Phase Skew Generator Using Charge Pump-Controlled VCDL
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Solution Overview
Problem
Generating precision phase skews using traditional delayed locked loops (DLLs) is difficult and expensive due to the need for a large number of delay line stages, which requires significant integrated circuit space and complex circuitry, affecting accuracy and power consumption.
Innovation Solution
A phase skew generator with an enhanced charge pump, capacitor, sample and hold circuit, and voltage-controlled delay line (VCDL) with only four delay stages, where the delay time is adjusted by controlling the current and operation regions of the charge pump, allowing for precise phase skew generation with reduced power consumption and IC space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of delay line stages are used in the VCDL to generate precision phase skew, then the phase skew accuracy is improved, but the integrated circuit area and device complexity increase significantly
Solution Approach 1:
The patent changes the operating parameters of the VCDL by controlling the charge pump current to adjust the delay time of each stage. By precisely controlling the current magnitude, the system achieves accurate phase skew generation with fewer stages, resolving the contradiction between accuracy and area.
Solution Approach 2:
The phase detector provides feedback about the phase skew between input and output clocks to the charge pump, which adjusts the VCDL delay accordingly. This closed-loop feedback mechanism enables precise phase skew control with a reduced number of delay stages, eliminating the need for numerous stages while maintaining accuracy.
2Measurement precision
If the number of delay stages in the VCDL is increased to adjust the ratio M, then the phase skew accuracy is improved, but the device complexity and power consumption increase
Solution Approach 1:
Instead of changing the number of delay stages to adjust ratio M, the patent changes the current control parameters of the charge pump. By varying the current magnitude, the system can achieve different phase skew ratios with a fixed, small number of VCDL stages, significantly reducing device complexity.
Solution Approach 2:
The patent makes the VCDL delay dynamically adjustable through charge pump current control rather than requiring a large number of configurable stages. This dynamic parameter adjustment approach reduces circuit complexity while maintaining the ability to achieve precise phase skew ratios.
3Adaptability or versatility
If a multiplexer is added to select the M stage output from a multi-stage configurable VCDL, then the adaptability is improved, but the measurement precision deteriorates due to significant multiplexer delay time
Solution Approach 1:
The patent removes the multiplexer from the signal path entirely. Instead of selecting outputs from multiple delay stages using a multiplexer, the system directly generates the desired phase skew by controlling the charge pump current, eliminating the source of delay uncertainty and improving measurement precision.
Solution Approach 2:
The patent changes the approach from spatial selection (multiplexer switching between stages) to parameter control (current magnitude adjustment). This parameter-based control method achieves the same adaptability without introducing multiplexer delay, thereby maintaining phase skew accuracy.
4Measurement precision
If more delay line stages are used to achieve the desired phase skew ratio, then the phase skew accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent achieves precise phase skew control by adjusting the charge pump current parameter rather than increasing the number of delay stages. This parameter-based approach reduces the number of active circuit elements, thereby lowering power consumption while maintaining accuracy.
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
The solution achieves significant reductions in the number of delay line stages and power consumption while maintaining precision phase skew accuracy, addressing the limitations of traditional DLLs and improving electromagnetic performance.
Implementation Method 1
The charge pump and loop filter translates phase error to voltage signal, which is then provided to an input of the VCDL
Implementation Method 2
In response to a magnitude of the voltage signal input, the VCDL adjusts the delay time of the input clock
Data Source
AI summary
A method and apparatus of generating precision phase skews is disclosed. In some embodiments, a phase skew generator includes: a charge pump having a first mode of operation and a second mode of operation, wherein the first mode of operation provides a first current path during a first time period, and the second mode of operation provides a second current path during a second time period following the first time period, a sample and hold circuit, coupled to a capacitor, and configured to sample a voltage level of the capacitor at predetermined times and provide an output voltage during a third time period following the second time period; and a voltage controlled delay line, coupled to the sample and hold circuit, and having M delay line stages each configured to output a signal having a phase skew offset with respect to preceding or succeeding signal.