VCO Gain Calibration Using Two-Stage Frequency Correction
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Solution Overview
Problem
Voltage-controlled oscillators (VCOs) suffer from unstable gain due to manufacturing process variations, leading to ±10% differences between circuits, affecting their performance.
Innovation Solution
A voltage control oscillating apparatus with a two-stage gain calibration mechanism, involving a first calibration circuit to adjust the control current and a second calibration circuit to adjust the conversion parameter, stabilizing the output frequency by iteratively correcting frequency differences until they fall within predetermined values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage-controlled oscillator is implemented by converting control voltage to current, then the oscillator can generate clock signals with required frequency, but the gain becomes unstable due to manufacturing process variation causing ±10% difference between circuits
Solution Approach 1:
The patent applies preliminary action by performing a two-stage calibration process before normal operation. The first calibration circuit calibrates the control current at a first control voltage to compensate for manufacturing variations. The second calibration circuit then calibrates the conversion parameter at a second control voltage. This preliminary calibration ensures that the VCO gain remains stable despite ±10% manufacturing variations in the voltage-to-current conversion circuit.
2Reliability
If manufacturing process variation is reduced to improve gain stability, then circuit performance becomes more consistent, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies self-service by designing automatic calibration circuits that perform gain calibration without external intervention. The first calibration circuit automatically adjusts the control current based on frequency feedback, and the second calibration circuit automatically adjusts the conversion parameter. This self-calibrating mechanism compensates for manufacturing variations without requiring manual adjustment or complex external testing equipment.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the control current and conversion parameter during calibration. The first calibration circuit changes the control current parameter to compensate for manufacturing variations. The second calibration circuit then changes the conversion parameter (transconductance) to optimize performance at a different control voltage. These parameter adjustments enable the VCO to maintain stable gain across process variations.
3Measurement precision
If calibration processes are added to correct frequency differences, then output frequency accuracy improves, but circuit complexity and calibration time increase
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into two distinct stages. The first calibration circuit handles coarse calibration by adjusting the control current at a first control voltage to achieve initial frequency accuracy. The second calibration circuit then performs fine calibration by adjusting the conversion parameter at a second control voltage. This segmented approach achieves high frequency accuracy while keeping each calibration stage relatively simple and fast.
Data Source
AI summary
The present disclosure discloses a voltage control oscillating apparatus having gain calibration mechanism. A voltage control oscillating circuit converts a control voltage to a control current to generate an output clock signal having an output frequency. A first calibration circuit controls the voltage control oscillating circuit to perform a first calibration process that includes setting the control voltage as a first voltage, determining a first frequency difference between the output frequency and a first target frequency and adjusting the control current accordingly to approximate the output frequency to the first target frequency. A second calibration circuit controls the voltage control oscillating circuit to perform a second calibration process that includes setting the control voltage as a second voltage, determining a second frequency difference between the output frequency and a second target frequency and adjusting the control current accordingly to approximate the output frequency to the second target frequency.