Hi Brian --
It's good to collect this data; thanks. It's interesting that your std
dev in the first test seems to increase significantly with the number of
samples; I haven't seen that kind of scaling here (1K sample and 10k
sample turned in very similar std dev). From what Poul-Henning said
Brian
The 5370B has inadequate resolution and noise to allow detection of the
difference between a jitter of say 1ps or one 4x that.
Your longer term measurements probably reflect the combined effect of
thermal drift in the 5370B and thermal drift in the divider propagation
delay.
The acceptable
John
One can cure the propagation delay tempco associated with a 74HC390
divider string by resynchronising the output to the input clock.
However worst case design means that a 3 stage synchroniser is required.
Assuming a 10Mhz input clock frequency:
First resychronise the output to 1MHz (worst
John
With a slow slew rate input signal like a 10MHz sinewave the Wavecrest
jitter due to the noise of its wideband input amplifiers may be quite high.
So it may be better to measure the relative jitter of 2 dividers.
Bruce
John Ackermann N8UR wrote:
Hi Brian --
It's good to collect this
I can do that, but was hoping to isolate the performance of the Wenzel
waveform conversion circuit. An initial test showed jitter of about 25
ps -- which is about the same as for the whole divider chain, so you may
be correct that the input amplifiers are limiting. But also, I was
doing a
I believe having STD in parts of 10-14th is fairly respectable for
amateur designs..
It depends on whether it's due to the counter or the DUT. Keep in mind the
5370's own jitter is about 15-20 ps for a best-case unit (and they all seem
to be a bit different).
For an application like an ADC
John
The jitter of the Wenzel waveform conversion circuit will vary with the
input signal amplitude.
Thus one could probably measure the jitter as a function of input signal
amplitude and derive the waveform conversion circuit jitter performance
from that data.
Bruce
John Ackermann N8UR wrote:
John
I can't find a spec for the Wavecrest 2075 input amplifier/trigger
circuit noise but it could be as high as 1mV rms given its 800MHz+ input
bandwidth.
If the noise is 1mV rms:
Then an input signal slew rate of 1V/ns is required to keep the jitter
contribution of the amplifier input noise
Bruce Griffiths said the following on 04/04/2009 07:30 PM:
John
I can't find a spec for the Wavecrest 2075 input amplifier/trigger
circuit noise but it could be as high as 1mV rms given its 800MHz+ input
bandwidth.
If the noise is 1mV rms:
Then an input signal slew rate of 1V/ns is
John
The parameters for a simple model for the Wavecrest input jitter can be
derived from your measurements as
For each channel:
Jitter = SQRT[8E-24 + 2.53E-7/(S*S)]
Where S is the input signal slew rate at the trigger threshold
Input noise ~ 503 uV rms. (2.53E-7 = square of input rms noise)
Bruce,
Your analysis conforms closely to measured results on my DTS-2075.
With the cleanest 10MHz source I have, at 2Vp-p, the DTS-2075 jitter
reading is 11.4ps rms. Running this number back into equivalent input
noise yields 716uV rms. The DTS-2075 input spec (assumed to be
for -3dB response)
For start stop measurements with the same slew rate signal at each input
channel
Total jitter = SQRT [16E-24 + 5.06E-7/(S*S)]
where the effective (combined) input noise is 711 uV rms.
and the intrinsic jitter is 4ps rms.
Bruce
Bruce Griffiths wrote:
John
The parameters for a simple model
Hello Pete, Bruce,
I can confirm that the Wavecrest is sensitive to edge rise-time. It was not
designed to measure sine waves.
With a 10MHz sine wave from a Fury GPSDO as the source I get 8 - 10ps rms
jitter.
That exact same signal run through an NC7SZ04 buffer prior to feeding it
into
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