ATS9462 User Manual
41
Optional External Clock
ATS9462 PCI Digitizer optionally allows you to supply the
ADC clock. This option is extremely important in many RF
applications in which phase measurements must be made
between the inputs themselves or between the inputs and an
external event.
Driving high performance ADCs must be done carefully, as
any injection of phase jitter through ADC clocks will result in
reduction in data conversion quality.
Aside from phase noise, the clock signal for a pipelined ADC
must also have a duty cycle close to 50%. This maximizes
the dynamic performance of the ADC. See Fast External
Clock section below for more details.
External clock input impedance is fixed at 50 Ohms.
External clock input coupling can be set to AC or DC, under
software control.
There are three types of External Clock supported by
ATS9462:
•
Fast External Clock
•
Slow External Clock
•
10 MHz Clock Reference
The following paragraphs describe the three types of External
Clock input and outline the restrictions on each of them.
