low phase shift limiter: SL532

That's a single-stage 300MHz bandwidth amplifier meant for use as a limter stage at IF frequencies to 60MHz, etc. In the late 60s and early 70s there were lots of IF-strip limiter ICs available, but they were multi-stage (rather than single-stage like the SL532), as is needed for proper FM signal performance, etc. Nowadays the multistage limiters come embedded in ICs with other receiver parts, and not so often by themselves.

Are you trying to repair something old, or create a new design?

I need to detect the phase shift between two signals. I like the features of the AD9901 phase/frequency discriminator, because when the phase difference exceeds the useful range, the sign of the error remains correct, so I can make a servo system that keeps the phase difference at the middle of the useful range. I don't want amplitude variations on either input signal to be interpreted as phase variations.

I thought the AD9901 had its VCO and REF inputs very similar to that of the SL532 (differential pair). I made tests with the AD9901 alone. When I vary the amplitude of one input by say, 3dB, the AD9901 reacts as if this was about

5-degree phase change (undocumented in the AD9901 datasheet). A pair of SL532's would improve things. There arnt't either many competitors for the AD9901.

Jean-Pierre Coulon

Oh, so you just want a high-bandwidth limiter. There are many suitable ICs -- would you like some help in finding one? What are your parameters of interest?

10 MHz. about 0dBm. 3 dB change must cause less than 1 degree of phase shift.

Jean-Pierre Coulon

And your power supply constraints?

Well, like a good old opamp, say 10 mA, either with +/-15 or +/-5 supplies.

Jean-Pierre Coulon