Voltage Conversion Circuit Glitch Noise Reduction
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Solution Overview
Problem
In voltage conversion circuits for solid-state imaging elements, low power source voltage can cause pMOS transistors to remain in an OFF state, leading to signal propagation issues and increased noise due to glitches, which are difficult to suppress without increasing power consumption.
Innovation Solution
A voltage conversion circuit configuration that includes a conversion transistor, a current source transistor, and a control circuit to stop current supply when the input signal potential changes, using a pMOS transistor with lower breakdown voltage and an nMOS transistor, and employing a NOR gate to control current flow and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two stages of inverters are used for voltage conversion, then voltage conversion is achieved, but power consumption increases due to through current when signals are inverted
Solution Approach 1:
The patent applies dynamics by making the current supply controllable and variable rather than constant. The current source transistor is controlled to supply current only when needed (during voltage conversion) and stop when the signal stabilizes, converting a static current consumption pattern into a dynamic one that adapts to signal state changes.
Solution Approach 2:
The patent implements feedback by monitoring the output signal state and using it to control the current source transistor. When the output signal stabilizes at a certain voltage level, this state is fed back to turn off the current supply, creating a closed-loop control system that automatically adjusts power consumption based on signal conditions.
2Use of energy by moving object
If low-voltage power source is used, then power consumption is reduced, but pMOS transistor cannot turn on properly when gate-source voltage is below threshold voltage
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the current supplied to the pMOS transistor based on the signal state. During voltage conversion, increased current is supplied to ensure proper transistor switching even at low voltages, while during stable states, current is reduced or stopped to minimize power consumption.
Solution Approach 2:
The patent implements preliminary action by proactively controlling the current supply in anticipation of signal transitions. The current source transistor is activated before or during voltage conversion operations to ensure reliable transistor switching, and deactivated when conversion is complete, preventing both failure to switch and unnecessary power consumption.
3Object-generated harmful factors
If source-grounded circuit with nMOS transistor and resistor is used instead of inverter, then glitch is suppressed, but current regularly flows from power source increasing power consumption
Solution Approach 1:
The patent applies dynamics by making the current supply controllable and variable rather than constant. The current source transistor is controlled to supply current only when needed (during voltage conversion) and stop when the signal stabilizes, converting a static current consumption pattern into a dynamic one that adapts to signal state changes.
Solution Approach 2:
The patent implements periodic action by supplying current in discrete intervals rather than continuously. Current is supplied during voltage conversion periods and stopped during stable signal periods, creating a periodic on-off pattern that reduces average power consumption while maintaining glitch suppression during active conversion phases.
Data Source
AI summary
Noise is reduced in a circuit that converts voltage. A voltage conversion circuit includes a conversion transistor, a current source transistor, and a control circuit. In this voltage conversion circuit, the conversion transistor converts a potential of an input signal, the potential being changed from one of two different potentials to the other, by using predetermined current, and outputs the converted signal as an output signal. Furthermore, the current source transistor supplies the predetermined current. Then, in a case where the potential of the input signal is changed to the other potential, the control circuit stops supplying the predetermined current.