Supply-Regulated VCO with Active Loop Filter for Low-Noise PLLs
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Solution Overview
Problem
Existing voltage controlled oscillators (VCOs) in phase locked loops are vulnerable to external supply noise, leading to increased power consumption and limited operation range due to the need for high performance operational amplifiers and passive loop filters, which also generate noise and restrict the operation of charge pumps.
Innovation Solution
A supply regulated voltage controlled oscillator (SRVCO) with an operational amplifier as a supply regulator and a negative feedback circuit, incorporating an active loop filter using passive elements, which separates the output voltage of the charge pump from the control voltage of the oscillator, allowing for efficient noise reduction and extended operation range without additional power or chip area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high performance operational amplifiers and passive loop filters are used to reduce external supply noise, then noise reduction is improved, but power consumption increases and operation range is limited
Solution Approach 1:
The patent segments the traditional loop filter function into two parts: a passive loop filter for basic filtering and a separate supply regulator circuit with operational amplifier for active noise suppression. This segmentation allows each component to be optimized independently, reducing the need for high-performance (and high-power) operational amplifiers while maintaining noise reduction effectiveness.
Solution Approach 2:
The patent introduces a supply regulator circuit as an intermediary between the external power supply and the VCO. This intermediary actively compensates for supply noise before it reaches the oscillator, protecting the VCO from noise while allowing the use of simpler, lower-power operational amplifiers compared to using high-performance amps directly in the loop filter.
2Object-affected harmful factors
If high performance operational amplifiers and passive loop filters are used to reduce external supply noise, then noise reduction is improved, but device complexity increases
Solution Approach 1:
The patent merges the supply regulator function with the loop filter function into a single integrated circuit block. The operational amplifier serves dual purposes: regulating the supply voltage to the VCO and working with the passive loop filter components to provide active noise suppression. This merging reduces the number of separate components and simplifies the overall circuit architecture.
Solution Approach 2:
The operational amplifier in the patent performs multiple functions simultaneously: it acts as a supply regulator to clean the power supply, works as an active element in the loop filter for noise filtering, and helps maintain loop stability. This multi-functionality reduces the need for separate dedicated components, thereby reducing device complexity.
3Device complexity
If passive loop filters are used, then device complexity is reduced, but noise performance deteriorates and charge pump operation is restricted
Solution Approach 1:
The supply regulator circuit acts as an intermediary that actively suppresses noise before it reaches the charge pump and VCO. This active noise suppression mechanism works in conjunction with the passive loop filter, allowing the use of simple passive components while achieving superior noise performance through the regulatory action of the operational amplifier circuit.
Solution Approach 2:
The patent changes the operational parameters of the circuit by using the supply regulator to maintain stable voltage levels and reduce noise across different operating conditions. This allows the charge pump to operate effectively over a wider range of frequencies and conditions while maintaining good phase noise performance, without requiring complex active loop filter components.
4Use of energy by moving object
If supply voltage is reduced to lower power consumption, then power consumption is reduced, but minimum external supply voltage requirement increases due to noise sensitivity
Solution Approach 1:
The patent converts the potential harm of supply noise into a benefit by using the supply regulator circuit to detect and actively compensate for noise disturbances. The operational amplifier monitors supply variations and adjusts the regulation accordingly, allowing the system to operate at lower voltages with reduced power consumption while maintaining noise immunity through this active compensation mechanism.
Solution Approach 2:
The supply regulator circuit dynamically adjusts its regulation parameters to maintain optimal performance across different supply voltage levels. This allows the VCO to operate effectively at lower supply voltages for reduced power consumption, while the regulator ensures that noise sensitivity is compensated for, effectively lowering the minimum supply voltage requirement compared to traditional designs.
Data Source
AI summary
The inventive concept relates to a supply regulated voltage controlled oscillator having a function of an active loop filter by sharing one operational amplifier without additional use of active elements in a supply regulated voltage controlled oscillator using an operational amplifier as a supply regulator, and a phase locked loop using the same.