Single-Input Voltage Level Shifter Without DC Leakage
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Solution Overview
Problem
Conventional voltage level shifter circuits face challenges in shifting signals from a low voltage domain to a high voltage domain without creating a direct current leakage path, which consumes excessive power and requires dual rail inputs, making them inefficient in routing-limited designs.
Innovation Solution
A voltage level shifter circuit design using a first and second inverter circuit, a first NMOS transistor, a first PMOS transistor, and a second PMOS transistor, which receives a power down signal to disable direct current leakage paths, allowing signal shifting with a single input and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional voltage level shifter circuit is used to shift signals from low voltage domain to high voltage domain, then voltage level shifting is achieved, but a direct current leakage path is created between VDDH and ground, consuming excessive power
Solution Approach 1:
The circuit dynamically controls the activation of transistors based on the input signal state. When input is low, transistors 115 and 130 are activated to discharge output to ground. When input is high, transistor 130 turns off and transistor 110 activates to charge the output node through capacitor 145, preventing continuous current flow and eliminating the direct current leakage path while maintaining voltage level shifting capability
Solution Approach 2:
Capacitor 145 serves as an intermediary energy storage element that couples the low voltage domain to the high voltage domain. It stores charge during the charging phase and discharges it during the output phase, enabling voltage level shifting without creating a direct current path between VDDH and ground, thus resolving the contradiction between power consumption and shifting capability
2Device complexity
If a dual rail input level shifter circuit is used to reduce power consumption, then direct current leakage is eliminated, but the number of inputs and routing wires is doubled
Solution Approach 1:
The circuit achieves multi-functionality by using a single input that can drive the voltage level shifter in both charging and discharging modes. The same input signal controls both the charging path (through transistor 110 and capacitor 145) and the discharging path (through transistors 115 and 130), eliminating the need for separate complementary inputs while maintaining low power operation
Solution Approach 2:
The circuit merges the charging and discharging control functions into a single input signal. Instead of requiring separate input and input_b signals, the single input controls the activation of transistor pairs that perform both charging (via 110, 145) and discharging (via 115, 130) operations, reducing routing complexity while preventing direct current leakage
Data Source
AI summary
One embodiment of the present invention sets forth a technique for shifting the voltage level of signals from a low voltage domain to a high voltage domain, where VDDH is the supply voltage of the high voltage domain and VDDL is the supply voltage of the low voltage domain. A level shifting circuit uses a single input rather than dual rail inputs and does not produce a direct current flow in order to reduce the power consumption. The voltage level shifting circuit may also be used to shift a clock signal since the delays of the rising and falling edges of the clock signal are matched by using a delay element.