Feedback-Controlled Level Shift Circuit for Low-Power High-Speed Switching
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Solution Overview
Problem
Existing level shift circuits face challenges in converting low-amplitude input signals to high-amplitude output signals efficiently, leading to slowed operations and increased power dissipation due to transient short circuit currents and larger circuit areas, especially when dealing with high-voltage differences between power supply voltages.
Innovation Solution
A level shift circuit configuration that includes a first and second level shifter connected between different power supply terminals and an output terminal, with a feedback control unit controlling the switching of complementary signals to deactivate at least one level shifter during specific time intervals, thereby preventing short circuit currents and optimizing the level shift operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the level shift circuit uses conventional charging and discharging elements to convert low-amplitude signals to high-amplitude signals, then the signal conversion function is achieved, but transient short circuit currents occur and power dissipation increases
Solution Approach 1:
The patent applies dynamics by making the circuit configuration changeable over time through the switching element. The switching element dynamically reconfigures the circuit between different states: in the first state, the charging element charges the capacitor; in the second state, the discharging element discharges the capacitor. This dynamic reconfiguration prevents transient short circuit currents while maintaining efficient level shifting operation, resolving the contradiction between energy loss and operational efficiency.
Solution Approach 2:
The patent implements periodic action through the alternating charging and discharging cycles of the capacitor. The switching element periodically transitions between the first and second states, creating a rhythmic pattern of charge accumulation and discharge. This periodic operation allows the circuit to efficiently convert low-amplitude signals to high-amplitude signals without generating harmful transient currents, thereby reducing power dissipation while maintaining productivity.
2Reliability
If the level shift circuit increases the number of circuit elements to handle high voltage differences, then the voltage conversion capability is improved, but the circuit area increases
Solution Approach 1:
The patent applies merging by combining multiple functions into a single integrated circuit structure. The switching element simultaneously controls both the charging and discharging paths, while the single capacitor serves both as the energy storage element and the output coupling element. This consolidation achieves high voltage conversion capability without proportionally increasing circuit area, as the shared components reduce the total element count compared to conventional separate charging and discharging circuits.
Solution Approach 2:
The patent implements multi-functionality where the switching element serves multiple purposes: it acts as a gate for the charging element, a gate for the discharging element, and a controller for the overall circuit operation. The capacitor also serves dual functions as both the energy storage device and the output signal generator. This universal design allows the circuit to handle high voltage differences effectively while minimizing the area occupied by circuit elements.
3Speed
If the level shift circuit uses larger element sizes to increase discharging capability, then the signal conversion speed is improved, but the circuit area increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor to the high voltage level before the discharge phase begins. The switching element first establishes the charged state with the charging element, ensuring that when the discharge phase starts, the capacitor is already prepared with the necessary energy. This preliminary charging action enables fast signal conversion without requiring oversized discharging elements, as the energy is already stored and ready for immediate release, thereby maintaining high speed while minimizing circuit area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables high-speed level shifting with lower power dissipation and area savings, allowing for efficient conversion of low-amplitude input signals to high-amplitude outputs without generating transient short circuit currents, even at high voltage differences.
Implementation Method 1
P-channel MOS transistors P1 and P2 which have sources connected to a power supply terminal VDD3, have gates connected to output terminals W2 and W1, respectively, and have drains connected to the output terminals W1 and W2, respectively. The P-channel MOS transistors P1 and P2 function as charging elements for the output terminals W1 and W2, respectively.
Data Source
AI summary
Disclosed is a level shift circuit that includes a first level shifter which is connected between an output terminal and a first power supply terminal that supplies a first voltage and sets the output terminal to a level of the first voltage when an input signal received at an input terminal assumes a first value; a second level shifter which is connected between the output terminal and a second power supply terminal that supplies a second voltage and sets the output terminal to a level of the second voltage when the input signal assumes a complementary value of the first value; and a feedback control unit that performs control of deactivating the first level shifter during a predetermined time interval including a point of time when the input signal is supplied when it is detected that the output terminal immediately before the input signal is received at the input terminal assumes the first voltage level. When the input signal supplied in the predetermined time interval assumes a value that sets the output terminal to the second voltage level, the second level shifter sets the output terminal to the second voltage level with the first level shifter deactivated.