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AssigneeHarris Corporation
InventorsEsteban G. Najle, Robert M. Buckley
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An improved circuit for phase noise measurements utilizing a frequency down conversion/multiplier and direct spectrum measurement technique which uses a combination of a phase detector method and a direct spectrum approach. The circuit is particularly useful for field test environments where laboratory instrumentation is normally not available, and fast and accurate phase noise measurements are required. The phase noise measuring circuit includes a frequency mixer which has a first input signal from a device under test and a second input signal from a reference stable oscillator having ultra low phase noise with a fixed center frequency. The frequency mixer mixes the first and second input signals to produce a down converted signal comprising the frequency difference signal of the first and second input signals. A lowpass filter then passes the down converted signal to a frequency doubler circuit which produces a doubled frequency, down converted signal. A lowpass signal filter then passes the doubled frequency, down converted signal to an amplifier. The output of the amplifier is directed to a second frequency doubler circuit which produces a quadrupled frequency, down converted signal. That signal is then directed to a further lowpass filter which passes the quadrupled frequency, down converted signal to a further amplifier. Finally, a direct approach spectrum analyzer analyzes the amplifier output signal which is an intermediate frequency signal in the most sensitive range of the spectrum analyzer for phase noise measurements on the device under test.
A phase noise measuring circuit for measuring the phase noise of a device under test, comprising:
A phase noise measuring circuit for measuring the phase noise of a device under test, consisting essentially of:
A phase noise measuring circuit for measuring the phase noise of a device under test, comprising:
A phase noise measuring circuit for measuring the phase noise of a device under test, consisting essentially of:
A phase noise measuring circuit for measuring the phase noise of a device under test as claimed 13, wherein the second input signal from said reference stable oscillator has a phase noise which is less than the phase noise of the device under test by at least 10 dB.
A phase noise measuring circuit for measuring the phase noise of a device under test as claimed 12, wherein the second input signal from said reference stable oscillator has a phase noise which is less than the phase noise of the device under test by at least 10 dB.
A phase noise measuring circuit for measuring the phase noise of a device under test as claimed 2, wherein the second input signal from said reference stable oscillator has a phase noise which is less than the phase noise of the device under test by at least 10 dB.
A phase noise measuring circuit for measuring the phase noise of a device under test as claimed 18, wherein the second input signal from said reference stable oscillator has a phase noise which is less than the phase noise of the device under test by at least 10 dB.
Dependencies are inferred from the claim text.