Current-Mirror Level Shifting for Accurate High-Voltage Comparison
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Solution Overview
Problem
Existing high voltage comparator and operational amplifier circuits face challenges in accurately operating with high input and reference voltages, as prior solutions amplify noise and do not allow for voltage level shifting, particularly when dealing with high voltage MOS transistors above 3.3V.
Innovation Solution
A level shifting circuit comprising a current mirror and two level shifters with resistors, along with overvoltage protectors, to generate bias currents and apply voltage variations, enabling the circuit to operate within a typical CMOS range and provide overvoltage protection, allowing for accurate monitoring and comparison of high voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a divider is applied to set input and reference voltage into typical CMOS operable range, then the voltage level is reduced to acceptable range, but the random offset noise is amplified and voltage level shift is not possible
Solution Approach 1:
The circuit is divided into multiple independent modules: overvoltage protection module, level shifting module, and current mirror module. Each module performs a specific function - the overvoltage protection module protects against high voltage, the level shifting module shifts voltage levels without amplifying noise, and the current mirror module provides accurate current copying. This segmentation allows each module to optimize its function without compromising overall performance.
Solution Approach 2:
The patent introduces an intermediary level shifting circuit between the high voltage input and the CMOS comparator. This intermediary circuit uses resistors and current mirrors to transfer voltage information from high voltage domain to low voltage domain without direct coupling, thereby avoiding noise amplification while enabling voltage level transition.
2Adaptability or versatility
If high voltage comparator is designed to operate with high input voltages, then high voltage monitoring capability is achieved, but noise suppression and accuracy are compromised
Solution Approach 1:
The patent transitions from direct high voltage comparison to indirect comparison through voltage level shifting. Instead of comparing high voltages directly in the high voltage domain, the circuit shifts both input voltages to the low voltage domain and then compares them. This dimensional transition from high voltage domain to low voltage domain enables accurate comparison while maintaining high voltage monitoring capability.
Solution Approach 2:
The current mirror circuit copies the current from the input side to the output side with high accuracy. By copying the current information rather than directly transmitting high voltage signals, the circuit maintains signal integrity and accuracy while operating in high voltage environment. The current mirror ensures that the copied current accurately represents the original input signal.
3Measurement precision
If external high voltage MOS transistors are monitored via drain to source voltages, then current monitoring capability is achieved, but the high voltage signals require special handling
Solution Approach 1:
The comparator circuit is designed with universal functionality to handle both high voltage and low voltage signals. The same comparator can monitor currents of different types of external high voltage MOS transistors by simply connecting its inputs to the drain-to-source voltage nodes. The overvoltage protection and level shifting modules automatically handle the high voltage signals, making the circuit universally applicable without requiring different designs for different voltage levels.
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
The solution achieves high accuracy and a wide adjustable threshold range for integrated circuits under high voltage applications, reduces noise, and minimizes the silicon chip area required, effectively supporting the monitoring of high voltage MOS transistors while suppressing input noise.
Implementation Method 1
a current mirror for generating a first bias current and a second bias current proportional to the first bias current with a first ratio
Implementation Method 2
the first level shifter is configured to apply a first voltage variation to the first input signal in response to the first bias current... the first level shifter comprises a first resistor coupled between the first input node and the first output node
Data Source
AI summary
A level shifting circuit includes a current mirror that generates a first bias current and a second bias current (proportional to the first bias current with a first ratio). A first level shifter is coupled between a first input node (receiving a first input signal) and a first output node coupled to an input of the current mirror. The first level shifter applies a first voltage variation to the first input signal in response to the first bias current. A second level is coupled between a second input node (receiving a second input signal) and a second output node coupled to an output of the current mirror. The second level shifter applies a second voltage variation (associated with the first voltage variation) to the second input signal in response to the second bias current.