D/A Converter Voltage Selection Circuit with Localized Threshold Adjustment
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Solution Overview
Problem
D/A converters face challenges in achieving lower power consumption while maintaining proper voltage selection, especially when the power source voltage is reduced, due to difficulties in satisfying the on and off conditions of transistors.
Innovation Solution
A D/A converter configuration with a decoder, voltage generation circuit, and voltage selection circuit, where the second transistor in each selector block is set to a lower threshold voltage than the first transistor, and fine adjustments are made using gate lengths and substrate voltages, allowing for proper voltage selection even at lower power source voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power source voltage is reduced to lower power consumption, then power consumption is reduced, but the on and off conditions of transistors become harder to satisfy
Solution Approach 1:
The patent applies local quality by setting different threshold voltages for different transistors based on their position in the circuit. Specifically, transistors closer to the power source node are given higher threshold voltages while those farther away are given lower threshold voltages. This localized differentiation allows each transistor to operate reliably under the reduced power source voltage, resolving the contradiction between low power consumption and reliable transistor operation.
Solution Approach 2:
The patent changes the threshold voltage parameter of transistors according to their position in the selector block. By adjusting this critical parameter locally rather than uniformly, the system maintains proper transistor switching conditions even when the overall power source voltage is reduced, thereby achieving lower power consumption without sacrificing reliability.
2Use of energy by moving object
If the power source voltage is set low for lower power consumption, then power consumption decreases, but proper voltage selection becomes difficult
Solution Approach 1:
The patent implements local quality by differentiating threshold voltages across transistors in the voltage selection circuit based on their distance from the power source. This creates a gradient that facilitates proper voltage selection at each stage of the tournament-style selector blocks, enabling reliable operation with reduced power source voltage.
Solution Approach 2:
The patent modifies the threshold voltage parameter of transistors according to their specific position in the selection hierarchy. This parameter adjustment ensures that each selector block can properly distinguish and select voltages even under reduced power conditions, maintaining ease of operation while reducing power consumption.
Data Source
AI summary
A D/A converter includes a decoder, a voltage selection circuit, and a voltage selection circuit. The voltage selection circuit includes a plurality of stages of selector blocks in which output of a selector of the selector block at the previous stage is input to a selector of the selector block at the subsequent stage. A plurality of voltages are input to the selector block at the first stage, and the selector block at the final stage outputs a D/A-converted voltage. Each of the plurality of stages of selector blocks includes a plurality of transistors and, of the plurality of transistors forming the selector block, a second transistor on a far side from a power source node is set to a lower threshold voltage than that of a first transistor on a near side from the power source node.