RC-Timed VCO Locking for Symmetric High-Frequency CAN Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems face challenges in generating symmetrical high-frequency timing signals for Controller Area Network (CAN) communications, leading to undesired electromagnetic radiation due to voltage spikes and phase differences, which are difficult to manage with conventional VCO circuits at frequencies above 100 MHz.
Innovation Solution
The implementation of a timing circuit that locks a voltage-controlled oscillator (VCO) to high frequencies using a digital filter and adjustable current converter, with a digital-to-analog converter and logic control circuit to adjust the center frequency of the high-frequency signal, ensuring minimal interruption and energy dissipation through a dummy load, thereby reducing electromagnetic radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional VCO circuits are used to generate high-frequency timing signals above 100 MHz, then the timing signal frequency can be increased, but voltage spikes and phase differences occur leading to undesired electromagnetic radiation
Solution Approach 1:
The patent employs a phase detector that continuously monitors the phase difference between the VCO output and a reference signal, generating an error signal that feeds back to the VCO control input. This feedback mechanism automatically corrects phase deviations and prevents voltage spikes, thereby eliminating electromagnetic radiation while maintaining high-frequency operation
Solution Approach 2:
The patent introduces a low-pass filter as an intermediary between the phase detector and VCO control input. This filter smooths the error signal to remove high-frequency components that could cause voltage spikes, acting as a mediator that protects the VCO from generating harmful electromagnetic radiation while allowing precise frequency control
2Stability of the object's composition
If external oscillators or phased-lock loops are used to generate high-frequency timing signals, then frequency stability can be improved, but device complexity increases
Solution Approach 1:
The patent merges the frequency multiplication function and phase locking function into a single integrated circuit block. The VCO is directly controlled by a phase-locked loop that operates at the final high frequency, eliminating the need for separate external oscillators and intermediate frequency stages, thereby achieving frequency stability without increasing overall device complexity
Solution Approach 2:
The patent designs a universal phase-locked loop controller that can lock the VCO to any desired high-frequency reference signal. This multi-functional controller handles both frequency synthesis and phase stabilization in one unit, replacing multiple specialized components and reducing overall system complexity while maintaining frequency stability
3Device complexity
If lower frequency timing signals are used, then device complexity is reduced, but signal symmetry deteriorates leading to increased electromagnetic radiation
Solution Approach 1:
The patent employs dynamic phase adjustment within the phase-locked loop that continuously adapts to maintain signal symmetry at high frequencies. The control circuit dynamically modifies the VCO input to compensate for any asymmetry that develops, ensuring symmetrical differential signals without requiring complex static circuit design
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 effectively generates symmetrical high-frequency timing signals, reducing electromagnetic radiation and enabling efficient data transmission without significant spikes, thus improving data integrity and reducing electromagnetic interference in CAN communications.
Implementation Method 1
an RC timer operable to generate a time signal
Implementation Method 2
a voltage controlled oscillator (VCO) operable, when in an "ON" state, to receive the control signal and output a high frequency signal
Data Source
AI summary
Circuits and processes for locking a voltage-controlled oscillator (VCO) at a high frequency signal are described. A circuit may include an adjustable current converter (ACC), coupled at an input terminal to a power source, operable to output a control signal (VC) at an output terminal. A first switch may be coupled to the ACC and to the VCO. The VCO, when in an “ON” state, receives the control signal and outputs a high frequency signal (VHF). A digital filter may be coupled to the VCO and operable to receive the VHF. Based on the VHF, the digital filter generates a data signal having a data value. The circuit may also include a digital-to-analog converter (DAC) operable to receive the data signal and, based on the data value, output an adjustment signal to the ACC. The ACC may adjust the control signal based on the adjustment signal received from the DAC.