HP 8753E manual Amplitude and Phase Tracking, Phase Linearity and Group Delay

Amplitude and Phase Tracking

The match between mixers is defined as the absolute difference in amplitude and/or phase response over a specified frequency range. The tracking between mixers is essentially how well the devices are matched over a specified interval. This interval may be a frequency interval or a temperature interval, or a combination of both.

You can make tracking measurements by ratioing the responses of two mixer conversion loss measurements. Then any difference you view in response is due to the mixers and not the measurement system.

Replace mixer A with the mixer that you want to compare it to. Mixer R should always remain in place as the reference mixer.

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NETWORK ANALYZER

PORT 1 1

1 0 dB -4/v%-

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R E F E R E N C E

M I X E R

1 P O R T 2

LOW PASS

C A L I B R A T I O N

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1 0 dB

C O N V E R T E R

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Figure 6-98.

Connections for an Amplitude and Phase Tracking Measurement Between Two Mixers

Phase Linearity and Group Delay

Group delay is the rate of change of phase through a device with respect to frequency (d+/dw). Traditionally, group delay has been used to describe the propagation delay (Tg), and deviation from linear phase through a linear device. However, this parameter also contains valuable information about transmission delay and distortion through a non-linear device such as a mixer or frequency converter. For example, flat group delay corresponds to low modulation distortion (that is, carrier and sidebands propagate at the same rate).

Phase linearity and group delay are both measurements of the distortion of a transmitted signal. Roth measure the non-linearity of a device’s phase response with respect to frequency.

Application and Operation Concepts 6-167