SOI RF Switch Level Shifters for High Linearity and Low Ron
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Solution Overview
Problem
Current RF switching technologies face challenges in providing targeted linearity and reducing complexity and cost in MIMO systems, particularly due to the increased number of RF hardware components required, which can be mitigated by implementing high-linearity switches with voltage level shifters that provide high positive and negative voltages efficiently.
Innovation Solution
The implementation of a voltage level circuit with multiple transistor stacks and cross-coupled PMOS transistors, along with charge pumps, to generate and manage high voltages (e.g., ±2.5 V, ±3.3 V, ±4 V) for RF switches, reducing the stress on transistors and improving switch performance by integrating level shifters and control circuits on SOI switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple RF hardware components are used to increase data throughput in MIMO systems, then data throughput is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple RF switch control functions into a single integrated RF switch device with built-in voltage level shifters. The control circuitry and voltage generation circuits are merged with the switch fabric, allowing multiple RF paths to be controlled through a unified structure rather than requiring separate hardware components for each switch.
Solution Approach 2:
The RF switch device is designed with multi-functionality to handle both switching and voltage level shifting operations. The voltage level shifter circuits are integrated directly into the switch structure, enabling the same device to perform both signal routing and voltage translation functions that would traditionally require separate components.
2Reliability
If high voltages are applied to improve switch linearity and reduce on-resistance, then switch performance is improved, but transistor stress and reliability concerns increase
Solution Approach 1:
The voltage level shifting function is segmented into dedicated circuits that are integrated with the RF switch. Instead of applying high voltages directly to control the switch, separate voltage level shifter circuits generate the appropriate high voltage levels (e.g., ±2.5V, ±3.3V, ±4V) and apply them through controlled pathways, distributing the stress management across multiple specialized components.
Solution Approach 2:
Voltage level shifter circuits serve as intermediary components between the low-voltage control logic and the high-voltage switch terminals. These intermediate circuits translate control signals to the appropriate high voltage levels while providing isolation and protection, preventing direct exposure of transistors to excessive voltage stress.
3Reliability
If voltage level shifters are integrated into RF switches, then switch performance and linearity are improved, but circuit complexity increases
Solution Approach 1:
The voltage level shifter circuits are merged with the RF switch structure in an integrated manner. The control circuitry, voltage generation circuits, and switch fabric are combined into a single unified device, eliminating the need for separate external voltage level shifting components and reducing overall system complexity despite the added functionality.
Data Source
AI summary
Disclosed herein are silicon-on-insulator (SOI) switches and associated control circuits having level shifters configured to provide increased voltages (positive and/or negative) to the switches. The disclosed level shifters can be configured to provide increased voltages and can be used with high-linearity switches and/or can improve the linearity of switches. The improved switch performance can improve front end module performance for applications such as carrier aggregation (CA) and multiple input multiple output (MIMO) as well as with protocols such as Long-Term Evolution Advanced (or LTE-A).