Transceiver Phase Interpolator Self-Measurement for PI Nonlinearity
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Solution Overview
Problem
Existing methods for measuring phase interpolator (PI) non-linearity in transceivers are impractical for production environments as they require external high-speed scopes and cannot be performed on a per-transceiver basis, limiting precision due to silicon impairments and varying non-linear phase distributions.
Innovation Solution
A self-measurement technique using a test circuit within a transceiver that applies phase shifts to the clock signals and determines phase distribution based on changes in the bit pattern over time, allowing for per-transceiver analysis without external tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external high-speed scope is used to measure phase distribution, then measurement precision is improved, but device complexity and ease of manufacture deteriorate due to requiring external laboratory equipment
Solution Approach 1:
The transceiver performs self-measurement of its own phase interpolator characteristics using internal circuitry. The test circuit is integrated within the transceiver and uses the transceiver's own transmitter, receiver, and PI components to measure and characterize the phase distribution without requiring external measurement equipment.
Solution Approach 2:
The measurement function is merged with the transceiver's operational functions. The test circuit combines the transmitter, receiver, and phase interpolator into a single integrated measurement system, eliminating the need for separate external measurement equipment while maintaining measurement precision.
2Measurement precision
If external high-speed scope is used for measurement, then measurement precision is improved, but productivity deteriorates due to laboratory-only testing
Solution Approach 1:
The transceiver autonomously measures its own phase characteristics, enabling production-level testing without external laboratory equipment. This self-measurement capability allows rapid characterization of each transceiver unit during manufacturing, significantly improving production throughput while maintaining precision.
3Manufacturing precision
If per-transceiver phase distribution measurement is implemented, then manufacturing precision is improved, but ease of manufacture deteriorates due to requiring additional test circuitry
Solution Approach 1:
The test circuit is merged with the functional components of the transceiver. The phase interpolator used in normal operation is the same one being measured, and the transmitter/receiver pairs are integrated into a single testable unit, reducing the need for additional discrete test components.
Data Source
AI summary
An example circuit includes: a transmitter configured to transmit a clock pattern based on a transmit clock; a receiver, coupled to the transmitter, configured to sample the clock pattern based on a receive clock to generate a bit pattern, where there is a non-zero frequency difference between the transmit clock and the receive clock; a phase interpolator (PI) configured to add a phase shift to a source clock to supply one of the transmit clock or the receive clock; and a test circuit configured to apply adjustments to the phase shift over a time period and determine a phase distribution of the PI based on changes in the bit pattern over the time period.