Constant Input Current Filter for Wireless Radios
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Solution Overview
Problem
Conventional power conversion circuits fail to meet the CE101 requirement for constant input current in wireless radios using modern RF waveforms, leading to excessive size and weight due to large inductors needed for LC filters.
Innovation Solution
A constant input current filter system utilizing an n-type field effect transistor as a current source, coupled with capacitors and resistors, to draw a constant input current and provide output current to a load, ensuring minimal ripple current from the power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an LC filter is installed to limit ripple current, then the CE101 requirement is met, but the filter becomes extremely large and heavy at low frequencies
Solution Approach 1:
The patent changes the operating parameters of the power conversion circuit by implementing constant input current mode operation. The control circuit monitors and regulates the input current to maintain it constant, thereby reducing ripple current without requiring large inductors. This parameter change allows meeting CE101 requirements with a much smaller, lighter filter design.
Solution Approach 2:
The patent replaces the mechanical/passive LC filter approach with an active control system. Instead of relying on large inductors and capacitors to passively filter ripple current, the system uses an active control circuit to dynamically regulate the input current, substituting electronic control for passive mechanical filtering components.
2Reliability
If an LC filter is installed to limit ripple current, then the CE101 requirement is met, but the filter size becomes extremely large at low frequencies
Solution Approach 1:
The patent changes the operating parameters of the power conversion circuit by implementing constant input current mode operation. The control circuit monitors and regulates the input current to maintain it constant, thereby reducing ripple current without requiring large inductors. This parameter change allows meeting CE101 requirements with a much smaller, lighter filter design.
Solution Approach 2:
The patent replaces the mechanical/passive LC filter approach with an active control system. Instead of relying on large inductors and capacitors to passively filter ripple current, the system uses an active control circuit to dynamically regulate the input current, substituting electronic control for passive mechanical filtering components.
3Device complexity
If conventional power conversion circuits are used, then the circuit design is simple, but the input current has the same form as RF power output causing CE101 failure
Solution Approach 1:
The patent replaces the mechanical/passive LC filter approach with an active control system. Instead of relying on large inductors and capacitors to passively filter ripple current, the system uses an active control circuit to dynamically regulate the input current, substituting electronic control for passive mechanical filtering components.
Solution Approach 2:
The patent implements a feedback control mechanism where the control circuit continuously monitors the input current and adjusts the power conversion circuit operation to maintain constant current. This feedback loop ensures CE101 compliance by actively regulating ripple current based on real-time conditions.
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 system effectively reduces ripple current, enabling wireless radios to comply with CE101 requirements and reducing the size and weight of the radio by using a capacitor to supply additional current during peak demand, thus maintaining a constant input current.
Implementation Method 1
a current source configured to draw a constant input current from a power source and to generate an output current, the current source comprising an n-type field effect transistor that is biased to operate as a constant current source
Implementation Method 2
the current source is configured to provide the output current to a first capacitor and charge the first capacitor during a first time period associated with operation of a load; wherein the current source is configured to provide the output current to the load and the first capacitor is configured to provide an additional current to the load during a second time period associated with operation of the load
Data Source
Figure 1~3
Figure 4~5B
Figure 6
AI summary
A system includes a capacitor (118) and a current source (116) configured to draw a constant input current from a power source (110) and to generate an output current. The current source includes an n-type field effect transistor (202) that is biased to operate as a constant current source. The current source is configured to provide the output current to the capacitor and charge the capacitor during a first time period associated with operation of a load. The current source is also configured to provide the output current to the load and the capacitor is configured to provide an additional current to the load during a second time period associated with operation of the load. The load could represent an electronic device having a time-varying output power characteristic, such as a wireless radio.