SiT-AN6722EB Manual Rev. 2.0
Page 5 of 8
SiT6722EB Evaluation Board User Manual
3.3
Measuring Jitter and Phase Noise
For jitter measurements, make sure that SMA connector and source termination resistor R9 are properly
soldered on the EVB. R9 value should be 25Ω for best source matching (refer to SiTime
more information). The R9 can be populated using one of the following options:
1)
0Ω resistor. This allows DC coupling the output to 50Ω instruments directly. Note that due to
50Ω loading, the signal swing levels and rise/fall times will be different from those specified
in the datasheet.
2)
0.1uF capacitor for AC-coupling to 50Ω instruments.
SMA connector is used to connect directly to the jitter measurement instrument, such as Time Interval
Analyzer (TIA) or high-bandwidth real-time oscilloscope. Jitter measurement technique is described in
SiTime
The SMA can also be connected through 50Ω coaxial cable to signal source analyzers or spectrum
analyzers to measure phase noise. In such case the use of AC-coupling configuration is recommended
because not all measurement instruments can accept DC voltage at their inputs.
3.4
Current Measurement
To measure the current, remove zero-ohm resistor R4, and connect the DMM or other current
measuring device across this connector. It is recommended to measure the voltage on DUT VDD and
adjust for any drop on the DMM to ensure known VDD voltage on the device.
