Peak Voltage Measurement Using Clamping and Timer Circuits
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Solution Overview
Problem
Conventional circuitry for measuring peak voltage of high AC signals exceeds cost, area, and power requirements due to the need for expensive analog-to-digital converters and temperature-sensitive resistor dividers, which are not suitable for high voltage inputs.
Innovation Solution
A peak voltage detection circuit that uses a clamping circuit to constrain AC voltage within safe input levels, coupled with comparators and a timer circuit to determine the time interval between voltage thresholds, estimating peak voltage through slew rate calculation without requiring rectifiers or expensive ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional circuitry with ADC converters and resistor dividers is used to measure peak voltage of high AC signals, then measurement capability is achieved, but cost, circuit area, and power consumption increase significantly
Solution Approach 1:
The patent extracts only the essential function needed for peak voltage measurement - detecting when the AC signal exceeds positive and negative thresholds - and eliminates unnecessary components such as ADC converters, rectifiers, and complex sampling logic. The solution uses simple comparators to detect threshold crossings and a timer to measure the time interval, achieving peak voltage measurement with minimal circuitry.
Solution Approach 2:
The patent replaces expensive, precision-critical components with inexpensive alternatives. Instead of using expensive ADC converters and precision resistor dividers that require temperature compensation, the invention uses cheap comparators with fixed threshold voltages and a simple timer circuit. The measurement approach sacrifices continuous precision for sufficient accuracy in determining whether peak voltage exceeds a threshold.
2Measurement precision
If ADC converters and precision resistor dividers are used for high voltage measurement, then accurate voltage values are obtained, but circuit board area and component cost increase
Solution Approach 1:
The patent removes the ADC converter and precision resistor divider from the circuit, keeping only the essential threshold detection and timing functions. This extraction reduces the circuit board area significantly while maintaining sufficient measurement capability for determining whether peak voltage exceeds a specified threshold.
Solution Approach 2:
Instead of directly measuring the high voltage signal with expensive precision components, the patent creates a simplified copy of the measurement function using comparators that generate digital output signals based on threshold crossings. This copied function achieves the same practical purpose (determining if voltage exceeds threshold) with minimal hardware.
3Reliability
If resistor dividers with temperature compensation are used for high voltage measurement, then measurement reliability over temperature range is improved, but cost and circuit complexity increase
Solution Approach 1:
The patent eliminates the temperature compensation circuitry entirely by using comparators with fixed, stable threshold voltages that are inherently less sensitive to temperature variations than resistor divider ratios. The simple timing-based measurement approach does not require precision resistance values, thus removing the need for temperature compensation.
Solution Approach 2:
The patent replaces expensive temperature-stable resistors and compensation circuits with inexpensive comparators and a timer. The measurement system achieves sufficient reliability for threshold detection without requiring high-precision components that are sensitive to temperature.
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 solution reduces costs, area, and power consumption while maintaining accuracy, enabling efficient peak voltage measurement for AC signals exceeding the maximum input voltage of measurement circuits.
Implementation Method 1
a clamping circuit coupled to the input terminal, the clamping circuit configured to output a clamped voltage signal that is constrained between a positive voltage magnitude and a negative voltage magnitude
Implementation Method 2
a first comparator coupled to the clamped voltage signal configured to output a first compare signal when the voltage signal is a positive voltage that exceeds a positive threshold reference voltage; and a second comparator coupled to the clamped output signal configured to output a second compare signal when the output voltage signal is a negative voltage that exceeds a negative threshold reference voltage
Implementation Method 3
a timer circuit coupled to the first compare signal and to the second compare signal and coupled to a clock signal, configured to output a time duration output signal corresponding to a time interval between the first and second compare signals
Data Source
AI summary
In described examples, an apparatus includes: an input terminal for receiving an alternating current voltage signal; a clamping circuit coupled to the input terminal outputting a clamped voltage signal that is constrained in magnitude; a first comparator coupled to the clamped voltage signal outputting a first compare signal when the clamped voltage signal is a positive voltage that exceeds a positive threshold; and a second comparator coupled to the clamped voltage signal outputting a second compare signal when the clamped voltage signal is a negative voltage that exceeds a negative threshold. The apparatus includes a timer circuit coupled to the first and second compare signal outputting a time duration signal corresponding to a time between the first and second compare signals; and a logic circuit coupled to the time duration output signal determining a peak voltage of the alternative current voltage signal responsive to the time duration output signal.