RF Front End Integrated Transmit Receive Switch
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Solution Overview
Problem
Conventional transceivers do not effectively isolate transmitters from receivers, leading to increased cost and size due to off-chip integration of RF front end components, which complicates independent optimization and results in performance degradation.
Innovation Solution
An RF front end system with on-chip integration of a power amplifier, low noise amplifier, and transmit/receive switch, sharing a common matching network and optimal impedance, with the switch integrated between the power amplifier and low noise amplifier to minimize loading and switch loss, and utilizing common-gate or cross-coupled LNA designs to match impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF front end components are integrated off-chip to isolate transmitters from receivers, then isolation between transmitters and receivers is improved, but cost and size of the RF front end system increase
Solution Approach 1:
The patent merges the T/R switch with the PA output stage by using the PA's output transistor as the switch element. This integration eliminates the need for a separate off-chip T/R switch component, reducing system size and cost while maintaining transmitter-receiver isolation through the shared transistor structure
Solution Approach 2:
The PA output transistor serves multiple functions simultaneously: it acts as both the power amplifier output stage and the T/R switch. This multi-functionality reduces the total component count and integration complexity while achieving both amplification and isolation functions
2Loss of energy
If T/R switch is integrated between PA and LNA, then switch loss is minimized and independent optimization is enabled, but device complexity increases
Solution Approach 1:
The T/R switch is merged with the PA output stage, sharing the same transistor and matching network components. This integration minimizes switch loss by eliminating additional switching elements and reduces the number of external connections required
Solution Approach 2:
The patent segments the RF front end into distinct functional blocks (PA with integrated T/R switch, LNA with integrated T/R switch, shared matching network) that can be independently optimized while maintaining low switch loss through minimal interconnection elements
3Device complexity
If common matching network is shared between PA and LNA, then package pin count is reduced, but impedance matching difficulty increases
Solution Approach 1:
A single matching network is designed to serve dual functions: matching the PA output to the antenna during transmission and matching the LNA input to the antenna during reception. This universal matching network reduces package pin count by eliminating redundant matching components while achieving both matching objectives through proper circuit design
Data Source
AI summary
A Radio Frequency (RF) front end system and method are disclosed. The RF front end system comprises an antenna, a matching network coupled to the antenna, a power amplifier (PA) coupled to the matching network via a port on a transmit path, a low noise amplifier (LNA) coupled to the matching network via the port on a receive path and at least one transmit/receive switch (T/R SW) coupled between the port and at least one of the PA and LNA.