Clock Skew Calibration in Semiconductor Packages Using Track Signals
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Solution Overview
Problem
Modern semiconductor devices face challenges in maintaining precise synchronization of high-speed data communication due to clock skew caused by variations in propagation delays, capacitive and inductive effects, and temperature and process variations, leading to data setup and hold violations and synchronization failures.
Innovation Solution
A semiconductor package and operating method that utilizes a receiver and controller to generate internal clock signal pairs of different phases, detect skew status through sampling, and adjust phases based on skew detection to align clock signals with data signals, using a predefined track signal and synchronized internal clock signal pairs to ensure synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operating frequency of the semiconductor device is increased to improve communication speed, then productivity is improved, but clock skew increases causing synchronization failures and data setup/hold violations
Solution Approach 1:
The patent applies preliminary action by performing skew calibration before normal data transmission. A track signal is transmitted and used to measure propagation delays in advance, allowing the system to pre-calculate compensation values that are stored and applied during subsequent operations. This ensures synchronization is established before high-speed communication begins, preventing skew-related failures.
Solution Approach 2:
The patent implements feedback by continuously monitoring the skew status between clock signals and data signals through sampling. The measured skew information is fed back to adjust the timing of internal clock signals, creating a closed-loop control system that dynamically compensates for skew variations caused by temperature, voltage, or process changes, thereby maintaining synchronization reliability at high operating frequencies.
2Measurement precision
If skew calibration is performed using ideal clock signals, then measurement precision is improved, but reliability deteriorates because actual clock signals have non-50% duty cycles causing inaccurate skew detection
Solution Approach 1:
The patent applies parameter changes by adapting the skew detection method to work with actual clock signal characteristics rather than idealized assumptions. Instead of assuming 50% duty cycles, the system measures the actual duty cycle of received clock signals and uses this information to adjust sampling timing and skew calculation, ensuring accurate measurements reflect real operating conditions.
Solution Approach 2:
The patent implements self-service by using the actual clock signals themselves as the reference for skew measurement, rather than requiring separate ideal clock sources. The system extracts timing information directly from the incoming clock signals and uses these same signals to perform the calibration, making the process self-contained and reliable without external ideal references.
3Measurement precision
If the number of sampling points for skew detection is increased to improve measurement precision, then device complexity increases due to additional circuitry and processing requirements
Solution Approach 1:
The patent applies partial action by using a minimal sufficient number of sampling points rather than exhaustive sampling. The system determines that sampling at specific critical points (such as rising and falling edges of clock signals) provides adequate skew measurement without requiring continuous or excessive sampling, thus achieving acceptable precision with reduced circuit complexity.
Solution Approach 2:
The patent implements segmentation by dividing the skew detection process into distinct phases: initial calibration phase using track signals, and operational phase using data signals. Each phase uses appropriately optimized sampling strategies, with the calibration phase requiring more comprehensive sampling that is performed only once or periodically, while normal operation uses lighter sampling, thus reducing overall complexity requirements.
Data Source
AI summary
A semiconductor device includes a receiver and a controller. The receiver is configured to sample a data signal and a track signal received through data lanes in response to rising edges of first and second internal clock signal pairs. The controller is configured to detect a skew status between the track signal and the first and second internal clock signal pairs, based on the number of times a specific logic level of the track signal is sampled in synchronization with each of the first and second internal clock signal pairs, and provide the receiver with a clock shift signal for calibrating a clock skew, based on the skew status.