Doherty Transceiver Circuit With TDD Harmonic Isolation
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Solution Overview
Problem
Doherty amplifiers used in transceiver circuits for wireless communication face challenges in maintaining high efficiency over a wide output power range and suffer from adjacent channel leakage due to high-order harmonic distortion, which affects reception sensitivity, especially in frequency division duplexing schemes.
Innovation Solution
Implementing a transceiver circuit with a Doherty amplifier and a low noise amplifier on a common package substrate, utilizing a time division duplexing scheme to switch between transmission and reception states, thereby isolating high-order harmonic distortion and preventing its impact on reception sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Doherty amplifier is used to maintain high efficiency over a wide output power range, then efficiency is improved, but high-order harmonic distortion increases causing adjacent channel leakage
Solution Approach 1:
The patent extracts and removes the harmful high-order harmonic components from the amplified signal using a filter circuit, while preserving the beneficial high efficiency characteristic of the Doherty amplifier. The filter is specifically designed to eliminate harmonic distortion that causes adjacent channel leakage.
Solution Approach 2:
The patent introduces a filter circuit as an intermediary component between the Doherty amplifier and the antenna. This intermediary element mediates by allowing the amplifier to operate efficiently while blocking the harmful harmonic components from being transmitted.
2Device complexity
If a common antenna is shared for transmit and receive in FDD scheme, then device complexity is reduced, but reception sensitivity deteriorates due to adjacent channel leakage
Solution Approach 1:
The patent converts the potentially harmful effect of using a common antenna (which could cause reception sensitivity deterioration) into a benefit by implementing the filter circuit that actively suppresses adjacent channel leakage. This allows the simple single-antenna configuration to maintain both low complexity and high reception sensitivity.
3Manufacturing precision
If digital pre-distortion system is applied to cancel distortion, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the complex digital pre-distortion system with a simpler, more straightforward filter circuit approach. Instead of using complex computational methods to cancel distortion, the invention uses a dedicated hardware filter that provides effective distortion cancellation with reduced processing complexity.
Data Source
AI summary
A Doherty amplifier including a main amplifier and a peak amplifier is mounted on a package substrate. A low noise amplifier is further mounted on the package substrate. A transmit/receive switch switches in terms of time between a transmission connection state in which an output signal of the Doherty amplifier is supplied to an antenna and a reception connection state in which a signal received by the antenna is inputted to the low noise amplifier.