Level Shift Circuit Precharge to Prevent Through-Current
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Solution Overview
Problem
Existing level shift circuits experience increased power consumption due to through currents when transitioning between binary logic states, particularly in circuits with p-channel transistors.
Innovation Solution
A level shift circuit design that includes a voltage applying part, an input part, and a switching part, where a predetermined voltage is applied intermittently to a first node, and a reference voltage is applied to a second node only when the input signal is at a specific voltage level, with the switching part connecting and disconnecting the nodes based on the voltage application, and an inverter providing a phase-inverted output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor changes state from OFF to ON during signal level transition, then the signal level shifts correctly, but through current flows causing increased power consumption
Solution Approach 1:
The circuit applies a predetermined voltage to the first node in advance (pre-charging) before the actual signal transition occurs. This preliminary voltage application ensures that when the transistor switches, there is no voltage difference across it, preventing through-current flow while maintaining correct signal level shifting.
Solution Approach 2:
The voltage applying part operates intermittently rather than continuously, applying predetermined voltage only during specific periods when needed for signal level shifting. This periodic operation reduces overall power consumption by eliminating continuous voltage application that would cause sustained through-currents.
2Reliability
If transistors are set in ON state complementarily to shift signal levels, then level shifting is achieved, but unwanted power consumption increases due to through current
Solution Approach 1:
The circuit pre-charges the first node with a predetermined voltage before the input signal causes transistor switching. This preliminary voltage application eliminates the voltage differential that would otherwise cause through-current during transitions, reducing energy loss while preserving the level shifting function.
Solution Approach 2:
The invention converts what would normally be harmful through-currents into beneficial pre-charging current. By intentionally applying predetermined voltage to charge the node before signal transitions, the circuit transforms potential energy waste into a useful function that actually reduces overall power consumption by preventing larger discharge currents during switching.
Data Source
AI summary
A level shift circuit which comprises a voltage applying part configured to apply predetermined voltage to a first node intermittently. An input part receives an input signal and applies reference voltage to a second node when a signal level of the input signal is equal to a first voltage level. A switching part connects the second node and the first node with each other during the voltage applying part does not apply the predetermined voltage to the first node. The switching part cuts off the connection between the second node and the first node during the voltage applying part applies the predetermined voltage to the first node. An inverter provides a phase-inverted signal of the signal given to the first node as an output signal.