ADC Bias Current Reuse From Inactive DAC Cells
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Solution Overview
Problem
Existing analog-to-digital converters (ADCs) face challenges in enhancing dynamic range and reducing power consumption due to thermal noise and increased power consumption from bias current adjustments.
Innovation Solution
The solution involves using current cells in a digital-to-analog converter (DAC) to supply a bias current to the amplifier from inactive current cells, thereby reducing power consumption and enhancing dynamic range by reusing current from inactive cells as bias current for the amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bias current is increased to reduce thermal noise, then dynamic range is improved, but power consumption increases
Solution Approach 1:
The current cells in the DAC are designed to perform dual functions: converting digital signals to analog signals during the conversion phase, and providing bias current to the amplifier during the holding phase. This multi-functionality allows the system to maintain high dynamic range without requiring separate bias current sources, thereby reducing overall power consumption.
Solution Approach 2:
The system employs periodic switching between conversion mode and holding mode. During the holding phase, inactive current cells are redirected to provide bias current to the amplifier. This periodic redistribution of current allows the amplifier to receive adequate bias current only when needed, reducing unnecessary power consumption while maintaining dynamic range performance.
2Measurement precision
If separate bias current source is added to amplifier, then dynamic range is improved, but device complexity increases
Solution Approach 1:
The patent merges the bias current source function with the existing DAC current cells. Instead of adding a separate bias current generator circuit, the system utilizes the already-present current cells and adds switching mechanisms to redirect their output. This integration approach provides the necessary bias current while avoiding the complexity of independent bias current source circuits.
Solution Approach 2:
The DAC current cells serve themselves by providing their own output current as bias current to the amplifier during the holding phase. This self-service mechanism eliminates the need for external or separate bias current sources, reducing circuit complexity while ensuring the amplifier receives adequate bias current for optimal dynamic range performance.
Data Source
AI summary
An analog-to-digital converter (ADC) including: a digital-to-analog converter (DAC) including a plurality of current cells; and an amplifier including a bias terminal configured to receive a current supplied from the plurality of current cells, wherein each of the plurality of current cells includes: a power source; a first switch configured to couple the power source to input terminals of the amplifier; and a second switch configured to couple the power source to the bias terminal.