Resistor DAC Switch-Bridge Gain Correction for Voltage Drop Errors
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Solution Overview
Problem
Digital-to-Analog Converters (DACs) introduce current defects due to voltage drops across switches, leading to gain errors and drift, which affect circuit performance, and existing correction methods either introduce new errors or distortions.
Innovation Solution
A compensation circuit is connected to the DAC circuit to generate a compensation current that accounts for voltage drops across switches, using a voltage generator circuit and amplifiers to provide a 'gained up' voltage, ensuring balanced current flow without introducing new errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If switch size is reduced to improve integration, then manufacturing precision improves, but voltage drops across switches increase causing gain errors
Solution Approach 1:
The patent measures the voltage drop across each switch (converting the harmful effect into useful information) and uses this measurement to generate a compensation current that cancels the harmful effect. The harmful voltage drop becomes the basis for creating the correction signal.
Solution Approach 2:
The patent implements a feedback mechanism where the voltage drop across each switch is measured and fed back to a compensation circuit. This feedback loop allows the system to automatically adjust and cancel the gain errors caused by voltage drops, maintaining precision despite switch size reduction.
2Measurement precision
If compensation current is added to correct voltage drops, then gain error is reduced, but device complexity increases
Solution Approach 1:
The patent introduces compensation circuits as intermediary elements between the switches and the rest of the DAC circuitry. These intermediaries measure voltage drops and generate compensating signals, isolating the core DAC function from the correction functionality and managing complexity through functional separation.
Solution Approach 2:
The compensation circuits are self-regulating systems that automatically measure their own operating conditions (voltage drops across switches) and generate appropriate compensation currents without external intervention. Each compensation circuit serves itself by using its own measurements to correct its own errors.
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
The compensation circuit effectively corrects current defects caused by voltage drops, maintaining circuit performance and linearity, allowing for more aggressive shrinking of switch sizes or greater linearity at a given size without disrupting voltage-to-current conversion.
Implementation Method 1
measuring a voltage drop across a first switch of a switch bridge in the DAC circuit
Implementation Method 2
providing, based on the measured voltage drop and the received information, a first compensation current to a first leg of the switch bridge
Data Source
AI summary
Systems and techniques for Digital-to-Analog Converter (DAC) gain correction are described herein. A digital-to-analog converter (DAC) circuit can include a switch bridge circuit having a first leg and a second leg that define respective mutually exclusive first and second DAC signal paths. The DAC circuit can further include a first compensation circuit configured to provide a first compensation current to the first leg of the switch bridge to compensate for a current defect caused by a voltage drop across a portion of the first DAC signal path. The DAC circuit can also include a second compensation circuit configured to provide a second compensation current to a second leg of the switch bridge to compensate for a voltage drop across a portion of the second DAC signal path. The DAC circuit can be included in a larger circuit such as a continuous time sigma delta (CTSD) analog-to-digital converter (ADC).