Oscillation Circuit Duty Cycle Calibration Under Gate Leakage
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Solution Overview
Problem
Advanced semiconductor manufacturing processes lead to significant gate leakages in transistors, causing duty cycle deviations in quartz oscillation signals, which existing frequency doublers struggle to calibrate effectively without increasing circuit complexity and noise.
Innovation Solution
An oscillation circuit with an amplifier, feedback resistor, and a switch circuit that conducts between the input and output terminals based on voltage thresholds to stabilize the duty cycle, using a switch circuit with an on-state resistance smaller than the feedback resistor to mitigate leakage current effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frequency doubler is used to calibrate the duty cycle, then the duty cycle calibration capability is improved, but the circuit area increases and more noises are introduced
Solution Approach 1:
The patent extracts the duty cycle calibration function from the complex frequency doubler circuit and implements it using a simple switch circuit that selectively connects or disconnects the feedback resistor. This extraction principle allows the calibration capability to be achieved without the unnecessary complexity and noise of a full frequency doubler implementation.
Solution Approach 2:
The patent changes the resistance parameter of the feedback path by switching the feedback resistor in and out of the circuit. By controlling the switch state, the feedback resistance is dynamically adjusted to compensate for gate leakage effects and maintain 50% duty cycle, achieving calibration through parameter modification rather than complex circuitry.
2Speed
If transistors are miniaturized to achieve high-speed and high-frequency circuits, then the circuit speed and frequency are improved, but gate leakage increases causing duty cycle deviation
Solution Approach 1:
The patent implements a feedback mechanism where the switch circuit monitors the effect of gate leakage on the duty cycle and dynamically adjusts the feedback resistor connection to compensate. This feedback loop maintains the duty cycle at 50% despite the increased gate leakage from miniaturized transistors, resolving the reliability issue while preserving the high-speed performance.
Solution Approach 2:
The switch circuit automatically detects and compensates for the gate leakage effects without requiring external intervention or complex calibration procedures. The circuit self-adjusts by controlling the feedback resistor connection based on the operating conditions, maintaining duty cycle stability autonomously.
Data Source
AI summary
An oscillation circuit including an amplifier, a feedback resistor and a first switch circuit is provided. The amplifier inverts and amplifies an oscillation signal received from an input terminal thereof to provide an output oscillation signal at an output terminal thereof. The feedback resistor is coupled between the input terminal and the output terminal, and coupled with the first switch circuit in parallel. The first switch circuit conducts the input terminal to the output terminal in one of the following situations: (1) an input voltage of the oscillation signal is higher than an output voltage of the output oscillation signal by at least a first threshold value; and (2) the output voltage is higher than the input voltage by at least a second threshold value. The first switch circuit has a first on-state resistance smaller than a resistance of the feedback resistor.