25 September 2007

Controlling canned oscillators

For a number of projects it might be interesting to control the frequency of a canned oscillator. Some of them have a control pin, others an enable pin, others... no option.

There are two possibilities, one of which should always work:
  1. controlling the voltage supply
  2. controlling the load capacitance
The latter works only if the module does not include an output buffer. Most recent canned oscillators should be insensitive to load C variations.

The voltage supply control apparently works on all canned oscillators. You'll need to map your oscillator behavior vs. voltage, but a few Hz shift can be achieved, say 200Hz at 30 MHz, that is 0.06%.