Frequency Domain PSRR Measurement Using Multi-Tone Signals
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Solution Overview
Problem
Existing methods for measuring power supply rejection ratio (PSRR) are limited by the dynamic range of oscilloscopes, which cannot accurately measure PSRR values exceeding 50 decibels, and are prone to noise and frequency multiplication issues in time-domain measurements.
Innovation Solution
A testing method and system that utilize a signal generator to transmit a multi-tone signal to an under-test device, and a spectrum analyzer to measure input and output ripple intensities across multiple frequencies, allowing for the calculation of PSRR ratios in the frequency domain, thereby overcoming the limitations of time-domain measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oscilloscope is used to measure power supply rejection ratio in the time domain, then the measurement can be performed, but the measurement range is limited to 40-50 decibels due to the oscilloscope's voltage measurement capability
Solution Approach 1:
The patent replaces the time-domain measurement approach with a frequency-domain measurement approach. Specifically, it substitutes the oscilloscope-based time-domain measurement system with a signal generator and spectrum analyzer-based frequency-domain measurement system, enabling accurate measurement of power supply rejection ratio beyond the oscilloscope's limited dynamic range
Solution Approach 2:
The patent changes the measurement parameter domain from time domain to frequency domain. By measuring input and output ripple intensities at multiple frequencies and calculating power supply rejection ratio in the frequency domain, the system overcomes the oscilloscope's dynamic range limitation and achieves accurate measurement for higher PSRR values
2Device complexity
If time-domain measurement is used, then the measurement process is simple, but the dynamic range of measurement is limited
Solution Approach 1:
The patent replaces the simple time-domain measurement system with a more complex but capable frequency-domain measurement system consisting of a signal generator, spectrum analyzer, and control device. This substitution enables extended dynamic range measurement capability while maintaining systematic operation through automated control
3Measurement precision
If frequency-domain measurement is used, then the dynamic range is improved, but the measurement process becomes more complex
Solution Approach 1:
The patent employs a control device that coordinates multiple instruments (signal generator and spectrum analyzer) to perform the measurement process. The control device generates multi-tone signals with specific frequency components, controls the spectrum analyzer to measure input and output ripple intensities, and automatically calculates power supply rejection ratio, thereby managing the complexity through integrated multi-functional control
Solution Approach 2:
The measurement system performs self-characterization by automatically generating test signals, measuring responses, and calculating results without requiring manual intervention. The control device autonomously manages the entire measurement process, including signal generation, data acquisition, and computation of power supply rejection ratio across multiple frequencies
Data Source
AI summary
An testing method includes following operations: generating, by a signal generator, a multi-tone signal; transmitting, by the signal generator, the multi-tone signal to an input terminal of an under-test device; measuring, by a spectrum analyzer, the input terminal of the under-test device and an output terminal of the under-test device to acquire a plurality of input ripple intensities corresponding to a plurality of frequencies and acquire a plurality of output ripple intensities corresponding to the frequencies; and generating, by a control device, a plurality of power supply rejection ratios corresponding to the frequencies according to the input ripple intensities and the output ripple intensities.