High voltage digital power amplifier
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Solution Overview
Problem
Conventional digital power amplifiers face limitations in output power due to their reliance on low supply voltages, which restricts their ability to support higher transmit powers required for longer distance communications, especially in cellular applications, and are inefficient due to increased current demands and reliance on multiple DC-DC converters.
Innovation Solution
The proposed architecture increases the supply voltage of switched capacitor digital power amplifiers through transistor stacking, allowing equal voltage stress distribution and using a capacitive divider to reduce oxide stress, eliminating the need for additional DC-DC converters and enhancing efficiency by reducing current requirements and IR drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional switched capacitor digital power amplifier topology is used, then power efficiency is improved, but output power is limited due to low supply voltage
Solution Approach 1:
The power amplifier output stage is segmented into multiple transistor stacks connected in series. Each stack handles a portion of the total voltage, enabling the system to achieve high output power while maintaining the efficiency benefits of digital switching operation. The segmentation allows voltage to be distributed across multiple devices rather than requiring a single high-voltage transistor.
Solution Approach 2:
The patent transitions from a single-transistor architecture to a multi-dimensional transistor stacking arrangement. By organizing transistors in series stacks and using capacitive dividers to distribute voltage stress, the system adds a vertical dimension to the voltage handling capability, enabling high power output without compromising the low-voltage digital switching efficiency.
2Power
If supply voltage is increased to support higher output power, then output power is improved, but current demand increases causing higher IR drops and reduced efficiency
Solution Approach 1:
The current path is segmented through multiple transistor stacks in series. By distributing the voltage across multiple stacks rather than using a single high-voltage transistor, the system achieves high output power with lower current demand, reducing IR drops and maintaining efficiency in the power supply network.
Solution Approach 2:
The patent changes the voltage parameter distribution across the power amplifier stages. By using capacitive dividers to create specific voltage ratios (such as 1:2 or 1:3 divisions), the system optimizes the voltage and current parameters to achieve high power output while minimizing power loss in the supply network.
3Power
If multiple DC-DC converters are added to support higher voltage operation, then output power capability is improved, but device complexity and cost increase
Solution Approach 1:
The transistor stacks and capacitive dividers serve multiple functions simultaneously: they enable high voltage operation, distribute voltage stress to protect individual devices, and eliminate the need for separate DC-DC converters. This multi-functionality reduces overall device complexity while achieving the desired power capability.
Solution Approach 2:
The power amplifier circuit generates its own high voltage operation internally through the transistor stacking and capacitive division mechanism, without requiring external DC-DC conversion stages. The circuit serves itself by creating the necessary voltage conditions through its own components, eliminating the need for additional complexity.
4Power
If transistor stacking is used to increase supply voltage, then output power is improved, but voltage stress on individual transistors increases beyond safe limits
Solution Approach 1:
The total voltage stress is segmented and distributed across multiple transistor stacks connected in series. Each transistor or stack handles only a portion of the total voltage, keeping individual voltage stress within safe operating limits while enabling the overall system to achieve high output power capability.
Solution Approach 2:
Capacitive dividers are introduced as intermediary elements between the transistor stacks. These capacitors actively manage voltage distribution and stress, ensuring that no single transistor exceeds its maximum voltage rating while maintaining the high supply voltage needed for high power operation.
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 approach enables higher output power transmission with improved efficiency, reduced cost, and increased reliability by maintaining voltage stress within safe limits, while also minimizing sensitivity to load changes and enhancing power efficiency.
Implementation Method 1
a capacitive divider to reduce oxide stress
Data Source
AI summary
Techniques are disclosed to allow for a switched capacitor digital power amplifier (PA) that operates using high supply voltage levels beyond twice the maximum voltage rating for any of the transistor terminals such as Vds/Vdg/Vsg.