Comparator-Based Slew Rate Detection for IC Mismatch Compensation
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Solution Overview
Problem
Existing techniques for detecting the slew rate of integrated circuits are inadequate, as they either only characterize mismatches at a single point on the current-voltage curve or require significant space and manual calculations, making them unsuitable for automatic mismatch compensation.
Innovation Solution
A method involving a first and second comparator, an exclusive OR gate, and an integrator to generate an output pulse with a pulse width indicative of the slew rate, which is then integrated over time to produce an output voltage proportional to the slew rate, enabling detection of device mismatches and automatic mismatch compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple ring oscillators are used to detect slew rate, then measurement precision is improved, but device complexity and space requirements increase significantly
Solution Approach 1:
The measurement range is segmented into multiple ranges with different gains (first gain for first range, second gain for second range). The circuit automatically selects appropriate gain segments based on the input signal amplitude, allowing accurate measurement across wide slew rate ranges without requiring multiple complete oscillator circuits.
Solution Approach 2:
The circuit changes the gain parameter dynamically based on the input signal range. By switching between first and second gain values corresponding to first and second ranges, the system maintains measurement precision across different slew rate magnitudes while using a single integrated circuit structure.
2Measurement precision
If manual calculation of device mismatch parameters is required, then measurement precision may be maintained, but ease of operation and automation are reduced
Solution Approach 1:
The circuit provides automatic feedback by generating output signals that directly represent the device mismatch parameters. The slew rate detector and gain controller work together to automatically calculate and output mismatch information without requiring manual intervention, thereby improving ease of operation while maintaining measurement precision.
Solution Approach 2:
The system performs self-measurement and self-calculation of device mismatch parameters. The integrated circuit automatically processes the input signal, determines the slew rate, calculates mismatch parameters, and generates output signals representing these parameters, eliminating the need for external manual calculation.
3Power
If high current gain is designed to provide large open loop gain, then amplification capability is improved, but susceptibility to saturation and slew rate limitations increases
Solution Approach 1:
The circuit dynamically adjusts the gain based on the input signal characteristics. By switching between different gain values (first gain and second gain) corresponding to different input ranges, the system maintains high open-loop gain when needed while preventing saturation by reducing gain when the signal approaches saturation levels, thereby improving slew rate capability.
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 effectively determines rising and falling slews, providing an output voltage indicative of the slew rate, allowing for the estimation of semiconductor device mismatches and enabling compensation to improve microprocessor yield.
Implementation Method 1
a first comparator for comparing the signal with a first reference voltage
Implementation Method 2
a second comparator for comparing the signal with a second reference voltage different from the first reference voltage
Implementation Method 3
an exclusive OR (XOR) gate operatively coupled to the first and second comparators for generating an output pulse having a pulse width indicative of a slew rate of the signal
Implementation Method 4
an integrator for integrating the output pulse over time to generate an output voltage proportional to the pulse width
Data Source
AI summary
Determining a slew rate of a signal from an integrated circuit under test by comparing the signal with a first reference voltage, comparing the signal with a second reference voltage different from the first reference voltage, generating an output pulse having a pulse width indicative of a slew rate of the signal, and integrating the output pulse over time to generate an output voltage proportional to the pulse width; wherein the output voltage is indicative of the slew rate of the signal produced by the integrated circuit.