Comparator Current Control for Low-Power High-Speed A/D Conversion
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Solution Overview
Problem
In electronic circuits performing A/D conversion, reducing power consumption while maintaining high-speed conversion characteristics is challenging, as lowering the electric current supply slows down the comparison unit's response, degrading conversion performance.
Innovation Solution
A signal processing apparatus with a control unit that manages electric current at the differential stage of a comparison unit, reducing current during periods other than the comparison period by using multiple pairs of electric current source units and switches in parallel, and adjusting gate potentials to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lower electric current is supplied to the comparison unit to suppress power consumption increase, then power consumption is reduced, but the response speed of the comparison unit slows down, causing degradation of A/D conversion performance
Solution Approach 1:
The patent applies dynamics by making the electric current supply to the comparison unit variable rather than constant. The control unit dynamically adjusts the current amount based on the operational phase: providing higher current during comparison periods to maintain fast response, and lower current during other periods to reduce power consumption. This temporal variation in current supply resolves the contradiction between power consumption and response speed.
Solution Approach 2:
The patent implements periodic action by alternating between high-current comparison periods and low-current non-comparison periods. The comparison unit operates in cycles where it receives sufficient current only when performing comparison operations, and reduces current during idle or non-critical periods. This periodic modulation of current supply achieves both low average power consumption and maintained response speed when needed.
2Use of energy by moving object
If lower electric current is supplied to the comparison unit, then power consumption is suppressed, but A/D conversion performance and high-speed characteristic are degraded
Solution Approach 1:
The control unit dynamically adjusts the electric current supplied to the comparison unit based on operational requirements. During comparison periods when A/D conversion performance is critical, higher current is provided to maintain fast conversion speed. During other periods, current is reduced to lower power consumption. This dynamic current control resolves the contradiction between power consumption and conversion performance.
Solution Approach 2:
The patent changes the electrical parameter (current amount) supplied to the comparison unit based on operational phase. By varying the current parameter between high and low levels depending on whether the unit is in comparison period or other period, the system achieves both low power consumption and maintained conversion performance when needed.
Data Source
AI summary
The present technology relates to a signal processing apparatus, a control method, an image pickup element, and an electronic appliance that achieve the suppression of an increase in electric power consumption. The signal processing apparatus may be configured to control an amount of electric current at a differential stage in a comparison unit that compares signal levels of a plurality of signals and reduce the amount of electric current for a period other than this comparison period. For example, the amount of electric current may be reduced by turning off part of a group of switches each capable of disconnecting a path of an electric current from an electric current source. In addition, for example, the amount of electric current may be reduced by causing a gate potential at the electric current source unit to decrease. The present technology can be applied to, for example, an image pickup element and an electronic appliance.