AWG G3 PAD FOR PS3 Specifikace stáhnout pdf (Strana 217)

Sampler 7 Analog Modules

System Reference, January 2001

217

In the sampler, the sampling period (T) is slightly different

(∆t) from a multiple of the signal period (t), that is,

T=nt+∆t. (∆t is called the equivalent sampling period.)

This under-sampling technique is called Coherent

Sampling. The sampling is performed for each of the spec-

ified phase points on the measured signal, then repeated

and averaged for each phase point.

To obtain a very short equivalent sampling period (∆t), the

sampling period (T) must be freely set. In this case, the

coherent sampling should use two master clocks. Two

master clocks are used, one for both the DUT (input signal

to sampler) and the synchronization trigger to the sampler

and one for the sampling clock of the sampler.

The shortest equivalent sampling period for using two

master clocks is 1 ps.

The following figure illustrates coherent sampling with

two master clocks:

Figure97 Coherent Sampling

t t

nt + t (n =2)

smp_ov

Phase Lock

Master Clock of

Digital Clock Domain

Master Clock of

Analog Clock Domain

I/O Channel Board

Sampler

DUT

Clock

Analog Out

Synchronization

Trigger

Sample

I/O Channel Board

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AWG G3 PAD FOR PS3 Specifikace Strana 217