Oscillator Control Circuit for Wider Tuning Range and Lower Jitter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Voltage-controlled oscillators in integrated circuits face sensitivity issues due to small operating voltage ranges, leading to unwanted jitter, which requires large filtering capacitors in phase-locked loops, increasing costs.
Innovation Solution
A control signal generating circuit that uses any voltage level between a supply voltage source and ground to control oscillating signal generating devices, employing a combination of P-type and N-type field effect transistors to monotonically generate current-controlled signals, allowing for a larger controllable voltage range and reduced jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the operating voltage range of the integrated circuit is reduced to decrease size, then the integrated circuit size is reduced, but the control voltage range becomes smaller causing the voltage-controlled oscillator to become very sensitive to control voltage and induce unwanted jitter
Solution Approach 1:
The patent introduces a control signal generating circuit as an intermediary between the control voltage input and the voltage-controlled oscillator. This circuit converts the control voltage into a current signal that linearly controls the oscillation frequency, thereby mediating the sensitivity issue and preventing jitter while maintaining the reduced voltage range operation
Solution Approach 2:
The patent changes the control parameter from voltage to current. By using a current-controlled oscillator instead of a voltage-controlled oscillator, the system achieves linear frequency control with respect to the control parameter, eliminating the sensitivity and jitter problems associated with reduced voltage ranges
2Productivity
If the gain (Kvco) of the voltage-controlled oscillator is increased to maintain frequency range with smaller voltage range, then the frequency range is maintained, but the oscillator becomes very sensitive to control voltage inducing unwanted jitter
Solution Approach 1:
The patent changes the control parameter from voltage to current, transforming the oscillator into a current-controlled device. This parameter change provides linear frequency control with respect to the control parameter, maintaining the required frequency range while eliminating the sensitivity and jitter issues caused by high voltage gain
3Reliability
If a large filtering capacitor is used in the loop filter to filter out induced jitter, then the jitter is filtered out, but the cost of the phase-locked loop becomes higher
Solution Approach 1:
The patent converts the harmful jitter effect into a benefit by using the current control mechanism to prevent jitter generation in the first place. The monotonic current control inherently suppresses jitter, transforming the problem of jitter filtering into a preventive control solution that eliminates the need for expensive large capacitors
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
The solution enables a larger frequency range in oscillating circuits with reduced jitter, allowing for smaller filtering capacitors in phase-locked loops, thereby decreasing manufacturing costs.
Implementation Method 1
the first transconducting circuit is arranged to generate a first current signal according to a voltage input signal
Implementation Method 2
the second transconducting circuit is arranged to generate a third current signal according to the voltage input signal
Implementation Method 3
The current mirror is coupled to the current adjusting circuit and the second transconducting circuit, and arranged to generate a current controlled signal according to at least one of the second current signal and the third current signal
Data Source
AI summary
An oscillating signal generating device includes: an oscillating circuit arranged to generate an oscillating signal according to a current controlled signal; and a control signal generating circuit coupled to the oscillating circuit, the control signal generating circuit for receiving a first reference voltage and a second reference voltage, the control signal generating circuit operated between the first reference voltage and the second reference voltage, and the control signal generating circuit arranged to generate the current controlled signal according to a voltage input signal; wherein the control signal generating circuit is capable of monotonically generating the current controlled signal according to the voltage input signal when a voltage level of the voltage input signal falls between the first reference voltage and the second reference voltage.