Dynamic Measurement of Synthesizer Noise Spurs or Phase Noise

A technology of frequency synthesizer and phase noise, applied in noise figure or signal-to-noise ratio measurement, automatic control of power, measurement device, etc., can solve problems such as unreliable radar measurement

Active Publication Date: 2020-09-22
TEXAS INSTR INC
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Problems solved by technology

Therefore, high phase noise or spurs can render radar measurements unreliable

Method used

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  • Dynamic Measurement of Synthesizer Noise Spurs or Phase Noise
  • Dynamic Measurement of Synthesizer Noise Spurs or Phase Noise
  • Dynamic Measurement of Synthesizer Noise Spurs or Phase Noise

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no. 1 example

[0038] This process is illustrated for the first embodiment using the equations or process steps described below:

[0039] a. Let x[n] be the digital samples output by the ADC of the PN measurement circuitry. Take N such consecutive samples. Thus, x[n], where n=0 to N-1, can be used as a block sequence of numbers in the processor's memory.

[0040] b. Perform FFT on x[n] to obtain FFT result X[k], where k=0 to N-1.

[0041] c. Find the signal Y[k]=X[k]*X[k], where the operation ".*" means element-wise multiplication. For example, Y[0]=X[0]*X[0], where "*" means multiplication. In other embodiments, Y[k]=|X[k]| may be found to have equivalent PN measurement performance. Here, |X[k}]| denotes the absolute value of the sequence X[k], and the meaning of "absolute value" is well known to mathematicians and engineers.

[0042] d. Optionally, repeat steps a, b, c more (eg L) times (iteration i=1 to L). The digital samples are different for each acquisition because new acquisiti...

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Abstract

In the described example of the method (100) of measuring phase noise (PN), the PLL frequency synthesizer comprises a first phase frequency detector (PFD) receiving (101) a reference frequency signal, the first phase frequency detector ( PFD) is coupled to a first charge pump (CP) coupled to a VCO having an output fed back to the first PFD through a feedback divider that provides a divided signal to the first PFD. The first PFD outputs an error signal. The PN measurement circuitry includes a replica CP coupled to the output of the second PFD or the first PFD. The error signal is received at the replica CP, or the frequency-divided signal and the reference frequency signal are received at the second PFD. The replica CP outputs a scaled phase error current, which is current-voltage converted and amplified (102) to provide an amplified phase error voltage, and digitized (103) to provide a digital phase error signal. Frequency analysis (104) is performed on the digital phase error signal to generate a PN measurement.

Description

technical field [0001] This application is concerned with the dynamic measurement of noise spurs or phase noise generated by frequency synthesizers. Background technique [0002] A frequency synthesizer includes an electronic system that generates (one or more) higher frequency signals at its output from lower frequency signals received from a single fixed time base or master oscillator. A common way to implement a frequency synthesizer is to use a phase-locked loop (PLL). [0003] A PLL is a feedback control system that includes an error detector (including a phase-frequency detector coupled to a charge pump) that compares the phases of two input signals (a reference frequency signal and a divided, higher frequency output signal) compared to produce an error signal proportional to the difference between their phases. This error signal is then low pass filtered and used to drive a voltage controlled oscillator (VCO), which produces a higher output frequency. This output f...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R29/06G01S13/931
CPCG01S7/03G01S7/4008G01S7/4017G01S13/343G01S13/345G01S13/931G01R29/26H03L7/06
Inventor K·苏布拉吉S·斯玛拉R·加内桑
Owner TEXAS INSTR INC
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