Perhaps I should mention that we are trying to qualify a new oscillator chip which we have designed. The foundry we used is a specialist at oscillator design and testing, and they have reported noticing the chirp in their test facility. Their test system is general purpose and so has different conditions to the finished product.
Hence we need to check their measurements on the finished product, which is a small ceramic TCXO, where we have bonded-out die and the correct crystals. There are no capacitors, except for the compensation system provided on the silicon. To make matters worse, we have to look at this problem throughout the operating temperature range, -40 to +85 deg C. Since we are intending to supply these parts to existing customers, it's not practical to suggest to them that they do anything different to what they did with previous compatible products. It is likely we don't have a problem in practice, but without measuring, we won't know. Indeed, do we have a chirp start problem with existing products? Essentially we've discovered a hole in our measurement capability, and it's enmbarrassing that the foundry can measure the problem (we believe they use a fancy Agilent Phase Noise system and post process the data) and we can't! 73, Murray Greenman ZL1BPU _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
