Dynamic Amplifier Reference Biasing for Larger Output Swing

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Solution Overview

Problem

Dynamic amplifiers face limitations due to the decreasing threshold voltage in CMOS technology, which restricts the output signal swing and affects their performance in circuit systems.

Innovation Solution

The proposed amplifier circuit incorporates a reference voltage generation circuit that stabilizes the source-gate voltages of transistors by generating reference voltages based on input or output common-mode voltages, reducing susceptibility to common-mode voltage fluctuations and enhancing reliability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If dynamic amplifiers are used to avoid static current consumption, then power consumption is reduced, but the output signal swing is limited due to threshold voltage constraints

Engineering Contradiction:

Improvepower consumptionVSAvoidoutput signal swing

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent implements dynamic switching of transistor gates using clock signals to enable the amplifier to operate in different states. The dynamic operation allows the amplifier to achieve large output swings by periodically enabling and disabling the current path, avoiding the need for a continuously conducting current source that would be limited by threshold voltage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameters of the amplifier by using dynamic voltage levels on the gate terminals. By applying clock signals that swing between different voltage levels, the transistors can operate in saturation, triode, or cutoff regions, enabling the output to achieve full rail-to-rail swings without being constrained by the threshold voltage of a continuously conducting current source.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If dynamic amplifiers operate without fixed DC current, then static power consumption decreases, but susceptibility to common-mode voltage fluctuations increases

Engineering Contradiction:

Improvestatic power consumptionVSAvoidsusceptibility to common-mode voltage fluctuations

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs feedback mechanisms where the differential pair transistors automatically balance their operation in response to common-mode voltage changes. The dynamic switching and differential configuration create inherent feedback that maintains signal integrity despite common-mode fluctuations, improving reliability without requiring additional static current for stabilization.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses asymmetric switching control where the differential pair transistors are switched in complementary fashion. This asymmetric operation allows the circuit to reject common-mode signals while maintaining differential signal amplification, reducing susceptibility to common-mode voltage fluctuations during dynamic operation.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS20240396507A1Amplifier circuit

Publication Date: 2024.11.28 REALTEK SEMICON CORP

AI summary

An amplifier circuit includes four transistors, four switches, a capacitor, and a reference voltage generation circuit. One terminal of the capacitor is coupled to a first reference voltage, and the other terminal of the capacitor is coupled to a second reference voltage. The reference voltage generation circuit is coupled to the input terminals or the output terminals of the amplifier circuit and generates the first reference voltage and/or the second reference voltage according to the input voltages or the output voltages of the amplifier circuit.