Level Shift Circuit for High Common Mode Voltage Conversion
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Solution Overview
Problem
Existing voltage monitoring and measurement systems face challenges in accurately converting differential voltage signals with high common mode voltage components to ground referenced signals, leading to errors and high costs due to extensive calibration requirements.
Innovation Solution
A circuit that includes a comparator-based front end with a feedback loop controlling a 2nd order sigma delta ADC, where the level shift signal is generated in the low voltage domain, reducing the need for high voltage domain reference signals and minimizing calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional high voltage domain conversion circuits are used to convert differential voltage signals with high common mode voltage to ground referenced signals, then voltage measurement can be achieved, but the circuit complexity increases and extensive calibration is required
Solution Approach 1:
The patent introduces an intermediary low voltage domain level shift circuit that mediates between the high voltage differential signal and the ground referenced measurement circuit. This intermediary circuit converts the high common mode voltage signal to a low voltage signal before further processing, eliminating the need for complex high voltage domain reference signals and reducing calibration requirements.
Solution Approach 2:
The conversion process is segmented into distinct stages: first, the high voltage differential signal is converted to a low voltage single-ended signal via the level shift circuit; second, the low voltage signal is processed by the ADC; third, the digital output is converted back to analog form. This segmentation allows each stage to be optimized independently, reducing overall system complexity.
2Measurement precision
If extensive calibration procedures are implemented to compensate for offset, gain and linearity errors, then measurement accuracy improves, but testing costs increase significantly
Solution Approach 1:
The level shift circuit is designed to inherently provide accurate level conversion without requiring external calibration procedures. By using a straightforward voltage translation approach with fixed reference voltages, the circuit serves itself by maintaining accuracy through its design rather than through post-manufacturing calibration, significantly reducing testing costs.
3Measurement precision
If high voltage domain reference signals are generated to maintain signal integrity during conversion, then measurement accuracy is preserved, but the circuit size and complexity increase
Solution Approach 1:
Instead of converting the signal in the high voltage domain and then referencing it to ground, the patent inverts the approach by first translating the high voltage signal to the low voltage domain and then performing ground referenced measurement. This inversion eliminates the need for high voltage reference signals entirely, reducing circuit area while maintaining measurement integrity.
Data Source
AI summary
A system, circuit and method for converting a differential voltage signal including a high common mode voltage component to a ground referenced signal are disclosed. For example, a circuit for converting a differential voltage signal including a high common mode voltage component to a ground referenced signal is disclosed. The circuit includes a comparator configured to receive a differential voltage signal including a high common mode voltage component, and output a digital signal associated with the differential voltage signal. The circuit also includes a level shifter configured to receive the digital signal and shift the level of the digital signal to a low level, and an integrator configured to receive the digital low level signal and output a ramping voltage associated with the low level signal. Furthermore, the circuit includes an analog-to-digital converter configured to receive the ramping voltage and output a digital bit-stream associated with the ramping voltage.