Atec Agilent-N5227A - Manual (Page 32)

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Table 25. Group Delay - Typical
Group delay is computed by measuring the phase change within a specified frequency step (determined by the
frequency span and the number of points per sweep). In general, the following formula can be used to determine the
accuracy, in seconds, of specific group delay measurement:
±Phase Accuracy (deg)/[360 × Aperture (Hz)]
Depending on the aperture and device length, the phase accuracy used is either incremental phase accuracy or worst-
case phase accuracy
Description Typical Performance
Aperture (selectable) (frequency span)/(number of points -1)
Maximum Aperture 20% of frequency span
Range 0.5 x (1/minimum aperture)
Maximum Delay Limited to measuring no more than 180° of phase change within the
minimum aperture.)
The following graph shows characteristic group delay accuracy with full 2-port calibration and a 10 Hz IF bandwidth.
Insertion loss is assumed to be < 2 dB and electrical length to be ten meters.
For any S
ij
Group Delay measurement, S
ii
= 0, S
ij
= 1, S
ji
= 0, S
kl
= 0 for all kl ij