VCO Bias Circuit Stability via Direct Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bias circuits for voltage-controlled oscillators (VCOs) face issues with stability and oscillation range due to the need for voltage-to-current conversion, which can result in circuit malfunction and accuracy errors when the control voltage is below the threshold, and introduces gain errors affecting the VCO's stability.
Innovation Solution
A bias circuit that eliminates the need for a voltage-to-current converter by using a voltage-controlled current source and a delay control circuit, directly applying control voltage to the delay unit, thereby generating a bias current and improving stability without gain errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage-to-current converter is used to convert control voltage Vc into current I, then the bias circuit can generate the required current for the delay unit, but when Vc is lower than the threshold, the input tube cannot be turned on and the entire circuit cannot work normally
Solution Approach 1:
The patent extracts and removes the voltage-to-current converter from the circuit. Instead of converting Vc to current I through a separate converter circuit, the control voltage Vc is directly applied to the delay unit, which eliminates the threshold problem and expands the usable control voltage range.
Solution Approach 2:
The delay unit is designed to accept control voltage directly without requiring conversion to current. This multi-functional approach allows the same component to handle both the timing function and the voltage control function, eliminating the need for a separate voltage-to-current converter and improving reliability across the full voltage range.
2Measurement precision
If the control voltage Vc is converted into current I and then into temporary voltage V through multiple conversion stages, then the bias circuit can control the delay unit, but grain errors are introduced during conversion processes, affecting the accuracy of the VCR resistance and influencing VCO stability
Solution Approach 1:
The patent removes the intermediate conversion stages that cause grain errors. By eliminating the voltage-to-current converter and the subsequent current-to-voltage conversion, the direct voltage control path preserves signal integrity and prevents accuracy degradation.
Solution Approach 2:
The patent eliminates the need for intermediary conversion circuits. The control voltage Vc directly controls the delay unit without passing through intermediate current conversion stages, thereby avoiding the accumulation of conversion errors and maintaining high precision throughout the control chain.
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 solution enhances the stability and oscillation range of the VCO by eliminating the need for a voltage-to-current converter, ensuring the circuit operates normally across a wider range of control voltages and maintaining accuracy.
Implementation Method 1
a voltage-controlled current source, having a voltage control terminal connected to a voltage output terminal of the error amplifier circuit, in which a current generated thereby is controlled by a voltage at the voltage output terminal of the error amplifier circuit
Data Source
AI summary
A bias circuit and a voltage-controlled oscillator (VCO) thereof suitable for improving the stability of the bias circuit are provided. The bias circuit includes: an error amplifier circuit, having an inverting input terminal connected to a reference voltage; a voltage-controlled current source, having a voltage control terminal connected to a voltage output terminal of the error amplifier circuit, in which a current generated by the current source is controlled by a voltage at the voltage output terminal of the error amplifier circuit; a delay control circuit, having a current input terminal connected to the voltage-controlled current source, an output terminal connected to a non-inverting input terminal of the error amplifier circuit, and a voltage input terminal connected to a supply terminal of the control voltage, and the delay control circuit is adapted to adjust an output voltage of the delay control circuit according to a control voltage.