Cross-Coupled Oscillator Supply Tuning for Frequency Compensation
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Solution Overview
Problem
Conventional phase-locked loops require a large number of varactors for frequency compensation, which deteriorate oscillator performance and increase design complexity and area occupancy.
Innovation Solution
An oscillator design that uses a power supply circuit with a first cross-coupled transistor and a resonant circuit, where the oscillation frequency is compensated by adjusting a power supply signal generated from a combination of fixed and variable voltages, eliminating the need for numerous varactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large quantity of varactors are disposed inside the VCO/DCO for frequency compensation, then the frequency compensation range is widened, but the phase noise and spur performance deteriorate and the occupied area increases
Solution Approach 1:
The patent changes the parameter being controlled for frequency compensation from the resonant frequency (via varactors) to the power supply voltage/current of the cross-coupled transistor. By adjusting the power supply signal parameters, the oscillation frequency is compensated without degrading phase noise and spur performance, thus resolving the contradiction between compensation range and performance.
2Adaptability or versatility
If a large quantity of varactors are disposed inside the VCO/DCO for frequency compensation, then the frequency compensation range is widened, but the occupied area increases
Solution Approach 1:
The patent transitions from controlling oscillation frequency through varactor capacitance changes (requiring large area) to controlling it through power supply signal adjustments. This parameter change approach achieves frequency compensation with minimal additional circuit area, as the power supply circuit can be implemented with compact components.
3Adaptability or versatility
If a large quantity of varactors are disposed inside the VCO/DCO for frequency compensation, then the frequency compensation range is widened, but the design difficulty increases
Solution Approach 1:
The patent simplifies the design by changing the control mechanism from complex varactor networks to a straightforward power supply signal adjustment. The power supply circuit with adjustable voltage/current is inherently simpler to design and implement than a large array of varactors, reducing design difficulty while maintaining compensation effectiveness.
Data Source
AI summary
Example oscillators and oscillator-based apparatus are described. One example oscillator includes: a resonant circuit, configured to generate an oscillator signal; a first cross-coupled transistor, coupled to the resonant circuit; and a power supply circuit, configured to supply a power supply signal for the first cross-coupled transistor based on a first voltage and a second voltage, where the first voltage is a power supply voltage, and the second voltage is a voltage generated by an external sensing circuit. Because an oscillation frequency of the oscillator changes with the power supply signal of the oscillator, the oscillation frequency of the oscillator can be compensated by adjusting the power supply signal.