Delay-Based Frequency Multiplier Calibration for Clock Error Correction
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Solution Overview
Problem
Existing electronic systems face challenges in accurately generating clock signals with higher frequencies due to errors introduced by frequency multipliers, such as frequency and duty cycle errors, which are affected by process variations, operational conditions, and noise.
Innovation Solution
The proposed solution involves an apparatus that includes a delay-based frequency multiplier and an error detection circuit. The error detection circuit measures the time difference between edges of the clock signal and its delayed version to detect period errors, which are then used to calibrate the delay-based frequency multiplier, thereby correcting frequency and duty cycle errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a frequency multiplier is used to generate higher frequency clock signals, then the clock frequency is improved, but frequency error and duty cycle error increase due to process variations, operational conditions, and noise
Solution Approach 1:
The patent implements a feedback mechanism where the generated high-frequency clock signal is delayed by a controllable delay element, and the time difference between the original and delayed signals is measured. This time difference information is fed back to adjust the delay element's delay amount, creating a closed-loop system that automatically corrects frequency and duty cycle errors without requiring external calibration equipment.
Solution Approach 2:
The system uses its own generated clock signal for calibration purposes. By dividing the high-frequency clock signal and comparing it with a delayed version of itself, the system performs self-diagnosis and self-correction of frequency and duty cycle errors, eliminating the need for external reference sources or calibration equipment.
2Reliability
If process variations and operational condition changes occur, then the frequency multiplier introduces more errors, but the system should maintain accurate clock signal generation
Solution Approach 1:
The closed-loop feedback mechanism continuously monitors the time difference between original and delayed clock signals and dynamically adjusts the delay element to compensate for errors caused by process variations and operational condition changes, maintaining accurate clock signal generation across different conditions.
Solution Approach 2:
The delay element is designed to be dynamically adjustable rather than fixed, allowing the system to adapt its delay amount in real-time based on the measured time difference, thereby compensating for variations in process conditions and operational parameters.
3Measurement precision
If an error detection and calibration circuit is added to the frequency multiplier, then frequency and duty cycle errors are reduced, but the device complexity increases
Solution Approach 1:
The calibration circuit uses the system's own internal resources - the generated clock signal itself and existing delay elements - to perform error detection and correction, avoiding the need for external reference clocks or complex calibration equipment, thereby limiting the increase in device complexity.
Solution Approach 2:
The delay element serves dual purposes: it is part of the normal clock signal generation path and simultaneously functions as a calibration adjustment element. The time measurement circuit also serves both error detection and calibration control functions, reducing the need for separate dedicated calibration components.
Data Source
AI summary
In some examples, an apparatus includes a delay-based frequency multiplier and an error detection circuit. The delay-based frequency multiplier has a clock input, a multiplier clock output, and a delay calibration input. The error detection circuit has a detection input and a detection output. The detection input is coupled to the multiplier clock output, and the detection output is coupled to the delay calibration input. The error detection circuit is configured to receive a clock signal at the detection input, and provide a period error signal at the detection output based on a time difference between a first edge of the clock signal and a second edge of a delayed version of the clock signal.