Closed-Loop VCO ADC Linearization for Accurate Temperature Sensing
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Solution Overview
Problem
Modern very large scale integration (VLSI) chipsets face challenges in accurate temperature sensing due to the nonlinearity of voltage-controlled oscillators (VCOs), which requires additional circuitry to address, and the limited number of sensors on ICs due to size constraints, impacting thermal management and power consumption.
Innovation Solution
Implementing closed loop linearized VCO-based analog-to-digital converters (ADCs) that include a first amplifier, a voltage-controlled oscillator, a switched-capacitor resistor, and a counter to generate a digital output proportional to the input voltage, addressing the inverse proportionality of VCO-based ADCs and providing a more reliable temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If VCO-based ADC is used for temperature sensing, then power consumption is reduced and integration is simplified, but nonlinearity in frequency response degrades measurement precision
Solution Approach 1:
The patent implements a closed-loop feedback system where the VCO output frequency is fed back through a switched-capacitor resistor to the amplifier input. This feedback mechanism automatically linearizes the transfer function by compensating for VCO nonlinearity, eliminating the need for external calibration circuits while maintaining low power consumption and high integration density.
Solution Approach 2:
The patent transforms the nonlinear VCO frequency-voltage relationship into a linear input-output characteristic by dynamically adjusting the switched-capacitor resistor values based on the operating point. This parameter adaptation allows the system to maintain measurement precision across varying temperature ranges without increasing power consumption.
2Measurement precision
If additional circuitry is added to linearize VCO response, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the linearization function directly into the existing VCO feedback path by utilizing the switched-capacitor resistor network that is already part of the amplifier circuitry. This integration approach achieves precise temperature measurement without adding separate linearization circuits, thereby avoiding increased device complexity.
Solution Approach 2:
The switched-capacitor resistor serves multiple functions simultaneously: it provides feedback for amplifier operation, enables automatic linearization of the VCO response, and facilitates low-power operation. This multi-functionality eliminates the need for dedicated linearization components, maintaining circuit simplicity while achieving high measurement precision.
3Reliability
If more sensors are implemented across IC, then thermal management coverage is improved, but IC size constraints are violated
Solution Approach 1:
The VCO-based ADC circuit performs multiple functions within a single integrated block: it serves as both the temperature sensor interface and the analog-to-digital converter for the entire IC. This multi-functional design enables comprehensive thermal monitoring across the chip without requiring multiple discrete sensor components, thus adhering to strict size constraints while improving thermal management reliability.
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 provides a linear and accurate temperature measurement, eliminating nonlinearity issues and enabling efficient thermal management and reduced power consumption across ICs.
Implementation Method 1
a first voltage-controlled oscillator (VCO) operably coupled to the first amplifier and configured to output a first signal based on the first control signal, the first signal having a sensor frequency
Data Source
AI summary
A device and method for analog to digital conversion is disclosed. The device can have a first amplifier operable to receive an input voltage and output a first control signal. The device can also have a first voltage-controlled oscillator (VCO) operably coupled to the first amplifier and configured to output a first signal based on the first control signal, the first signal having a sensor frequency. The device can also have a first switched-capacitor resistor operably coupled to the first VCO and to the first amplifier, the first switched-capacitor resistor configured to receive and be controlled by the sensor frequency. The device can also have a sensor counter operably coupled to the first VCO and configured produce a sensor count based on the sensor frequency. The device can also have a register configured provide a digital output proportional to the input voltage based on the sensor count.