PAM Receiver Jitter Calibration for Fast Threshold Setup
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Solution Overview
Problem
The existing receiving devices for pulse-amplitude modulation (PAM) data transmission require an enormous amount of time to calibrate threshold values to achieve a bit error rate (BER) of less than 10−12, as they need to demodulate a large number of symbols for each candidate threshold value, making the calibration process time-consuming.
Innovation Solution
The receiving device introduces jitter to the clock signal to intentionally degrade the eye diagram, allowing for a reduction in the number of symbols to be demodulated for each candidate threshold value, thereby shortening the calibration time by specifying the optimum threshold values based on the reduced eye diagram characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiving device uses conventional threshold calibration methods to ensure BER < 10^-12, then the bit error rate is sufficiently low for reliable communication, but the calibration time becomes excessively long
Solution Approach 1:
The patent applies partial action by intentionally adding jitter to the clock signal to degrade the eye diagram, which allows calibration to be performed with fewer symbols than would normally be required. This partial degradation enables faster calibration while still achieving sufficient reliability (BER < 10^-8) for practical communication systems, resolving the contradiction between calibration time and error rate performance
Solution Approach 2:
The patent changes the parameter of the clock signal by adding controlled jitter, which transforms the eye diagram characteristics. This parameter change allows the system to perform calibration with reduced eye diagram opening, enabling faster convergence to optimal threshold values while maintaining acceptable demodulation performance
2Measurement precision
If the receiving device demodulates a large number of symbols for each candidate threshold value, then the threshold calibration accuracy is high, but the computational complexity and processing time increase significantly
Solution Approach 1:
By intentionally degrading the eye diagram through jitter addition, the patent enables threshold calibration to converge with fewer symbol demodulations. The degraded eye diagram provides sufficient contrast to identify optimal thresholds without requiring the extensive symbol processing needed for high-precision calibration in ideal conditions, thus improving calibration speed while maintaining practical accuracy
Solution Approach 2:
The patent uses a simplified calibration approach that sacrifices some calibration precision (accepting BER < 10^-8 rather than 10^-12) to dramatically reduce the computational resources and time required. This disposable approach to ultra-high precision calibration allows the system to achieve sufficient performance much more efficiently
Data Source
AI summary
A receiving device includes first, second, and third circuits, and a processing circuit. The first circuit is configured to calculate a phase difference between a first clock signal and a data signal, which is a signal modulated by pulse-amplitude modulation. The second circuit is configured to generate a second clock signal based on the first clock signal and the phase difference. Jitter is added to second clock signal. The third circuit is configured to demodulate the data signal by comparing an amplitude of each pulse of the data signal with a threshold value at a timing synchronized to the second clock signal added the jitter. The processing circuit is configured to count the number of errors in the demodulated data signal and then calibrate the threshold value based on the counted number of errors.