05 September 2007

Comb generator, preliminary

This is a preliminary circuit diagram of a comb generator using a 74HC00/74AC00:

The first gate is biased as a XTAL oscillator. I picked 10 MHz but any HF junkbox rock will probably do. Pretty standard stuff.

The second gate is a simple buffer for the oscillator output. Makes sense.

The third gate delays the signal of few nanoseconds, enough to produce -hopefully- a glitch in the 4th gate output. Will it work?

The R-R-R network is a simple ~10dB ~50ohm attenuator pad to match the impedance to 50 ohm loads (D.U.T. - Devices Under Test - mainly HF/VHF filters in my case).

According to my paperwork the comb peaks should be separated of half the XTAL frequency.

I've always wanted to put to a good use TTL gates propagation delay! Let's see...