Reference Voltage Circuit Reduces Delay Fluctuations

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Solution Overview

Problem

Conventional semiconductor integrated circuit devices face challenges in reducing delay time fluctuations due to process and temperature variations without increasing consumption current, leading to errors in access time.

Innovation Solution

A reference voltage generating circuit using low threshold voltage PMOS and NMOS transistors in series with a resistor, along with a temperature sensor circuit, adjusts the reference voltage to mitigate the effects of process and temperature fluctuations, thereby controlling consumption current and delay characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If low Vt transistors are used to reduce delay time, then operation speed is improved, but consumption current increases due to threshold voltage variation

Engineering Contradiction:

Improveoperation speedVSAvoidconsumption current

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent implements a feedback mechanism where the reference voltage is continuously monitored and adjusted based on detected threshold voltage variations of low Vt transistors. The control circuit receives information about transistor characteristic changes and dynamically corrects the reference voltage to maintain optimal operation speed while compensating for the increased consumption current effect

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the reference voltage parameter in response to detected threshold voltage variations. By adjusting this critical parameter based on actual transistor characteristics, the system maintains optimal operation speed across different process conditions without being constrained by fixed voltage levels that would otherwise require higher consumption current

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If low Vt transistor threshold voltage varies downward to reduce operation delay, then delay time is reduced, but operation current and leak current increase

Engineering Contradiction:

Improvedelay timeVSAvoidoperation current and leak current

Core Design Contradiction:

Loss of timeVSLoss of energy

Solution Approach 1:

The monitoring circuit detects actual threshold voltage variations and feeds this information back to the control circuit, which then adjusts the reference voltage to compensate for the increased operation and leak current effects, maintaining optimal timing characteristics

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from static reference voltage to dynamic adjustment, where the reference voltage is continuously adapted based on real-time detection of transistor threshold voltage variations, allowing optimal performance across varying current consumption conditions

Inventive Principle:

Principle #15Dynamics

3Use of energy by moving object

If power supply voltage is lowered to reduce consumption current, then consumption current is reduced, but the influence of threshold voltage variation is increased, further increasing delay time fluctuation

Engineering Contradiction:

Improveconsumption currentVSAvoiddelay time fluctuation

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The feedback mechanism detects threshold voltage variations and compensates for their amplified effect by adjusting the reference voltage, thereby maintaining stable delay time characteristics even when operating at lower power supply voltages with reduced consumption current

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection and compensation of threshold voltage variations before they significantly impact delay time, allowing the circuit to maintain reliability at lower operating voltages where the influence of variations would otherwise be magnified

Inventive Principle:

Principle #10Preliminary action

4Reliability

If low Vt transistor characteristics vary due to process fluctuation, then delay time fluctuation is reduced slightly, but access time error increases

Engineering Contradiction:

Improvedelay time fluctuationVSAvoidaccess time error

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The feedback system continuously monitors threshold voltage variations and adjusts the reference voltage to compensate, thereby maintaining precise access time control even when low Vt transistor characteristics vary due to process fluctuation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The reference voltage parameter is dynamically adjusted in response to detected transistor characteristic variations, compensating for the effects of process fluctuation and maintaining accurate access time measurements

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7642843B2Reference voltage generating circuit and semiconductor integrated circuit device

Publication Date: 2010.01.05 MICRON TECHNOLOGY INC

AI summary

A reference voltage generating circuit comprises: a monitor circuit, including a low threshold voltage PMOS transistor, a low threshold voltage NMOS transistor, and a resistor having a predetermined resistance which are connected in series, for generating a reference voltage at one end; and an additional circuit for supplying a monitor current to the monitor circuit and for controlling the other end of the monitor circuit to be at a constant voltage, wherein a voltage value of the reference voltage is corrected within a range corresponding to a process fluctuation from a predetermined center value, based on the monitor current changing in response to the process fluctuation.