Comparator Voltage Measurement With Offset Compensation
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Solution Overview
Problem
Existing methods for measuring internal supply voltage in integrated circuits face challenges due to voltage drops and variations caused by process and temperature changes, leading to inaccurate voltage readings across different integrated circuit dies and over time.
Innovation Solution
A circuit comprising a comparator, resistor divider, multiplexer, and programmable gain amplifier is used to measure and compensate for internal supply voltage, employing a band gap reference voltage generator to maintain reference voltages constant across process, supply voltage, and temperature variations, and a finite state machine to select appropriate reference voltages and generate compensation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple voltage measurement method is used, then the device complexity is reduced, but the measurement precision deteriorates due to voltage drops and process variations
Solution Approach 1:
The patent applies parameter changes by using a programmable gain amplifier to dynamically adjust the gain parameter based on the measured voltage level. The gain is programmed to be inversely proportional to the internal supply voltage, which compensates for voltage drops and process variations. This allows the measurement circuit to maintain high precision across different operating conditions without requiring a completely complex measurement architecture.
Solution Approach 2:
The patent implements feedback by using the measured internal supply voltage to control the gain of the programmable gain amplifier. The measurement result feeds back to adjust the amplification factor, creating a closed-loop system that automatically compensates for voltage variations. This feedback mechanism enables accurate measurements despite changes in supply voltage, temperature, or manufacturing process parameters.
2Measurement precision
If compensation for offset voltage is added, then the measurement precision is improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent applies self-service by making the programmable gain amplifier automatically adjust its own gain parameter based on the measured voltage. The amplifier uses the measurement result to program its gain, eliminating the need for external offset compensation circuits or additional adjustment components. This self-programming capability provides precision compensation while minimizing additional circuit complexity.
3Reliability
If the measurement circuit is made more robust against temperature and process variations, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent uses parameter changes to achieve robustness against temperature and process variations. By dynamically programming the gain parameter of the amplifier based on the measured voltage, the circuit adapts to different operating conditions without requiring multiple fixed-gain amplifiers or complex temperature compensation networks. This single adjustable parameter approach maintains reliability across conditions while keeping the architecture simple.
Data Source
AI summary
A circuit includes a comparator, a resistor divider, a control circuit, a multiplexer, and a programmable gain amplifier. The comparator is operable to measure an internal voltage of the circuit based on a selected reference voltage. The resistor divider is operable to generate reference voltages. The control circuit is operable to generate a select signal based on an output signal of the comparator. The multiplexer is operable to select one of the reference voltages from the resistor divider as the selected reference voltage based on the select signal. The programmable gain amplifier is configurable to generate a compensation voltage to compensate for an offset voltage of the comparator. The compensation voltage is provided to an input of the comparator.