Transmit-Receive Switch Architecture for Pre-Transmit Isolation
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Solution Overview
Problem
In multi-mode communication devices, frequency overlap between transmit and receive bands leads to power leakage during pre-transmit times, violating GSM transmit spectrum masks and requiring additional switches that increase complexity and cost.
Innovation Solution
A transmit-receive switch architecture with a first switch coupled to transmit circuitry and a second switch coupled to receive circuitry, which is configured to ground the receive circuitry during pre-transmit times when the transmit circuitry's power source is enabled, using control signals to manage the switches and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transmit-receive switch is used to control both transmit and receive paths, then device complexity is reduced, but RF power leakage occurs during pre-transmit times due to frequency overlap between transmit and receive bands
Solution Approach 1:
The patent divides the single switch control function into two separate switches: a first switch controlling the transmit path and a second switch controlling the receive path. This segmentation allows independent control of each path, enabling the second switch to ground the receive circuitry during pre-transmit times while the first switch manages transmit signals, thereby preventing RF power leakage without requiring complex additional components.
Solution Approach 2:
The patent introduces a grounding mechanism as an intermediary element connected to the receive circuitry through the second switch. This intermediary provides a safe discharge path for RF power during pre-transmit times, acting as a mediator that prevents harmful leakage while maintaining normal receive operations. The grounding path effectively neutralizes the harmful RF energy without interfering with the primary transmit-receive switching function.
2Object-generated harmful factors
If additional switches are added to prevent RF power leakage during pre-transmit times, then harmful emissions are reduced, but device complexity and cost increase
Solution Approach 1:
The patent designs the second switch to perform multiple functions: it controls the receive path during normal operations and simultaneously provides pre-transmit isolation by grounding the receive circuitry when needed. This multi-functionality eliminates the need for separate dedicated isolation switches, reducing overall device complexity while effectively preventing RF power emissions during pre-transmit times.
3Reliability
If the receive circuitry is isolated during pre-transmit times, then compliance with GSM transmit spectrum masks is achieved, but signal reception capability is temporarily reduced
Solution Approach 1:
The patent implements periodic switching of the second switch based on transmission timing requirements. During pre-transmit times, the switch grounds the receive circuitry to ensure spectrum mask compliance. During normal receive periods, the switch transitions to connect the receive circuitry to the antenna for signal reception. This periodic action ensures both regulatory compliance and operational effectiveness without permanent degradation of receive capability.
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 effectively reduces or eliminates RF power emission through the receive circuitry during pre-transmit times, maintaining compliance with GSM transmit spectrum masks without the need for additional switches, thus simplifying the device and reducing costs.
Implementation Method 1
a second switch coupled to receive circuitry and to ground, wherein the second switch is configured to couple the receive circuitry to ground during a time period in which a power source associated with the transmit circuitry is enabled
Data Source
AI summary
A transmit-receive switch architecture comprises a first switch coupled to transmit circuitry and to an antenna, a second switch coupled to receive circuitry and to ground, wherein the second switch is configured to couple the receive circuitry to ground during a time period in which a power source associated with the transmit circuitry is enabled.