Capacitor-Coupled Level Shifter With Stable Boosting
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Solution Overview
Problem
Conventional level shifters require a dedicated power supply, leading to increased space and load on external circuits, and suffer from degraded boosting characteristics due to depletion characteristics in transistors with diode connections.
Innovation Solution
A level shifter configuration that includes an input terminal, a first capacitor, and two transistors with a signal generating unit to control the second transistor's conduction state, eliminating the need for a dedicated power supply and preventing degradation in boosting characteristics by avoiding diode connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated power supply is provided for level shifting, then the level shifter can provide stable voltage conversion, but the space required increases and the load on external circuits increases
Solution Approach 1:
The patent combines the power supply function with the signal processing function by using the input signal itself as the power source. The circuit merges the voltage conversion operation with the existing signal path, eliminating the need for separate power supply lines while maintaining stable voltage conversion through the capacitor coupling mechanism
Solution Approach 2:
The input signal serves multiple functions simultaneously: it acts as both the signal to be processed and the power source for the level shifting operation. The capacitor C1 serves dual purposes as both a coupling element and an energy storage element that enables voltage boosting without external power supply
2Device complexity
If diode connection of transistor is used for level shifting, then the circuit structure is simplified, but leakage current is generated when transistor has depletion characteristics, degrading boosting characteristics
Solution Approach 1:
Instead of using diode connection which forces the transistor into a specific operating mode that causes leakage with depletion characteristics, the patent inverts the approach by using the transistor in a standard switch configuration controlled by a separately generated signal. This reverses the problem by avoiding the diode connection constraint entirely
Solution Approach 2:
The patent introduces an intermediary signal generating unit that produces the control signal for the second transistor, mediating between the input signal and the transistor operation. This intermediary mechanism allows the transistor to operate in its optimal switching mode without the harmful effects of diode connection, maintaining boosting characteristics while keeping the circuit relatively simple
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 reduces the need for a dedicated power supply, minimizes space and load on external circuits, and maintains effective boosting characteristics even with transistors having depletion characteristics.
Implementation Method 1
a first capacitor; a first transistor having a source electrode and a drain electrode that are provided between an input terminal and one electrode of the first capacitor
Data Source
AI summary
A level shifter includes: an input terminal to which an input voltage is applied; a capacitor; a first transistor provided between the input terminal and one of electrodes of the capacitor, and having a gate electrode connected to the other of the electrodes of the capacitor; a second transistor provided between the input terminal and the other electrode of the capacitor; a signal generating unit which generates a signal for switching the second transistor between conduction and non-conduction and supply the signal to the gate electrode of the second transistor, in a period when the input voltage is provided to the input terminal; and an output terminal for outputting a voltage at the other electrode of the capacitor which is level-shifted by a change in the second transistor to a non-conducting state in the period as an output voltage.