[time-nuts] 74HC4046 receiver

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Apr 9 04:02:13 UTC 2009


Pete wrote:
> Bruce,
>
> The jitter measurements were made via the DTS PER function.
> This looks only at CH1 & the reference is the DTS internal
> 100MHz. OXCO. DTS-2075 jitter floor is < 3ps rms.
>
> The Fairchild & National parts have identical datasheets &
> spec SIGin sensitivity as 133mV @ Vcc=6V. The Philips
> version specs SIGin sensitivity as 35mV @ Vcc=6V.
>
> Fine idea to look at delta with 2ea 'AC04s driven from a
> common source; I'll try it in the next day. Unfortunately, I
> have no low jitter (<5ps) fast transition source to properly
> drive the parts. It's still worth a look.
>
> Pete 
>
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>   
Pete

When driving 2 AC04's from the same source and measuring the resultant
differential jitter, the input source jitter is relatively unimportant
particularly if the input signal risetime is transition times are
sufficiently low ( < 5ns??).
If all else fails and you can afford to wait long enough you could even
use the PPS output from a GPS receiver.

Driving both AC04's from a sinewave input and measuring the output
differential jitter with different amplitude inputs allows one to
estimate the noise from the measured output jitter and the known input
signal slew rates. Adjusting the dc level at the AC04 input for a 50%
output duty cycle is desirable to reduce the uncertainty in the
estimates of the input signal slew rate at the switching threshold.

Bruce



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