Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
What I meant is: are there any varicaps that can adjust theire capacity by milivolts of DC bias?
Well I have a signal of milivolts and want to detune a LC-circuit with such a varicap without amplifying the signal before. That's it.
So what amount we're talking about? Several nF? Because the datasheets I previously looked at, hadn't contained any mentions of Voltage in this magnitude.
Let's give you some theory and my practical experience.
- ALL diodes behave like are "varicaps" where diode capacitance is reduced from 0V bias to negative bias range in a log scale.
- However the tolerance is huge.
- The special diodes with process controls to tighten tolerances are called Varicaps.
- Diode capacitance increases with power ratings and conductor gap dimensions of the device, while ESR is inversely related to Pd max as size affects all 3 parameters.
- Typically diode Capacitance is measured in pF (not nF)
- Tuning range of 0 to 30V is common, or 0 to 5V with reduced range. ( NOT in mV ! .... you may be thinking of carrier detection)
But to resolve your query, first define your requirements in tuning range and accuracy. ( i.e. a design spec)
A VCXO is much more accurate and VCO chips are also more accurate and stable than a "DIY " VCO using LC parts as temperature stability and tolerances are much bigger.