Crystal Oscillator Current Control for EMI-Robust Low Power Clocks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low power oscillators are sensitive to electromagnetic interference (EMI), leading to performance degradation, frequency shifts, and prolonged recovery times, which can disrupt electronic labels used in environments with other electronic systems.
Innovation Solution
An oscillator circuit arrangement with a digital clock signal monitor circuit that detects frequency shifts and loss of oscillation, generating a control signal to increase current through the gain stage, using a digital control loop to boost current and enhance transconductance, thereby improving robustness against EMI and reducing recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the oscillator is designed for low power consumption, then power usage is reduced, but sensitivity to electromagnetic interference increases and recovery time is prolonged
Solution Approach 1:
The patent implements a feedback mechanism where a monitor circuit detects oscillation conditions and controls the current through the gain stage. When oscillation is detected or frequency shift is identified, the control signal adjusts the current to maintain robust operation against EMI while preserving low power consumption characteristics.
Solution Approach 2:
The oscillator employs dynamic current control where the current through the gain stage is adjusted based on real-time oscillation detection. The system transitions between different current states depending on whether oscillation is present or a frequency shift is detected, optimizing both power consumption and EMI robustness dynamically.
2Use of energy by moving object
If the oscillator is designed for low power consumption, then power usage is reduced, but recovery time after EMI event is prolonged
Solution Approach 1:
The monitor circuit continuously monitors oscillation conditions in advance, detecting frequency shifts or loss of oscillation before they fully disrupt operation. This preliminary detection allows the system to prepare for recovery by adjusting current levels proactively, reducing the actual recovery time while maintaining low power consumption during normal operation.
Solution Approach 2:
The feedback loop provides real-time information about oscillation status to the control circuit, enabling rapid response to EMI events. When oscillation is lost or frequency shifts occur, the feedback mechanism triggers current adjustment to accelerate recovery, balancing fast recovery with low power consumption requirements.
3Reliability
If the current through the gain stage is increased to improve EMI robustness, then robustness against EMI is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the current through the gain stage based on oscillation detection. During normal operation, low current is maintained for minimal power consumption. When EMI events are detected through the monitor circuit, the current is temporarily increased to maintain robustness, then reduced again when normal operation resumes, optimizing the balance between reliability and power usage.
Solution Approach 2:
The patent changes the current parameter through the gain stage based on oscillation conditions. The control signal modifies the current level dynamically - increasing it when frequency shifts or oscillation loss are detected to improve EMI robustness, and maintaining it at lower levels during normal operation to preserve ultra-low power consumption characteristics.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~5
AI summary
An oscillator circuit arrangement comprises a gain stage (10) and a feedback loop that includes a crystal device (XC). A clock signal monitor circuit (12) is connected to an output (102) of the gain stage and detects a frequency shift in the clock signal or a loss of oscillation. The current through the gain stage is controlled in response to a control signal generated by the clock signal monitor circuit.