Integrated RF Front-End Balun Topology Without T/R Switch Loss
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Solution Overview
Problem
Conventional radio frequency (RF) front-ends for short-range wireless systems face challenges in achieving compact design, reduced energy dissipation, minimized signal loss, and lower manufacturing costs while maintaining high linearity and performance, particularly in noisy environments and system-on-a-chip (SOC) scenarios.
Innovation Solution
The integration of a center-tapped inductor balun with a selector circuit that switchlessly couples to either a receiver RF amplifier or a power amplifier, using active components like transistors, to convert between single-ended and differential signals, eliminating the need for a transmit/receive switch and optimizing impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmit and receive (T/R) switch is used to couple the antenna to either the LNA or PA, then the system can achieve transmission and reception functionality, but the switching losses directly affect the receiver sensitivity and transmitter output power delivery
Solution Approach 1:
The patent extracts and removes the T/R switch from the signal path by using a balun with a center-tapped inductor that can be switchlessly coupled to different circuit configurations. The center-tap is connected to a switching node that can be controlled to connect to either the LNA or PA without inserting a traditional switch in the RF signal path, thereby eliminating switching losses while maintaining transmission and reception functionality.
2Area of stationary object
If the entire RF front-end is integrated on-chip, then the chip area is reduced and manufacturing cost is lowered, but the design complexity increases and performance optimization becomes more difficult
Solution Approach 1:
The patent implements a multi-functional balun circuit that serves multiple purposes: it performs single-ended to differential signal conversion, provides impedance transformation, and enables switchless coupling between the antenna and either the LNA or PA through its center-tapped configuration. This universal component replaces what would traditionally require multiple separate components, thereby reducing chip area while managing integration complexity through functional consolidation.
3Adaptability or versatility
If a T/R switch is used to toggle the antenna between Tx and Rx, then transmission and reception can be implemented, but the device complexity increases due to additional components and control circuitry
Solution Approach 1:
The patent merges the functions of the T/R switch, balun, and impedance matching network into a single integrated circuit configuration. The center-tapped inductor of the balun is connected to a switching node that can be controlled to connect to either the LNA or PA, combining multiple functions into one structure and eliminating the need for separate T/R switch components and associated control circuitry.
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 results in a compact RF front-end with reduced signal loss, energy dissipation, and manufacturing costs, while maintaining high performance and linearity, by selectively activating active components and eliminating switching losses.
Implementation Method 1
the balun receives a single-ended signal through the first node of the center-tapped inductor and converts the single-ended signal to a differential signal
Data Source
AI summary
An integrated RF front-end circuit comprising a balun, a receiver amplifier, a power amplifier, and a selector circuit is provided. The balun comprises a center-tapped inductor having a first node, a center-tap switchlessly coupled to a fixed voltage, and a second node. The balun receives a single-ended signal through the first node to produce a differential signal at the first and second nodes. The differential signal is provided to balanced input lines of the receiver amplifier. Balanced output lines of the power amplifier provide a differential signal to the first and second nodes. The balun converts the differential signal to a single-ended signal. The single-ended signal is available at the first node of the center-tapped inductor. The selector circuit activates the receiver amplifier and deactivates the power amplifier, and vice versa. The power amplifier may comprise only a single-ended output line connected to either the first or the second node.