Integrated TRX Switch Topology for High Isolation and Low Loss
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Solution Overview
Problem
Conventional high isolation transmit-receive (TRX) switches increase chip area and loss in both transmit and receive chains, and require active technologies that limit the linearity of the transmit chain due to the need for high voltage tolerance.
Innovation Solution
An integrated TRX switch is implemented using a series capacitor and a shunt switch, combining output and input impedance matching networks, suitable for differential and single-ended applications, eliminating the need for high breakdown devices and suitable for low voltage submicron transistor technologies, which reduces chip area and provides high isolation between transmit and receive circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional high isolation TRX switches are used, then isolation between transmit and receive chains is improved, but chip area increases and signal loss increases
Solution Approach 1:
The patent combines the output matching network of the transmit chain and the input matching network of the receive chain into a single integrated TRX switch structure. This merging eliminates the need for separate matching networks, thereby reducing chip area while maintaining high isolation through the integrated design that uses a single pole switch with capacitive elements.
Solution Approach 2:
The integrated TRX switch structure serves multiple functions simultaneously: it provides impedance matching for both transmit and receive chains, acts as the isolation switch, and provides signal routing. This multi-functionality reduces the overall component count and chip area while maintaining the required isolation performance.
2Object-affected harmful factors
If conventional high isolation TRX switches are used, then isolation between transmit and receive chains is improved, but signal loss and noise factor increase
Solution Approach 1:
The patent changes the electrical parameters of the switch by using capacitive elements (series and shunt capacitors) instead of traditional resistive or inductive matching networks. This parameter change enables the switch to achieve high isolation while minimizing signal loss and noise factor, as the capacitive elements have lower loss characteristics at the operating frequency.
3Object-affected harmful factors
If active technologies that withstand high voltages are used, then isolation is improved, but linearity of the transmit chain is limited
Solution Approach 1:
The patent uses low breakdown voltage transistors (which would traditionally be considered less robust for high voltage applications) in the integrated TRX switch structure. The capacitive design allows these lower-voltage-rated devices to function effectively, improving linearity while still achieving the required isolation performance through the circuit topology rather than relying on high-voltage device characteristics.
Data Source
AI summary
An apparatus includes a transceiver circuit, a series capacitor, and a shunt switch. The transceiver circuit may comprise a transmit chain including an output matching network and a receive chain including an input matching network. An output of the output matching network may be connected directly to an input/output of the transceiver circuit. The series capacitor may be connected between an input of the input matching network and the output of the output matching network. The shunt switch may be connected between the input of the input matching network and a circuit ground potential of the transceiver circuit.