convert the 3-5 mV and 4-10kHz frequency signal to voltage when frequency increases ,we want voltage incrases,,,but at the same time voltage may varies..so input voltage may not be constant

 

[BradtheRad]

Almost certainly you'll need to feed the pulses to an op amp. Configure it for open loop gain (maximum). The pulses will then be at fairly uniform voltage, at or near the supply voltage.

Then feed the pulses to a charge bucket circuit. Also known as a charge pump.

The pulses are conditioned to the same length. Pulses are applied to a capacitor. Its charge goes higher as the pulses come more rapidly. Its charge decreases as the pulses get slower.

Such a circuit could be built by you.

Or use a readymade IC specifically named 'frequency-to-voltage converter'.