Address Detector Circuit Using DAC Current Comparison
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Solution Overview
Problem
Existing analog to digital address detector circuits face limitations in precision due to the tolerance of external resistors, which restricts the address range and accuracy in programming device characteristics.
Innovation Solution
An integrated circuit incorporating a comparator circuit, counter, and digital to analog converters that dynamically adjust current and voltage to accurately set device characteristics by comparing voltages across an external resistor, allowing for tighter tolerance and increased address range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant current source and ADC are used to read voltage drop across an external resistor, then the address can be detected, but the precision is limited by the external resistor tolerance
Solution Approach 1:
The patent changes the measurement parameter from voltage (V=IR) to current by using a digital-to-analog converter to generate a current that is compared with the current through the external resistor. This transformation allows the measurement to be independent of the resistor's tolerance, as the comparison is made between two currents where one is digitally controlled and the other flows through the external resistor.
Solution Approach 2:
The patent replaces the traditional voltage measurement system (ADC measuring voltage drop) with a current comparison system using a comparator circuit. This substitution eliminates the need to accurately measure voltage across a tolerance-prone resistor, instead using a digital counter and DAC to generate a comparable current that can be precisely matched against the resistor current.
2Adaptability or versatility
If external resistors with standard tolerance are used for programming device addresses, then the address range is limited, but using tighter tolerance resistors increases cost and complexity
Solution Approach 1:
The system uses the external resistor itself as part of the addressing mechanism rather than requiring it to be a precision component. The resistor's value (within its tolerance range) directly contributes to the address code, and the comparator-based detection method automatically adapts to the actual resistor value, eliminating the need for tight tolerance manufacturing.
Solution Approach 2:
The patent changes how the resistor parameter is utilized - instead of requiring the resistor to have a precise fixed value for accurate voltage measurement, the system uses the resistor's actual value (within tolerance) to define the address range, with the digital counter and comparator adapting to match the current through whatever resistor value is present.
3Adaptability or versatility
If a comparator circuit with counter and DAC is used to detect address, then the address range increases four times, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into an integrated detector circuit that includes the comparator, counter, and digital-to-analog converter working together as a unified system. This merging allows the circuit to perform current comparison, counting, and voltage generation in a coordinated manner, achieving four times the address range while managing complexity through functional integration.
4Measurement precision
If the counter increments to increase current and decrease voltage until voltage transition, then the measurement accuracy improves, but the time to complete the detection increases
Solution Approach 1:
The counter increments in periodic steps, with each increment adjusting the DAC output current and allowing the comparator to evaluate the condition. This periodic action continues until the voltage transition condition is met, providing a systematic approach that balances precision with reasonable detection time by using discrete counting steps rather than continuous adjustment.
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 enhances the address range by four times, achieving tighter resistor tolerance and improved accuracy in programming device characteristics compared to traditional circuits.
Implementation Method 1
The comparator receives a second voltage based on the first current and a value of an external resistance. The comparator enables the counter and latches a counter value when the first voltage transitions to a value less than a second voltage input to the comparator.
Implementation Method 2
A digital to analog converter receives an inverse of the digital counter value of the counter and generates a first voltage.
Implementation Method 3
A variable current source receives the digital counter value of the counter and generates a first current. The variable current source includes a second digital to analog converter.
Implementation Method 4
The comparator receives a second voltage based on the first current and a value of an external resistance.
Data Source
AI summary
An analog to digital detector circuit includes a comparator circuit and a counter that generates a digital counter value. A digital to analog converter receives an inverse of the digital counter value of the counter and generates a first voltage. A variable current source receives the digital counter value of the counter and generates a first current.