Phase Interpolator Self-Test Circuit for Linearity Characterization
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Solution Overview
Problem
Existing test equipment for characterizing phase linearity in communications devices is expensive, inaccurate, and time-consuming, particularly when testing over a wide range of phase steps, which can lead to increased bit-error-rate (BER) due to nonlinearities in phase interpolators.
Innovation Solution
A self-test circuit integrated within an integrated circuit, comprising a phase detector, phase-difference-to-voltage converter, analog-to-digital converter, and control logic, which generates a metric for phase linearity by comparing expected and measured outputs across a predefined range of phases, allowing for faster, cheaper, and more accurate characterization of phase interpolators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated external test equipment is used to characterize phase linearity, then measurement capability is provided, but cost increases and testing becomes time-consuming
Solution Approach 1:
The patent implements a self-test circuit integrated within the phase interpolator device that enables the device to test itself for phase linearity. The self-test circuit includes a phase detector, counter, and control logic that automatically measure phase linearity across multiple phase steps without requiring external test equipment, thereby eliminating time-consuming external testing while maintaining measurement capability
Solution Approach 2:
The patent combines the test circuit functionality with the phase interpolator device by integrating a phase detector, counter, and control logic directly into the device. This merging of test and operational functions into a single integrated circuit eliminates the need for separate external test equipment and enables simultaneous or integrated testing during normal operation
2Measurement precision
If dedicated external test equipment is used to characterize phase linearity, then measurement capability is provided, but cost increases
Solution Approach 1:
The self-test circuit enables the phase interpolator device to perform its own characterization, eliminating the need for expensive external test equipment. By using internal resources (phase detector, counter, control logic already present in the device), the patent achieves phase linearity measurement capability without additional manufacturing costs for external testing equipment
Solution Approach 2:
The phase detector and control logic in the self-test circuit serve multiple functions: they are used both for normal phase interpolation operation and for phase linearity testing. This multi-functionality eliminates the need for dedicated external test equipment, reducing manufacturing costs while maintaining measurement precision
3Measurement precision
If phase linearity testing is performed over a wide range of phase steps, then comprehensive characterization is achieved, but testing time increases
Solution Approach 1:
The self-test circuit performs phase linearity measurements continuously across all phase steps without interruption. The control logic automatically sequences through each phase step, accumulating measurement data in real-time, which enables comprehensive characterization of phase linearity over the full range while maintaining high testing speed and productivity
Solution Approach 2:
The self-test circuit is pre-configured within the device with all necessary components (phase detector, counter, control logic) ready to perform measurements immediately. This preliminary integration eliminates setup time and enables rapid sequential testing across all phase steps, achieving comprehensive characterization without time delays
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The self-test circuit enables faster, lower-cost, and more accurate determination of phase linearity, reducing errors and improving communication device performance by identifying nonlinearities and ensuring acceptable bit-error-rate (BER) across a wide range of phase steps.
Implementation Method 1
The phase detector is to generate an output that is proportional to a phase difference between the reference signal and the interpolator output
Implementation Method 2
The phase-difference-to-voltage converter is to convert the output from the phase detector into a corresponding voltage
Data Source
AI summary
A circuit includes a phase interpolator and a self test circuit. The phase interpolator is to provide a interpolator output having a phase corresponding to a respective phase step in a plurality of phase steps. The interpolator output is a weighted combination of one or more of a plurality of phasor signals. The self test circuit includes a phase detector coupled to a reference signal and the interpolator output, a phase-difference-to-voltage converter coupled to the phase detector, an analog-to-digital converter (ADC) coupled to the phase-difference-to-voltage converter, and control logic. The phase detector is to generate an output that is proportional to a phase difference between the reference signal and the interpolator output. The phase-difference-to-voltage converter is to convert the output from the phase detector into a corresponding voltage. The ADC is to convert an output from the phase-difference-to-voltage converter into a corresponding digital value. The control logic is to test the phase interpolator using the self-test circuit.