Reference Current Generator Offset Compensation

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Solution Overview

Problem

Conventional semiconductor memory devices face instability in generating a reference current due to mismatches in transistor characteristics, leading to offset deviations that affect the reliability and productivity of chip operations.

Innovation Solution

A semiconductor device with a Widlar-type reference current generator, current-voltage converter, and analog-digital converter that adjusts the reference current based on a digital code value, compensating for transistor mismatches by controlling the number of enabled NMOS transistors to stabilize the reference current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If a conventional voltage down-converter using PMOS transistor is used, then the internal voltage can be generated at lower levels to reduce power consumption, but the output voltage varies due to process variations in transistor characteristics

Engineering Contradiction:

Improvepower consumptionVSAvoidoutput voltage stability

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the reference voltage generated by the Widlar circuit is fed back to control the current source, creating a self-regulating system that compensates for transistor parameter variations and stabilizes the output voltage

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent utilizes the Widlar circuit configuration which changes the operating parameters of the transistors by introducing a specific resistor network that alters the current-voltage characteristics, enabling stable operation despite process variations

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If transistor characteristics vary due to process changes, then manufacturing cost is reduced, but the reference current becomes unstable and offset deviations occur

Engineering Contradiction:

Improvemanufacturing costVSAvoidreference current stability

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of transistor mismatch into a beneficial compensation mechanism by designing the Widlar circuit such that the voltage drop across the compensation resistor counteracts the offset deviations caused by transistor characteristic variations

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The circuit performs self-compensation where the generated reference voltage automatically adjusts the current through the transistor pair, eliminating the need for external calibration or trimming mechanisms

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8970257B2Semiconductor device for offset compensation of reference current

Publication Date: 2015.03.03 MIMIRIP LLC

AI summary

A semiconductor device includes a reference current generator suitable for generating a reference current, a current-voltage converter suitable for generating a first reference voltage and a second reference voltage in response to the reference current, and an analog-digital converter suitable for generating a digital code value based on a voltage difference between the first and second reference voltages, wherein the reference current generator includes a current control unit for controlling the reference current in response to the digital code value.