SAR ADC Reference Voltage Switching for Lower Conversion Power
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Solution Overview
Problem
Successive-approximation-register (SAR) analog-to-digital converters (ADCs) consume a significant amount of power during signal conversion.
Innovation Solution
The proposed analog-to-digital converter includes a comparator, control logic, and a reference voltage adjustment circuit with pull-up and pull-down circuits. The control logic outputs control signals based on the comparator's output, and these signals adjust the reference voltages applied to capacitor arrays, optimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a SAR ADC uses conventional capacitor arrays with fixed reference voltages, then the conversion function is achieved, but power consumption is high
Solution Approach 1:
The capacitor array is divided into multiple groups, with each group having independently controllable switches that can selectively connect to different reference voltage levels. This segmentation allows only the necessary capacitor groups to be activated during each conversion cycle, reducing overall power consumption while maintaining the conversion function.
Solution Approach 2:
The reference voltage connections are made dynamic through control switches that can reconfigure which capacitor groups connect to which reference voltage levels based on the conversion stage. This dynamic reconfiguration enables the circuit to adapt its power consumption to the actual conversion needs, avoiding continuous full-power operation.
2Reliability
If reference voltages are continuously applied to all capacitors, then the ADC operation is maintained, but dynamic power consumption increases
Solution Approach 1:
Reference voltages are applied periodically rather than continuously, synchronized with the conversion phases. During non-active phases, the connection switches disconnect the reference voltages from the capacitor arrays, eliminating dynamic power consumption during these periods while ensuring reference voltages are available when needed for conversion operations.
Solution Approach 2:
Different capacitor groups receive reference voltage connections selectively based on their specific function in the conversion process. Only the capacitor groups currently needed for the conversion operation maintain active reference voltage connections, while others are disconnected, thereby reducing overall dynamic power loss without compromising conversion reliability.
Data Source
AI summary
An analog-to-digital converter is provided. An analog-to-digital converter includes a comparator including a first input node receiving an output of a plurality of first unit capacitors and a second input node receiving an output of a plurality of second unit capacitors, a control logic configured to output first and second control signals on the basis of an output signal of the comparator, and a reference voltage adjustment circuit configured to adjust an output voltage provided to the comparator on the basis of the first and second control signals. The reference voltage adjustment circuit comprises a first pull-up circuit configured to apply a first reference voltage to each of the plurality of first unit capacitors and a first pull-down circuit configured to apply a second reference voltage to each of the plurality of second unit capacitors, based on v.