Oscillation Circuit Switching Layout for Stable Resonator Frequency
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Solution Overview
Problem
Existing oscillators with metal oxide semiconductor (MOS) transistors face instability in oscillation frequency due to signal leakage when the oscillation signal swings below ground level or reaches the power supply level, affecting the MOS transistor's conductivity and resulting in unstable oscillation frequencies.
Innovation Solution
The oscillation circuit incorporates a configuration with N-channel and P-channel MOS switches that control the coupling of external connection terminals and a node, allowing for two modes: one where the voltage at the node is fixed to ground, stabilizing the frequency, and another where the switches couple terminals for inspection and drive level testing, reducing signal leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oscillator is set to the second mode during normal operation to allow signal input at the external connection terminal, then the resonator can be inspected through overdrive and drive level tests, but the oscillation signal may leak to the external connection terminal when it swings below ground level or reaches power supply level, causing unstable oscillation frequency
Solution Approach 1:
The patent divides the coupling control into multiple independent switching elements (first switching element for coupling external connection terminal to first node, second switching element for coupling first node to second external connection terminal, third switching element for coupling external connection terminal to second external connection terminal). This segmentation allows precise control of signal paths, enabling the oscillator to maintain stable frequency during normal operation while allowing inspection modes without signal leakage.
Solution Approach 2:
The patent implements dynamic switching between different operational modes (first mode for normal operation with fixed node voltage, second mode for inspection with coupled terminals). The switching elements dynamically adjust the electrical coupling state based on operational requirements, allowing the system to transition between stability-prioritized mode and inspection-prioritized mode without compromising oscillation frequency stability during normal operation.
2Adaptability or versatility
If the MOS transistor is used for switching between first mode and second mode, then the oscillator can accommodate inspection functions in a small, low-profile, single package, but the MOS transistor becomes weakly conductive when the oscillation signal swings below ground level or reaches power supply level, causing signal leakage
Solution Approach 1:
The patent introduces an intermediate node (first node) between the external connection terminal and the oscillation circuit. This intermediate node serves as a buffer zone that prevents direct coupling between the external terminal and the oscillation signal path during normal operation. The switching elements control coupling to this intermediate node, allowing inspection signals to be applied without directly affecting the oscillation signal and causing leakage.
Solution Approach 2:
The patent uses dynamic switching control to change the operational state of the oscillator. In the first mode, switching elements are configured to fix the voltage at the first node, preventing signal leakage. In the second mode, switching elements are configured to couple terminals for inspection. This dynamic reconfiguration allows the same hardware to serve both stable operation and inspection functions without signal leakage in normal mode.
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
This configuration stabilizes the oscillation frequency by fixing the node voltage in normal operation and allowing signal propagation for inspection modes, reducing frequency fluctuations and enabling effective overdrive and drive level inspections.
Implementation Method 1
a first switching element that switches whether or not to electrically couple the first external connection terminal and the first node, and a second switching element that switches whether or not to electrically couple the first node and the second external connection terminal
Implementation Method 2
an amplification circuit that is electrically coupled to the second external connection terminal and the third external connection terminal, amplifies a signal output from the resonator, and supplies the amplified signal to the resonator
Implementation Method 3
a resonator, an amplification circuit that is electrically coupled to the second external connection terminal and the third external connection terminal, amplifies a signal output from the resonator
Data Source
AI summary
An oscillation circuit includes a first node, a first switching element, and a second switching element and has a first mode in which the first switching element does not electrically couple the first external connection terminal and the first node and the second switching element does not electrically couple the first node and the second external connection terminal which is electrically coupled to one end of a resonator and a second mode in which the first switching element electrically couples the first external connection terminal and the first node and the second switching element electrically couples the first node and the second external connection terminal, and in the first mode, a voltage of the first node is fixed.