VCO Power Supply AGC Using Peak Detection for Tolerance Compensation
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Solution Overview
Problem
Existing power supplies for voltage-controlled oscillators (VCOs) struggle to compensate for variations in performance due to component tolerances, leading to missed performance specifications during mass production, as they cannot accurately mirror the behavior of oscillating circuits, causing interference and incomplete compensation.
Innovation Solution
An oscillator system with a voltage-controlled oscillator (VCO), a peak detector, a reference generator, and a gain control circuit that adjusts the input voltage based on the amplitude of the VCO's output waveform, using a closed-loop automatic gain control (AGC) loop to maintain optimal operation within specified ranges, eliminating the need for error integrators and ensuring fast start-up capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a duplicate circuit of the VCO's active components is used to mirror the behavior of the VCO, then the power supply can be adjusted based on component variations, but the approach cannot fully compensate for variation since the VCO is oscillating and has Q factor characteristics that vary with tolerances
Solution Approach 1:
The patent uses a duplicate circuit (copy circuit) that mirrors the VCO's active components to model and compensate for process variations. The copy circuit generates a copy of the VCO signal that is used to control the power supply voltage, enabling dynamic compensation without requiring a physical duplicate oscillating circuit that would cause interference.
Solution Approach 2:
The patent implements a feedback mechanism where the VCO output signal is fed back through the copy circuit to continuously adjust the power supply voltage. This closed-loop feedback ensures that the power supply dynamically compensates for variations in real-time, maintaining optimal VCO performance despite component tolerances.
2Measurement precision
If a duplicate oscillating circuit is created to mirror the behavior of the VCO, then compensation for variations can be achieved, but the frequency of the duplicate circuit would interfere with the frequency of the VCO itself, causing spurs
Solution Approach 1:
The patent creates a copy of the VCO signal through a duplicate active circuit rather than a full oscillating circuit. This copy is used to control the power supply without generating interfering frequencies, as it operates in the baseband rather than at the VCO frequency.
Solution Approach 2:
The patent separates the compensation function from the oscillation function. The duplicate circuit only replicates the active components for compensation purposes, while the actual oscillation occurs only in the VCO. This segmentation prevents frequency interference while maintaining compensation accuracy.
3Device complexity
If traditional power supply circuits are used for VCOs, then the design is simple, but they cannot compensate for variations due to component tolerances, causing the VCO to miss performance specifications
Solution Approach 1:
The patent introduces a copy circuit that duplicates the VCO's active components to sense process variations. This additional copying element enables automatic compensation for component tolerances, ensuring the VCO meets performance specifications across production variations.
Solution Approach 2:
The patent implements a feedback loop that continuously monitors the VCO output and adjusts the power supply voltage accordingly. This feedback mechanism automatically compensates for component variations, maintaining performance compliance without requiring complex manual calibration or trimming.
Data Source
AI summary
The disclosure relates to technology for power supply for a voltage controller oscillator (VCO). A peak detector circuit determines the amplitude of the output for the VCO, which is compared to a reference value in an automatic gain control loop. An input voltage for the VCO is determined based on a difference between the reference value and the output of the peak detector circuit. The peak detector circuit can be implemented using parasitic bipolar devices in an integrated circuit formed in a CMOS process.