Two channel test instrument with active electronicphase shift means
First Claim
1. A two channel, a.c. test instrument comprising:
- a first signal channel for carrying a first test signal and including a first frequency converter for converting the first test signal to an intermediate frequency;
a second signal channel for carrying a second test signal and including a second frequency converter for phase coherently converting the second test signal to the same intermediate frequency;
measurement means for measuring the relative values of the converted first and second test signals; and
electronic phase shift means connected in series with the second signal channel between the second frequency converter and the measurement means for shifting the phase of the converted second test signal as a function of the frequency of the second test signal.
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Abstract
A network analyzer is provided with an electronically variable phase shifter in the IF portion of the reference channel, and the phase shifter is connected to sweeping signal generator (sweeper) driving the device under test. As the output frequency of the sweeper changes, the control signal to the phase shifter changes the phase shift in the IF portion of the reference channel, compensating for phase differences between the test and reference signals due to different line lengths in the two signal paths. The electronically variable phase shifter may comprise a linear phase shifter such as a phase lock loop along with a frequency mulitplier and down converter to multiply the phase shift produced by the phase shifter.
30 Citations
9 Claims
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1. A two channel, a.c. test instrument comprising:
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a first signal channel for carrying a first test signal and including a first frequency converter for converting the first test signal to an intermediate frequency; a second signal channel for carrying a second test signal and including a second frequency converter for phase coherently converting the second test signal to the same intermediate frequency; measurement means for measuring the relative values of the converted first and second test signals; and electronic phase shift means connected in series with the second signal channel between the second frequency converter and the measurement means for shifting the phase of the converted second test signal as a function of the frequency of the second test signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification