DAC Common-Mode Adaptation for Full Dynamic Range

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Solution Overview

Problem

Conventional digital-to-analog converters suffer from reduced dynamic range due to dropout voltages near the ground and power supply limits, leading to signal clipping and reduced amplitude in these zones.

Innovation Solution

Implementing an output amplifier powered by a controllable power supply voltage and a ground reference voltage, with a common-mode adaptation circuit to position the common-mode voltage in the middle portion between the power supply and ground, allowing the dynamic range to be centered and avoiding clipping in both the upper and lower parts of the output signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power supply voltage of the output amplifier is increased to move the dropout voltage zone beyond the maximum output voltage level, then the upper clipping is avoided, but the lower clipping near the ground voltage remains

Engineering Contradiction:

Improveavoidance of upper signal clippingVSAvoidlower signal clipping near ground voltage

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the parameter of common-mode voltage level dynamically. By adjusting the common-mode voltage to be centered in the middle portion of the voltage interval between power supply and ground, the output signal's dynamic range is repositioned to avoid both upper and lower dropout zones, resolving the contradiction between avoiding upper and lower clipping

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic adaptation through the common-mode adaptation circuit that automatically positions the common-mode voltage according to the effective power supply voltage level. This dynamic adjustment allows the system to adapt to varying power supply conditions and maintain optimal operating range, avoiding clipping in both upper and lower portions of the signal

Inventive Principle:

Principle #15Dynamics

2Reliability

If the common-mode voltage is positioned in the middle portion of the voltage interval, then the dynamic range is centered and avoids dropout zones, but the circuit complexity increases due to the common-mode adaptation circuit

Engineering Contradiction:

Improvedynamic range centering and clipping avoidanceVSAvoidcommon-mode adaptation circuit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The common-mode adaptation circuit operates autonomously to self-adjust the common-mode voltage level based on the power supply voltage. The circuit automatically positions the common-mode voltage in the middle portion of the voltage interval without requiring external intervention, thereby improving reliability while minimizing the need for additional complex control mechanisms

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12375096B2Digital-to-analog converter and corresponding digital-to-analog conversion method

Publication Date: 2025.07.29 STMICROELECTRONICS (ROUSSET) SAS

AI summary

One embodiment provides a digital-to-analog converter that includes an output amplifier configured to be powered with a controllable power supply voltage and a ground reference voltage. The output amplifier is configured to generate an analog output signal having a dynamic range centered on a common-mode voltage. The output amplifier includes a common-mode adaptation circuit configured to position a level of the common-mode voltage at a level located in a middle portion of an interval of voltages located between the power supply voltage and the ground reference voltage, according to an effective level of the power supply voltage.