Body Bias Voltage Generator for MOS Threshold Control
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Solution Overview
Problem
In system-on-chip designs, the operational speed is compromised due to high threshold voltage of MOS transistors leading to increased signal transfer delay, while low threshold voltage results in leakage current issues, necessitating effective control of threshold voltage based on operational frequency.
Innovation Solution
A body bias voltage generator is implemented, utilizing a voltage divider with a switched capacitor circuit and resistor circuit operating on distinct clock signals to generate body bias voltages that adjust the threshold voltage of n-type and p-type MOS transistors, ensuring optimal operational speed and reduced leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the threshold voltage of MOS transistor is increased, then leakage current is reduced, but operational speed decreases
Solution Approach 1:
The patent implements dynamic threshold voltage control by adjusting the body bias voltage according to operational frequency. The body bias voltage generator dynamically modifies the threshold voltage of MOS transistors based on real-time frequency detection, allowing the system to optimize between leakage current reduction and operational speed enhancement rather than using a fixed threshold voltage
Solution Approach 2:
The patent changes the electrical parameter (threshold voltage) of the MOS transistor by applying adjustable body bias voltage. The body bias voltage generator produces variable voltage levels that directly alter the threshold voltage characteristic, enabling the system to adapt the transistor's electrical properties to different operational requirements
2Speed
If the threshold voltage of MOS transistor is decreased, then operational speed is improved, but leakage current increases
Solution Approach 1:
The system dynamically adjusts threshold voltage based on operational frequency through the body bias voltage generator. When high operational speed is required, the generator reduces threshold voltage by applying appropriate body bias; when power efficiency is prioritized, it increases threshold voltage to reduce leakage, creating a dynamic optimization mechanism
Solution Approach 2:
The patent incorporates frequency detection feedback to control the body bias voltage generator. The detected operational frequency feeds back to the voltage generator, which automatically adjusts the body bias voltage to achieve the desired threshold voltage level, creating a closed-loop control system that balances speed and leakage current
3Productivity
If body bias voltage is adjusted to optimize threshold voltage, then system performance is improved, but device complexity increases
Solution Approach 1:
The body bias voltage generator serves multiple functions: it detects operational frequency, generates appropriate body bias voltage, and adjusts threshold voltage for different transistor types (NMOS and PMOS). This multi-functional component consolidates what could be separate circuits into a single integrated unit, reducing overall device complexity while maintaining performance optimization capabilities
Solution Approach 2:
The system performs self-adjustment through the body bias voltage generator that automatically detects frequency and generates the necessary body bias voltage without external intervention. The frequency detection and voltage adjustment processes are self-contained within the generator circuit, eliminating the need for complex external control mechanisms
Data Source
AI summary
A system-on-chip includes a body bias voltage generator having a voltage divider and a filter. The voltage divider includes a switched capacitor circuit and a resistor circuit. The switched capacitor circuit operates based on a first clock signal and a second clock signal. The resistor circuit outputs a first voltage through a first node, which is coupled to the switched capacitor circuit and the resistor circuit. The first and second clock signals have a same frequency. The filter performs a filtering operation on the first voltage to generate a body bias voltage.