Multi-Phase Clock Generator Locking With Duty Cycle Error Tolerance
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Solution Overview
Problem
Conventional multi-phase clock signal generators face difficulties in initializing clock signals with duty cycle distortion, leading to improper phase relationships and potential failure in high-speed applications due to limited delay range and slow locking times.
Innovation Solution
The proposed system employs a multi-phase clock signal generator with a delay line having multiple delay elements per tap and a phase detector that uses a single adjustment signal to lock C0, C180, and C360 signals, along with a duty cycle distortion tolerance delay element to ensure accurate phase alignment, even with duty cycle errors, by utilizing multiple bias voltages and a charge-pump and loop filter for adaptive delay control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional multi-phase clock signal generator is used, then the system can operate over a wide range of frequencies, but the initialization is slow and inaccurate due to duty cycle distortion
Solution Approach 1:
The delay line is divided into multiple independently controllable delay elements (first, second, third delay elements) rather than a single unified delay mechanism. This segmentation allows selective adjustment of different delay portions to compensate for duty cycle distortion and achieve accurate phase relationships faster.
Solution Approach 2:
The delay elements are made dynamically adjustable through separate control signals that can be modified in real-time based on detected phase errors. This dynamic control enables the system to adapt to duty cycle distortion and lock onto correct phase relationships more quickly than fixed delay configurations.
2Measurement precision
If multiple delay elements per tap are used, then the delay range and locking accuracy are improved, but the device complexity increases
Solution Approach 1:
Different delay elements are assigned different control characteristics - the first delay element responds to a first control signal, the second to a second control signal, and the third to a third control signal. This local differentiation allows precise control of specific delay portions without requiring complex global control mechanisms.
Solution Approach 2:
A phase detector monitors the phase relationship between clock signals and provides feedback control signals to adjust the delay elements. This feedback mechanism automatically corrects phase errors without requiring complex manual calibration or overly sophisticated control logic.
3Adaptability or versatility
If a fixed timing circuit is used to generate quadrature signals, then the circuit is simple, but it cannot adapt to a wide range of clock frequencies
Solution Approach 1:
The delay elements are made dynamically adjustable through separate control signals that can be modified in real-time based on detected phase errors. This dynamic control enables the system to adapt to duty cycle distortion and lock onto correct phase relationships more quickly than fixed delay configurations.
Solution Approach 2:
The delay characteristics of the delay elements are made variable through control signals that adjust the delay amount based on the operating frequency and duty cycle conditions. This parameter adjustment allows the circuit to maintain accurate phase relationships across a wide frequency range without requiring complete circuit reconfiguration.
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
This approach enables fast and accurate initialization of multi-phase clock signals across a wide range of frequencies, effectively addressing duty cycle distortion and ensuring precise phase relationships, thereby improving the reliability and speed of clock signal generation.
Implementation Method 1
a charge-pump and loop filter configured to generate a control signal in response to the second signal to adjust the delay of the delay elements
Data Source
AI summary
Multi-phase signal generators and methods for generating multi-phase signals are described. In one embodiment, the clock generator generates quadrature clock signals including those having 90, 180, 270 and 360 degrees phase difference with a first clock signal. One of the intermediate clock signals may be used as an enable signal to guide locking of all signals. For example, the 180 degree clock signal may be inverted and used as an enable signal to guide locking of the initial and 360 degree signals in a single phase adjustment procedure. The 0 and 360 degree signals may be delayed before their phase is compared to compensate for duty cycle error in the clock signals.