Integrated Switch-Mode and Linear Regulator for RF Noise Reduction
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Solution Overview
Problem
RF circuitry in mobile wireless communication devices experiences noise and inefficiency due to the use of linear voltage regulators, which shortens battery life, while switch-mode power supplies are noisy and not desirable for RF sections.
Innovation Solution
A two-stage power supply integrating a switching voltage regulator and a linear voltage regulator within a common integrated circuit housing, without a voltage control loop, where the switching regulator maintains a voltage level sufficient for the linear regulator to maintain a constant output voltage, using semiconductor switching and current pass stages with feedback loops to optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a linear voltage regulator is used to power RF circuitry, then noise is minimized, but efficiency deteriorates and battery life is shortened
Solution Approach 1:
The power supply is divided into two separate stages: a switch-mode power supply stage for efficient power conversion and a linear regulator stage for noise filtering. Each stage performs its specialized function independently, with the SMPS handling efficiency and the linear regulator handling noise reduction, thereby resolving the contradiction between efficiency and noise performance.
2Loss of energy
If a switch-mode power supply is used to improve efficiency, then battery life is extended, but noise increases and RF circuitry performance deteriorates
Solution Approach 1:
The power supply function is segmented into two distinct stages: the switch-mode power supply stage that handles efficient power conversion, and the linear regulator stage that handles noise filtering. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The linear regulator acts as an intermediary between the switch-mode power supply and the RF circuitry. It filters out the noise generated by the SMPS before the power reaches the sensitive RF components, thereby allowing the SMPS to operate at high efficiency while protecting the RF circuitry from noise.
3Power
If the voltage applied to the linear regulator is increased to maintain efficiency, then power delivery is improved, but the voltage drop across the regulator increases and efficiency diminishes
Solution Approach 1:
The power supply is segmented into two stages with distinct voltage handling roles. The switch-mode power supply stage handles the high voltage input and performs efficient power conversion, while the linear regulator stage operates at a lower, stabilized voltage level appropriate for RF circuitry. This segmentation allows the system to deliver adequate power while maintaining efficiency.
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
This configuration maintains output voltage above the dropout voltage of the linear regulator without complex control circuitry, enhancing efficiency and reducing noise, thus extending battery life and minimizing communication errors.
Implementation Method 1
a semiconductor switching stage coupled to the first input and configured to provide a first DC voltage signal from the received DC input signal
Implementation Method 2
a semiconductor current pass stage coupled to the output of the switching voltage regulator and configured to provide a constant second DC output voltage signal from the first DC voltage signal
Data Source
AI summary
A power supply includes a switching voltage regulator, and a linear voltage regulator coupled electrically in series with the switching voltage regulator. The switching voltage regulator includes a first input for receiving a DC input signal, a semiconductor switching stage coupled to the first input and configured to provide a first DC voltage signal from the received DC input signal. The magnitude of the first DC voltage signal is less than the received DC input signal. The linear voltage regulator includes a semiconductor current pass stage coupled to the output of the semiconductor switching stage and configured to provide a constant second DC output voltage signal from the first DC voltage signal. The voltage regulators are implemented together within a common integrated circuit housing.