VCO Calibration Circuit for Stable Frequency and Lower Complexity
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Solution Overview
Problem
Conventional voltage-controlled oscillator (VCO) frequency synthesizers are complex and costly, with difficulty in designing and manufacturing due to multiple control units, which complicates the adjustment of oscillation frequency.
Innovation Solution
A calibration circuit for VCO that employs a two-stage adjustment method, using a calibration bias generator, detection unit, micro control unit, phase-locked loop (PLL) unit, control voltage detection unit, and control switch set to adjust oscillation frequency within a predetermined range by comparing control voltages, simplifying the circuit complexity while maintaining frequency adjustment functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional frequency synthesizer with multiple control units is used, then oscillation frequency can be adjusted, but circuit complexity increases and manufacturing cost increases
Solution Approach 1:
The patent combines multiple control units into a single integrated calibration circuit that performs both open-loop frequency calibration and closed-loop control voltage calibration. The calibration circuit includes a calibration bias generator, detection unit, micro control unit, adjuster unit, and control switch set that work together to replace the functionality of separate control units, thereby reducing circuit complexity while maintaining frequency adjustment capability.
Solution Approach 2:
The calibration circuit is designed to perform multiple functions: it calibrates oscillation frequency in open-loop mode and calibrates control voltage in closed-loop mode. The micro control unit coordinates both calibration processes, and the adjuster unit can adjust both the oscillation frequency and control voltage, making the circuit universal and reducing the need for separate specialized control units.
2Adaptability or versatility
If conventional frequency synthesizer with multiple control units is used, then oscillation frequency can be adjusted, but manufacturing cost increases
Solution Approach 1:
By merging multiple control units into a single calibration circuit with shared components (micro control unit, adjuster unit, detection unit), the patent reduces the total component count and simplifies the manufacturing process. This integration directly lowers manufacturing costs while preserving the frequency adjustment capability.
3Adaptability or versatility
If conventional frequency synthesizer with multiple control units is used, then oscillation frequency can be adjusted, but design difficulty increases
Solution Approach 1:
The patent integrates multiple control functions into a unified calibration circuit architecture, reducing the number of interfaces and interactions that need to be designed and coordinated. The micro control unit centralizes the control logic, simplifying the overall design process while maintaining the ability to adjust oscillation frequency.
4Measurement precision
If open-loop calibration is used, then oscillation frequency can be adjusted within predetermined range, but control voltage may be outside predetermined range
Solution Approach 1:
The patent performs open-loop frequency calibration first to establish the oscillation frequency within the predetermined range, then performs closed-loop control voltage calibration to adjust the control voltage to its predetermined range. This preliminary action sequence ensures both frequency accuracy and voltage stability are achieved systematically.
Solution Approach 2:
The patent implements closed-loop control voltage calibration where the detection unit monitors the control voltage and the micro control unit adjusts the calibration bias generator accordingly. This feedback mechanism ensures the control voltage is adjusted to fall within the predetermined range, resolving the issue of voltage instability that would result from open-loop calibration alone.
Data Source
AI summary
A calibration circuit for voltage-controlled oscillator (VCO) includes a calibration bias generator, a VCO, a detection unit, a micro control unit, an adjuster unit, a phase-locked loop (PLL) unit, a control voltage detection unit, and a control switch set. The calibration bias generator outputs a first control voltage. The VCO outputs an oscillation frequency according to the first control voltage. The detection unit detects the oscillation frequency and outputs the detection result signal to the micro control unit. The micro control unit outputs an adjust signal according to the detection result signal. The adjuster unit receives the adjust signal voltage and adjusts the oscillation frequency output from the VCO according to the adjust signal voltage. The PLL unit outputs a second control voltage to the VCO. The control voltage detection unit outputs voltage-detection signal to the micro control unit, which outputs the adjust signal according to the voltage-detection signal.