Reference Voltage Buffer Circuit for Fast Low-Power ADC Loading

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Solution Overview

Problem

Existing reference voltage buffers in pipeline ADCs require high-speed operation to maintain constant reference voltages, but this typically results in excessive power consumption.

Innovation Solution

A reference voltage buffer circuit using an operational trans-conductance amplifier with a shunt capacitor and resistor configuration, where the shunt capacitor's impedance is significantly smaller than the load circuit's impedance, allowing for fast reaction without excessive power consumption by utilizing a negative feedback mechanism to offset current through a resistor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If high-speed operation is used to maintain constant reference voltages, then voltage stability is improved, but power consumption increases excessively

Engineering Contradiction:

Improvereference voltage stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the buffer circuit's operating state adjustable between high-speed and low-power modes. The operational trans-conductance amplifier's transconductance can be dynamically adjusted based on operational requirements, allowing the system to switch between maintaining high voltage stability (when speed is needed) and reducing power consumption (when stability can be maintained at lower speed).

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the transconductance parameter of the operational trans-conductance amplifier to resolve the contradiction. By adjusting the transconductance value, the buffer can operate at different speed-power tradeoff points. Lower transconductance reduces power consumption while still maintaining adequate voltage stability, and higher transconductance provides faster response when needed.

Inventive Principle:

Principle #35Parameter changes

2Speed

If high transconductance is used in the operational trans-conductance amplifier, then fast reaction speed is improved, but power consumption increases

Engineering Contradiction:

Improvereaction speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent makes the transconductance dynamic rather than fixed. The operational trans-conductance amplifier's transconductance can be adjusted based on the operational phase or requirements, allowing fast reaction speed when needed while reducing power consumption during periods when high speed is not critical.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent directly addresses this contradiction by changing the transconductance parameter of the operational trans-conductance amplifier. By optimizing and dynamically adjusting this parameter, the system achieves fast reaction speed when required while minimizing power consumption during normal operation or when speed requirements are lower.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If low transconductance is used in the operational trans-conductance amplifier, then power consumption is reduced, but reaction speed decreases

Engineering Contradiction:

Improvepower consumptionVSAvoidreaction speed

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The patent resolves this contradiction by making the transconductance adjustable rather than fixed at a low value. When fast reaction is needed, the transconductance can be increased temporarily. When power consumption is the priority and speed requirements are minimal, the transconductance remains low, thus achieving a dynamic balance between power consumption and reaction speed.

Inventive Principle:

Principle #15Dynamics

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

Enables fast reaction to maintain constant reference voltages with reduced power consumption by allowing the operational trans-conductance amplifier to operate at lower transconductance while maintaining high-speed performance.

Implementation Method 1

an output terminal of the OTA shunt to a ground node via a shunt capacitor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a resistor coupling the output terminal of the OTA to the feedback node

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 3

an OTA (operational trans-conductance amplifier) with a positive input terminal coupled to a reference voltage, a negative input terminal coupled to a feedback node, and an output terminal

Methodology Applied

Scientific EffectTransconductance:

Data Source

PatentUS8362831B2Reference voltage buffer and method thereof

Publication Date: 2013.01.29 REALTEK SEMICON CORP

AI summary

An apparatus comprises: an OTA (operational trans-conductance amplifier) with a positive input terminal coupled to a reference voltage, a negative input terminal coupled to a feedback node, and an output terminal shunt to a ground node via a shunt capacitor; a resistor coupling the output terminal of the OTA to the feedback node; and a load circuit coupled to the feedback node via a switch controlled by a logical signal, wherein: an impedance of the shunt capacitor is substantially smaller than an input impedance of the load circuit. In an embodiment, the load circuit is a switch capacitor circuit. A corresponding method using an OTA is also provided.