Voltage Converter Back Gate Control for Transistor Variation
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Solution Overview
Problem
Conventional voltage converter circuits experience variations in transistor electrical characteristics due to current flowing through the back channel, leading to increased off-state current and power consumption, especially when the clock signal is stopped.
Innovation Solution
Applying a potential generated by the voltage converter circuit to the back gate of the transistor within the voltage conversion block to control the current through the back channel, using transistors with low off-state current to maintain output potential stability even when the clock signal is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional voltage converter circuit is used with transistors having floating back gates, then the circuit structure is simple, but the electrical characteristics of the transistor vary due to current flowing through the back channel, leading to increased off-state current and power consumption
Solution Approach 1:
The transistor is divided into two gates: a front gate and a back gate. The back gate is separated and connected to a dedicated potential generation circuit, allowing independent control of the back channel potential. This segmentation enables precise control of the back channel current, reducing off-state current and power consumption while maintaining simple overall circuit structure.
Solution Approach 2:
A potential generation circuit is introduced as an intermediary component between the power source and the back gate. This intermediary circuit generates and supplies the appropriate potential to the back gate, mediating the control of back channel current and enabling reduced off-state current without complicating the main voltage converter circuit structure.
2Device complexity
If the back gate is left in a floating state to simplify the circuit, then the device complexity is reduced, but the electrical characteristics vary due to drain potential affecting back channel current
Solution Approach 1:
The gate structure is segmented into front gate and back gate, with the back gate independently controlled by a potential generation circuit. This allows the back channel potential to be stabilized separately from the main switching operation, preventing electrical characteristic variations while keeping the overall circuit relatively simple.
Solution Approach 2:
The potential of the back gate is changed and controlled independently from the front gate potential. By dynamically adjusting the back gate potential through the potential generation circuit, the electrical characteristics are stabilized against variations caused by drain potential, while maintaining circuit simplicity.
3Loss of energy
If a negative potential is continuously applied to the gate to reduce off-state current, then the off-state current is reduced, but power consumption increases
Solution Approach 1:
The gate control is segmented into front gate (for switching) and back gate (for off-state current control). The back gate receives a negative potential from the potential generation circuit to suppress off-state current, while the front gate handles switching operations. This segmentation allows off-state current reduction without continuous power consumption for maintaining the negative potential during active operation.
Solution Approach 2:
The potential generation circuit provides negative potential to the back gate in a periodic or controlled manner rather than continuously. The back gate potential is adjusted based on operational requirements, reducing off-state current when needed while minimizing power consumption during active switching phases.
Data Source
AI summary
To reduce a variation in the electrical characteristics of a transistor. A potential generated by a voltage converter circuit is applied to a back gate of a transistor included in a voltage conversion block. Since the back gate of the transistor is not in a floating state, a current flowing through the back channel can be controlled so as to reduce a variation in the electrical characteristics of the transistor. Further, a transistor with low off-state current is used as the transistor included in the voltage conversion block, whereby storage of the output potential is controlled.