Signature Panel -
The Signature Panel is accessed by clicking the 4th tab. In this panel you can adjust and save settings to optimize the waveform output at various clock frequencies.
When operating the AWG at different clock frequencies, the settings may need to be changed for optimal performance, especially at higher clock speeds, when the timing and thresholds of data samples are less forgiving and need to be adjusted for different clock frequencies. We have already provided you with a signature file in the main AWG directory. The signature file contains preset signatures for frequencies from 500 MHz to 2.5 GHz. When using the AWG, you might need to fine tune the preset signatures, and you can record your changes.
Clock Frequency
Slide the Clock Frequency bar to match the frequency of your clock source. If settings had previously been stored for this frequency (or a lower frequency) in the signature file, the settings will be recalled.
Even if you set the clock frequency in the Module Parameter panel, you must set
it again on this signature panel, although if you set it here, the Module Parameter
panel will reflect this setting. It is recommended to set the clock frequency within
the range of 500 MHz to 2.5GHz.
SEL
Selects between four possible times to sample the data. At least one SEL setting allows data to be sampled near the most open part of the eye between signal switching.
VREF
Sets the reference voltage, which is a threshold for binary data. Typically the lower end works better, but setting VREF too low may result in data loss.
DATAN
Sets an average voltage for the data. This control does not affect anything significantly, although adjusting it may provide slight performance improvements at higher clock frequencies.
ATE
Toggles between using the falling edge and using the rising edge to sample the address. Often one setting will be superior to the other for several waveforms at a given frequency, although a few waveforms may require the opposite setting.
ATE can also be toggled from the Memory Control section of the Module Parameter panel.
Record Signature
When you have adjusted the settings optimally for your current clock frequency, click on the Record Signature button to save these settings. These settings will overwrite any previously saved settings for your selected frequency. The signature file must be in your working directory so that, in the future, these settings will be recalled whenever you slide the clock frequency bar to this frequency (or to a higher frequency, up to the next recorded signature).