Spectral Leakage Loopback for Mixed-Signal Circuit Testing
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Solution Overview
Problem
Current methods for testing mixed-signal circuits, such as those in System on Chip (SoC), are costly and time-consuming due to the need for high-resolution analog-to-digital converters and automated test equipment, leading to increased production costs and long test times.
Innovation Solution
A spectral leakage-driven loopback method utilizing an on-chip Digital Signal Processor (DSP) to generate a digitally-synthesized single-tone sinusoidal stimulus, sample and measure signals through an analog loopback path, and perform postprocessing to predict harmonics, thereby reducing hardware measurement errors and achieving cost efficiency in predicting nonlinearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution ADC is used for circuit testing, then measurement precision is improved, but area overhead increases and power consumption increases
Solution Approach 1:
The patent uses a low-resolution ADC to capture spectral leakage information and reconstructs the equivalent response of a high-resolution ADC through digital signal processing. Instead of physically implementing a high-resolution ADC, the system creates a computational model that replicates its measurement capabilities, thereby achieving high measurement precision without the area overhead of actual high-resolution hardware
Solution Approach 2:
The patent replaces the physical high-resolution ADC hardware with a combination of low-resolution ADC and digital signal processing algorithms. The spectral leakage-based reconstruction method substitutes mechanical/electrical hardware complexity with computational complexity, achieving the same measurement precision through software-based signal processing rather than hardware-based high-resolution conversion
2Measurement precision
If high-resolution ADC is used for circuit testing, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The system creates a computational replica of high-resolution ADC functionality using low-resolution hardware and digital processing. This copying approach allows the system to achieve high measurement precision while consuming significantly less power than a true high-resolution ADC would require, as the low-resolution converter and subsequent digital reconstruction consume far less energy than high-resolution conversion hardware
Solution Approach 2:
The patent substitutes power-intensive high-resolution ADC hardware with a low-power combination of low-resolution ADC and digital signal processing. The spectral leakage reconstruction algorithm performs the heavy lifting computationally rather than electrically, dramatically reducing power consumption while maintaining measurement precision
3Measurement precision
If automated test equipment is used for production testing, then measurement precision is improved, but production testing cost increases and test time increases
Solution Approach 1:
The patent implements a built-in self-test (BIST) mechanism where the device under test performs its own characterization using an on-chip DSP core. The system generates test signals, captures spectral leakage through the loopback path, and reconstructs device responses autonomously without external test equipment. This self-service approach eliminates the need for expensive automated test equipment and significantly reduces test time while maintaining measurement precision
Solution Approach 2:
The system uses spectral leakage information to create a computational model that replicates the device's frequency response characteristics. By reconstructing the device response from leakage measurements rather than direct high-resolution sampling, the system achieves accurate characterization much faster than traditional swept-sine or network analyzer methods, thereby improving productivity without sacrificing measurement precision
Data Source
AI summary
A spectral leakage-driven loopback method for predicting performance of a mixed-signal circuit. The method includes generating, by an on-chip Digital Signal Processor (DSP) core, a digitally-synthesized single-tone sinusoidal stimulus. A nonlinear digital-to-analog-converter (DAC) channel is sampled. A DAC output signal is supplied to a nonlinear analog-to-digital converter (ADC) channel through an analog loopback path. Each of the DAC channel and the ADC channel are measured for a production testing. The on-chip DSP core performs postprocessing and predicting harmonics of the two individual DAC and ADC channels.