Switched-Capacitor Drive Supply for NMOS RF Supply Modulators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio-frequency (RF) power amplifier systems face inefficiencies due to the limited availability of supply voltage levels required to drive NMOS transistors, leading to larger and less efficient circuit designs.
Innovation Solution
A differential switched-capacitor converter circuit is used to generate output voltages greater than the input voltages, enabling the use of NMOS transistors by providing sufficient gate drive supply voltages in RF supply modulation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If supply voltage levels are limited to available input voltages, then circuit simplicity is maintained, but system size increases and efficiency decreases due to inability to use NMOS transistors
Solution Approach 1:
The patent implements dynamic voltage generation by switching between different capacitor configurations (series and parallel) to produce variable output voltages. The switched-capacitor converter dynamically adjusts the output voltage level based on operational requirements, enabling the system to provide higher voltages than the fixed input voltages while maintaining circuit simplicity through reusable capacitors and switches.
Solution Approach 2:
The patent introduces switched-capacitor converter circuitry as an intermediary between the available input voltage rails and the power amplifier stage. This intermediary generates the required higher gate drive voltages for NMOS transistors by capacitively storing and combining voltage differences, thereby enabling NMOS device operation without directly requiring higher input voltage rails.
2Loss of energy
If higher supply voltage levels are generated, then NMOS transistor efficiency improves, but circuit complexity increases
Solution Approach 1:
The switched-capacitor converter circuit performs multiple functions: it generates higher output voltages for NMOS gate drives, provides isolated voltage generation from input rails, and enables efficient power conversion. The same capacitors and switches are reused across different voltage generation paths, reducing overall component count and complexity while achieving multiple objectives simultaneously.
Solution Approach 2:
The patent changes the voltage parameter dynamically by switching capacitor configurations. By altering the connection topology (series vs. parallel) of the switched capacitors, the circuit generates different output voltage levels from the same input voltages, thereby adapting to different operational requirements without requiring separate voltage generation circuits for each level.
3Loss of energy
If NMOS transistors are used, then power efficiency improves, but availability of sufficient gate drive voltage decreases
Solution Approach 1:
The switched-capacitor converter dynamically generates the required gate drive voltages for NMOS transistors by switching between different capacitor configurations. This dynamic voltage generation ensures that sufficient voltage levels are always available to properly drive NMOS devices, enabling their use in the power amplifier stage while maintaining the ability to adapt to different voltage requirements.
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 solution allows for smaller and more efficient RF supply modulation systems by enabling the use of NMOS transistors, which improves overall system size and efficiency.
Implementation Method 1
a first capacitor configured to charge to a voltage equal a difference between the first voltage and the output voltage
Implementation Method 2
a second capacitor configured to charge to a voltage equal to a difference between the first voltage and the second voltage
Implementation Method 3
a plurality of conductive paths coupled to the first capacitor and the second capacitor and having two states
Data Source
AI summary
A circuit configured to receive a first and second voltages and generate an output voltage, the circuit comprising: a first capacitor configured to charge to a voltage equal a difference between the first voltage and the output voltage; a second capacitor configured to charge to a voltage equal to a difference between the first voltage and the second voltage; and a plurality of conductive paths coupled to the first and second capacitors. In a first state, the conductive paths are configured to cause the second capacitor to charge to the voltage equal to the difference between the first voltage and the second voltage. In a second state, the conductive paths are configured to cause the second capacitor to be connected in parallel with the first capacitor to cause the first capacitor to charge to the voltage equal to the difference between the first voltage and the output voltage.