Dr Bruce Griffiths said the following on 02/02/2007 06:29 PM: > Since the MAX477 has an input noise of around 5nV/rtHz at 10MHz compared > to around 1nV/rtHz for a low noise bipolar transistor, the MAX477 may be > expected to be have a phase noise floor of up to 14dB higher than that > of an optimised discrete transistor amplifier. This however may not be a > concern unless one has an OCXO with a phase noise floor approaching the > state of the art (-180dBc/Hz).
I had a chance to measure a TADD-1 using an HP-3048 phase noise system last year. I've attached a screen shot of the results; in short it was below -140dBc/Hz from 100 Hz on out (by the way, I'm not sure I would trust the noise floor shown in this test; I am not certain we had the best test set-up). That's within a few dB of what HP said their 5087A amplifier would do. I'll soon have access to a new phase noise measurement system and will relook at the TADD-1 performance with it. John
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