Integrated Rx/Tx Switch Using Cascode Isolation on Silicon

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Solution Overview

Problem

Existing radio transmitter and receiver circuits on a single substrate face challenges due to large voltage swings, necessitating external Rx/Tx switches on PCBs, which require separate pins for transmitter and receiver connections, compromising performance.

Innovation Solution

Integration of a cascode amplifier and low-noise amplifier on a silicon substrate, with a radio frequency input/output channel, and a receive and transmit modem, forming a unified Rx/Tx circuit that switches between transmit and receive modes using a controller to manage voltage and impedance, allowing all components to be integrated on a single chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the Rx/Tx switch is formed as an external component on a PCB, then satisfactory performance can be achieved, but separate pins are needed for transmitter and receiver connections, increasing device complexity

Engineering Contradiction:

ImproveperformanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the Rx/Tx switch directly into the silicon substrate alongside the power amplifier and low noise amplifier, eliminating the need for external PCB-based switches and reducing the number of required pins while maintaining satisfactory performance through careful layout and impedance matching

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If the Rx/Tx switch is integrated on silicon using CMOS technology, then device complexity is reduced, but performance becomes quite poor

Engineering Contradiction:

Improvedevice complexityVSAvoidperformance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent employs different transistor types (NMOS and PMOS) in specific locations within the cascode configuration to optimize local electrical characteristics, allowing the integrated switch to achieve both low complexity and satisfactory performance by tailoring the electrical properties at critical points

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the power amplifier and low noise amplifier are connected together, then integration is achieved, but the LNA input must be protected from large voltage swings, requiring additional protection mechanisms

Engineering Contradiction:

ImproveintegrationVSAvoidvoltage swing

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The cascode amplifier serves as an intermediary device between the power amplifier and low noise amplifier, providing galvanic isolation and protecting the LNA input from large voltage swings while enabling integration on a single silicon substrate

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250211281A1Integrated receiver transmitter switch

Publication Date: 2025.06.26 TEXAS INSTRUMENTS INC

AI summary

A communication integrated circuit (IC) device comprises a silicon substrate and a radio circuit formed on the silicon substrate. The radio circuit comprises a receive and transmit circuit that comprises a cascode amplifier and a low-noise amplifier coupled with the cascode amplifier. The radio circuit also comprises a radio frequency input/output channel configured to be coupled with a radio antenna. The communication IC device further comprises a receive modem coupled with the low-noise amplifier and a transmit modem coupled with the cascode amplifier.