Transceiver Leakage Compensation Circuit for TX-RX Isolation
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Solution Overview
Problem
In transceiver systems, transmitter (TX) leakage signals often interfere with receiver (RX) inputs due to limited isolation, leading to challenges in linearity and sensitivity, particularly in frequency division duplex (FDD) or full duplex (FDX) modes, where TX leakage can saturate ADC and LNA components.
Innovation Solution
A leakage compensation circuit and system that includes a digital-to-analog converter (DAC) and an adjustment circuit to generate a compensation signal aligned with the TX leakage signal, which is used to adjust the input signal of the RX, preventing saturation and improving LNA gain while maintaining noise performance, by calibrating and updating parameters based on feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If TX and RX share a common antenna with limited isolation, then device integration is improved, but TX leakage signal interferes with RX input causing saturation and reduced sensitivity
Solution Approach 1:
The patent captures the harmful TX leakage signal with a tap, processes it through adjustment circuits to match its characteristics, and then subtracts it from the RX input. This converts the harmful leakage into a useful compensation signal that actively cancels the interference, allowing the system to maintain both integration and isolation.
Solution Approach 2:
The patent introduces an intermediary leakage compensation circuit between the TX leakage path and the RX input. This circuit includes a tap to capture the leakage, adjustment circuits to match amplitude and phase, and a subtraction mechanism to cancel the interference, effectively mediating the conflict between shared antenna integration and signal isolation.
2Object-affected harmful factors
If additional isolation components are added to reduce TX leakage, then leakage compensation is improved, but device complexity and resource usage increase
Solution Approach 1:
The patent merges the leakage compensation function with the existing RX signal path by subtracting the compensated leakage signal at the RX input. This combines multiple functions (leakage capture, adjustment, and cancellation) into a single integrated process that doesn't require separate isolation components, reducing overall device complexity while maintaining effective compensation.
3Object-affected harmful factors
If RX components are designed for high linearity to handle TX leakage, then leakage resistance is improved, but manufacturing precision and cost increase
Solution Approach 1:
The patent applies preliminary anti-action by capturing the TX leakage signal before it reaches the RX components and actively canceling it through the compensation circuit. This prevents the leakage from reaching the RX front-end components in the first place, eliminating the need for them to be designed with high linearity specifications and reducing manufacturing precision requirements and costs.
Data Source
AI summary
A leakage compensation circuit includes a compensation digital to analog converter (DAC) and an adjustment circuit. The compensation DAC is configured to: receive a first digital signal associated with a transmitter of a transceiver; generate a compensation analog signal using the first digital signal; and provide the compensation analog signal to a receiver of the transceiver. The adjustment circuit is configured to generate the first digital signal by adjusting a second digital signal from the transmitter based on one or more adjustment parameters.