VCO Regulator Current Mirror for Low-Noise PVT-Stable Bias
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Solution Overview
Problem
Existing voltage regulators for voltage-controlled oscillators (VCOs) in wireless communication networks are not power efficient, introduce noise, and are sensitive to process technology, power supply voltage, and temperature variations, which affects phase noise performance and efficiency.
Innovation Solution
A power-efficient, low-noise voltage regulating circuit using a current mirror with a source follower topology, where the reference current is reused as part of the VCO current, and a current sensing circuit with a current mode comparator provides feedback to adjust the VCO current, making it insensitive to process, voltage, and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional voltage regulator is used for VCO, then the regulated voltage can be provided, but power efficiency is poor and noise is introduced
Solution Approach 1:
The reference current is reused to provide both the regulation function and part of the VCO bias current. The current mirror configuration allows the same reference current to serve dual purposes: establishing the regulated voltage level and providing bias current for the VCO, thereby eliminating waste and improving power efficiency without introducing additional noise sources
Solution Approach 2:
The regulation function and VCO bias current provision are merged into a single current mirror structure. The bias branch and main branch of the current mirror work together to simultaneously achieve voltage regulation and provide the necessary bias current, reducing the number of separate components and minimizing noise while improving power efficiency
2Reliability
If a conventional voltage regulator is used for VCO, then the regulated voltage can be provided, but the circuit is sensitive to process, voltage, and temperature variations
Solution Approach 1:
A feedback mechanism is implemented where the regulated voltage is monitored and used to adjust the reference current through the current mirror. This feedback loop compensates for PVT variations by dynamically adjusting the current levels to maintain stable regulation, thereby improving reliability and reducing phase noise sensitivity to environmental changes
Solution Approach 2:
The circuit utilizes parameter changes in the transistor operating points to compensate for PVT variations. By designing the current mirror and source follower with specific biasing conditions, the circuit maintains stable performance across process, voltage, and temperature changes, improving reliability without degrading phase noise performance
3Use of energy by moving object
If the reference current is reused as VCO current, then power efficiency is improved, but the circuit complexity increases
Solution Approach 1:
The current mirror structure is designed to perform multiple functions simultaneously: voltage regulation, reference current generation, and VCO bias current provision. This multi-functionality approach improves power efficiency by eliminating redundant components while the modular current mirror design keeps the circuit complexity manageable through systematic component arrangement
Data Source
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AI summary
Certain aspects of the present disclosure provide voltage regulating circuits which are power efficient, low noise, and substantially insensitive to changes in process technology, power supply voltage, and temperature. Such circuits may be used to provide the regulated voltage for a voltage-controlled oscillator (VCO), for example, as found in a radio frequency front end (RFFE). One example voltage regulating circuit generally includes a current source configured to supply or sink a reference current and a current mirror having a bias branch and a main branch, wherein the bias branch is connected with the current source, wherein the main branch includes a source follower to provide the regulated voltage, and wherein the reference current is available at a node for the regulated voltage.