MOSFET Duty Cycle Controller for PVT-Stable Clock Timing
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Solution Overview
Problem
In high-speed data processing applications, maintaining a consistent clock duty cycle is challenging due to Process-Voltage-Temperature (PVT) and component mismatches, which cause significant variations.
Innovation Solution
A duty cycle controller (DCC) with a tuning circuit comprising field-effect transistors and an edge delay circuit is used to mitigate these variations by selectively activating and deactivating MOSFETs to adjust the capacitance and delay of the clock signal, ensuring the duty cycle remains within a target range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional clock duty cycle control is used, then the circuit is simple, but the clock duty cycle varies widely due to PVT and component mismatches
Solution Approach 1:
The patent implements dynamic duty cycle adjustment by selectively activating or deactivating specific transistors (e.g., Q1-Q4, Q5-Q8) based on temperature conditions. This allows the circuit to adapt its configuration dynamically, changing the effective capacitance and resistance values to compensate for PVT variations and maintain stable clock duty cycle across different operating conditions.
Solution Approach 2:
The patent changes physical parameters (capacitance values, resistance values) by selectively connecting different capacitor-transistor combinations based on temperature. For example, at different temperatures, different transistors are activated to change the effective capacitance seen by the clock signal, thereby adjusting the duty cycle to compensate for temperature-induced variations.
2Measurement precision
If temperature-specific coefficients are used for duty cycle control, then the duty cycle accuracy improves, but the device complexity and calibration requirements increase
Solution Approach 1:
The patent segments the temperature compensation function into multiple discrete transistor pairs (Q1-Q4, Q5-Q8, etc.), each responsible for a specific temperature range or compensation level. This segmentation allows the circuit to achieve temperature-specific duty cycle adjustment without requiring complex external calibration, as each segment is designed to activate automatically based on temperature conditions.
Solution Approach 2:
The circuit achieves automatic temperature compensation through self-service mechanisms where the transistors are configured to activate/deactivate based on inherent temperature-dependent characteristics. The design uses the natural PVT variations to trigger the appropriate transistor configurations, eliminating the need for external temperature sensors or complex calibration procedures.
3Reliability
If more transistors are added to the tuning circuit for better duty cycle control, then the duty cycle stability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent merges multiple functions into the same transistor components. The transistors serve dual purposes: they act as switches for selecting different capacitance values and simultaneously provide temperature compensation. This merging reduces the need for additional precision-matched components, as the existing transistors are utilized for multiple functions, thereby reducing manufacturing precision requirements.
Solution Approach 2:
The transistor components are designed with multi-functionality, serving as both switches and temperature-compensation elements. For example, the same transistors that select capacitance values also provide the temperature-dependent characteristics needed for duty cycle stabilization. This universality reduces the total number of precision components needed, lowering manufacturing precision requirements.
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 effectively stabilizes the clock duty cycle across various temperatures and conditions, providing a linear tuning range and minimizing the need for temperature-specific coefficients, thus ensuring reliable high-speed data processing.
Implementation Method 1
The first field-effect transistor implements a capacitor
Implementation Method 2
The tuning circuit is configured to activate the second field-effect transistor to connect a source and a drain of the first field-effect transistor to a voltage source
Implementation Method 3
The tuning circuit is configured to activate the third field-effect transistor to connect the source and the drain of the first field-effect transistor to a ground
Data Source
AI summary
An apparatus is disclosed that includes a duty cycle controller. The duty cycle controller includes a tuning circuit comprising a first field-effect transistor. The first field-effect transistor is configured to implement a capacitor. The duty cycle controller further includes an edge delay circuit. The edge delay circuit includes a second field-effect transistor that, when activated by an input clock signal of the duty cycle controller, is configured to connect a voltage source to an output clock signal of the duty cycle controller. The edge delay circuit further includes a third field-effect transistor that, when activated, is configured to connect the first field-effect transistor of the tuning circuit to the output clock signal.