Differential Receiver Circuit for Single-Antenna TX Signal Cancellation
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Solution Overview
Problem
The requirement for a high gain amplifier in UWB pulsed radar receivers to detect close targets leads to design limitations, including the need for high-powered transmitters that can damage receiver circuitry, restricting the radar architecture to either two-port full-duplex or single-port half-duplex designs, which compromise near-zero range detection and device form factor.
Innovation Solution
A differential transceiver circuit that enables pseudo-full-duplex operation using a single antenna, featuring a differential pair of signal paths, a differential amplifier, a differential transmitter, a switching network, and an injection circuit to cancel out transmit signals, allowing continuous receive operation during transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high gain amplifier is used in the receiver to detect close targets, then the receiver sensitivity is improved, but the transmitter power must be increased which can damage the receiver circuitry
Solution Approach 1:
The patent applies this principle by using the strong transmit signal, which would normally damage the receiver, as a reference signal for cancellation. The transmit signal is injected into the receive path and subtracted from the received signal, converting the harmful high-power transmit signal into a useful reference for eliminating interference and enabling continuous reception during transmission.
2Measurement precision
If a two-port full-duplex design is used with separate transmit and receive antennas, then the receiver can continuously detect close targets, but the device area increases significantly
Solution Approach 1:
The patent merges the transmit and receive functions into a single antenna port, combining what would traditionally require separate antennas. By using signal cancellation techniques, the system achieves full-duplex operation (continuous reception during transmission) with a single antenna, significantly reducing the device area while maintaining near-zero range detection capability.
3Area of stationary object
If a single-port half-duplex design is used to reduce device area, then the form factor is improved, but the receiver cannot receive signals during transmission
Solution Approach 1:
The patent enables continuous reception during transmission by injecting the transmit signal into the receive path and canceling it out. This allows the receiver to continuously process signals without interruption during transmit phases, maintaining productivity and enabling detection of targets at near-zero range that would otherwise be missed during transmission intervals.
Data Source
AI summary
A differential transceiver circuit coupled to a single antenna interface, the transceiver circuit comprising: a differential pair of signal paths, comprising a first signal path and a second signal path; differential amplifier, having an input arranged to receive a receive signal from the antenna interface; a differential transmitter arranged to generate a differential pair comprising a first transmit signal connected to the first signal path and a second transmit signal connected to the second signal path; a switching network arranged to divert the amplifier output on the second signal path to a signal ground node. The receive signal on one signal path is diverted to ground. The transmit signal corresponding to the other differential signal path is inserted so that the same transmit signal is present on both differential signal paths. When processed by differential downstream components with high common-mode rejection, the transmit signals cancel out.