Programmable Oscillator Supply Regulator for PLL Frequency Re-Centering
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Solution Overview
Problem
Phase-locked loops (PLLs) in integrated circuits face challenges in maintaining a stable frequency range and phase noise performance due to imperfect modeling of inductors, parasitic components, and variations in process, supply voltage, and temperature (PVT), which can cause the center frequency and frequency range of output clock signals to shift outside design specifications.
Innovation Solution
A programmable regulator is used to generate a regulated supply voltage that adjusts the frequency range of the oscillator, allowing the PLL to re-center the center frequency and maintain the output frequency range within specifications without adding a second tuning knob, thereby compensating for shifts caused by PVT variations and parasitic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed supply voltage is used for the oscillator, then the circuit design is simple, but the frequency range shifts outside specifications due to PVT variations and parasitic components
Solution Approach 1:
The patent implements a programmable regulator that dynamically adjusts the supply voltage to the oscillator based on detected frequency range deviations. Instead of using a fixed voltage, the system continuously monitors output frequency and modifies the supply voltage accordingly, transforming a static design into an adaptive one that compensates for PVT variations and parasitic effects.
Solution Approach 2:
The patent changes the supply voltage parameter to the oscillator to compensate for frequency shifts. By varying the voltage supplied to the oscillator, the system adjusts the frequency range back into specification, directly addressing the instability caused by process, voltage, and temperature variations.
2Reliability
If the supply voltage to the oscillator is changed to adjust frequency range, then the frequency range stability improves, but phase noise performance deteriorates
Solution Approach 1:
The patent employs a feedback mechanism where the output frequency of the PLL is detected and compared against the desired frequency range. Based on this feedback, the programmable regulator adjusts the supply voltage to the oscillator, creating a closed-loop control system that stabilizes frequency range while minimizing unnecessary voltage changes that would increase phase noise.
Solution Approach 2:
The system uses its own output frequency signal to regulate its input supply voltage. The PLL output is fed back to control the regulator, which in turn controls the oscillator supply, creating a self-regulating system that automatically corrects frequency deviations without external intervention.
3Reliability
If a programmable regulator is added to adjust frequency range, then frequency range stability improves, but device complexity increases
Solution Approach 1:
The programmable regulator is designed to serve multiple functions: it provides the primary supply voltage to the oscillator, adjusts frequency range deviations, and works in conjunction with the existing PLL feedback mechanism. By integrating these functions into a single component, the patent reduces overall system complexity despite adding regulation capability.
Solution Approach 2:
The programmable regulator acts as an intermediary component between the fixed voltage source and the oscillator. It provides a buffer that allows frequency adjustment without directly modifying the oscillator design, isolating the complexity in a dedicated regulation stage rather than dispersing it throughout the entire circuit.
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 programmable regulator effectively re-centers the frequency range and reduces phase noise, enabling the PLL to generate high-frequency output clock signals while maintaining a wide frequency range, thus addressing the instability issues in PLLs fabricated in programmable logic integrated circuits.
Implementation Method 1
The programmable regulator generates a regulated supply voltage using an input voltage and changes the regulated supply voltage from a first voltage to a second voltage in response to a first control signal. The first and the second voltages are generated using charge from the input voltage.
Data Source
AI summary
A circuit comprises a programmable voltage regulator and an oscillator. The programmable regulator generates a regulated supply voltage using an input voltage and changes the regulated supply voltage from a first voltage to a second voltage in response to a first control signal. The first and the second voltages are generated using charge from the input voltage. The regulated supply voltage drives the oscillator. The oscillator varies a frequency of a periodic output signal within a frequency range in response to changes in a control voltage. The frequency range of the periodic output signal varies when the first control signal causes the regulated supply voltage to change from the first voltage to the second voltage.