Sensor Interface Circuit With VCO Frequency Synchronization for Low Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensor interface circuits face challenges in reducing current consumption, power consumption, size, and cost due to the use of original oscillators like crystal oscillators or resonators, which also increase lock time and are not suitable for IoT applications.
Innovation Solution
A frequency synchronization circuit is implemented in the sensor interface circuit that performs frequency synchronization in the voltage domain without using an original oscillator, utilizing a reference voltage source, current source, voltage difference detection circuit, voltage-controlled oscillation circuit, and frequency/impedance conversion circuit to achieve high accuracy and reduce current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an original oscillator such as crystal is used to convert a signal of a sensor into frequency with high accuracy, then measurement precision is improved, but current consumption increases
Solution Approach 1:
The patent extracts the oscillation function from a traditional crystal oscillator and implements it using a voltage-controlled oscillation circuit (VCO) that can be selectively activated. This allows the system to achieve frequency conversion without continuously powering an original oscillator, thereby reducing current consumption while maintaining measurement precision when oscillation is actually needed.
Solution Approach 2:
The patent employs a dynamic approach by using a VCO whose oscillation frequency can be controlled by a control voltage. This dynamic circuit can be turned on and off as needed, and its frequency can be adjusted based on sensor input, providing both accuracy and power efficiency compared to a static crystal oscillator that must continuously operate.
2Measurement precision
If an original oscillator such as crystal is used to convert a signal of a sensor into frequency with high accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The voltage-controlled oscillation circuit serves multiple functions: it generates the oscillation signal, converts the sensor signal to frequency, and can be controlled to operate only when needed. This multi-functional approach replaces the need for separate crystal oscillator circuits, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the operating parameters from a fixed-frequency crystal oscillator to a variable-frequency VCO controlled by voltage. This parameter change allows the circuit to adapt its frequency based on sensor input and to be disabled when not needed, simplifying the overall system architecture while preserving accuracy requirements.
3Use of energy by moving object
If a voltage-controlled oscillation circuit is used instead of an original oscillator, then current consumption is reduced, but lock time increases
Solution Approach 1:
The patent implements preliminary action by providing a start signal that pre-configures the VCO before actual oscillation begins. This start signal prepares the voltage-controlled oscillation circuit in advance, reducing the time needed for the circuit to stabilize and lock onto the correct frequency, thereby addressing the lock time issue while maintaining power savings.
4Ease of manufacture
If a frequency synchronization circuit is implemented without an original oscillator, then cost is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent creates a functional copy of the oscillator function using a VCO instead of a physical crystal oscillator. This copied function achieves the same frequency conversion purpose through voltage control, eliminating the need for expensive crystal components while maintaining the necessary measurement precision through proper circuit design and control.
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 allows for reduced current consumption, meets power consumption and size requirements for IoT technology, and lowers implementation costs by eliminating the need for original oscillators, while maintaining high accuracy and stability.
Implementation Method 1
a voltage-controlled oscillation circuit connected to the output node of the voltage difference detection circuit, the voltage-controlled oscillation circuit being configured to generate an oscillation signal according to the control voltage
Implementation Method 2
a frequency/impedance conversion circuit connected between the voltage-controlled oscillation circuit and the second input node of the voltage difference detection circuit, the frequency/impedance conversion circuit being configured to convert a frequency of a signal according to the oscillation signal into impedance
Data Source
AI summary
A sensor interface circuit includes a frequency synchronization circuit connectable to a sensor. The frequency synchronization circuit includes: a reference voltage source generating a reference voltage; a current source connected to the reference voltage source, and generating a current by using the reference voltage; a voltage difference detection circuit including first and second input nodes and an output node, generating a control voltage according to a difference between voltages received at the first and second input nodes, one of the voltages received at the first and second input nodes corresponding to a detection value of the sensor; a voltage-controlled oscillation circuit connected to the output node, and generating an oscillation signal according to the control voltage; and a frequency/impedance conversion circuit connected between the voltage-controlled oscillation circuit and the second input node, and converting a frequency of a signal according to the oscillation signal into impedance.