Antenna Switch Biasing for RF Linearity
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Solution Overview
Problem
Current antenna switches in radio frequency modules face challenges in reducing high-order harmonic distortion and intermodulation distortion (IMD) as the circuit scale increases, particularly with the introduction of W-CDMA systems, which require higher linearity and wider frequency bands, leading to increased distortion due to nonlinear elements and off-state devices.
Innovation Solution
A semiconductor integrated circuit device configuration is implemented where bias voltage is supplied to multiple signal nodes via resistive elements, allowing transistors in an off state to enter a deeper off state and operate in a region with low nonlinearity, reducing high-order harmonic distortion and IMD. This is achieved by coupling resistive elements in parallel to signal nodes, increasing the antenna voltage and reducing the influence of resistive elements on distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the circuit scale of antenna switch is increased to support multi-bands and multi-modes, then the adaptability and functionality are improved, but the high-order harmonic distortion and intermodulation distortion increase
Solution Approach 1:
The antenna switch circuit is divided into multiple stages, with each stage handling specific signal routing functions. This segmentation allows the circuit to support multiple bands and modes while distributing the distortion generation across isolated stages, reducing overall harmonic and intermodulation distortion.
Solution Approach 2:
Different stages of the antenna switch are designed with optimized local characteristics tailored to specific frequency bands and signal types. Each stage uses transistors and matching circuits optimized for its specific function, improving linearity and reducing distortion in each local section while maintaining overall multi-band capability.
2Use of energy by moving object
If transistors are operated in off state to reduce power consumption, then energy efficiency is improved, but nonlinear effects and distortion increase
Solution Approach 1:
Bias voltage is applied to transistors in advance to pre-establish optimal operating points before signal transmission begins. This preliminary biasing ensures transistors operate in linear regions during active states while maintaining low power consumption during idle states, preventing nonlinear distortion from occurring in the first place.
Solution Approach 2:
The bias voltage parameters are dynamically adjusted based on operating conditions, signal strength, and frequency band. By changing bias parameters adaptively, the transistor operating point is optimized to minimize distortion while maintaining low power consumption, allowing the system to switch between power-efficient off states and high-performance linear states as needed.
Data Source
AI summary
The present invention provides a semiconductor integrated circuit device and a radio frequency module realizing reduction in high-order harmonic distortion or IMD. For example, a so-called antenna switch having a plurality of transistors between an antenna terminal and a plurality of signal terminals is provided with a voltage supply circuit. The voltage supply circuit is a circuit for supplying voltage from a voltage supply terminal to at least two signal terminals in the plurality of signal terminals via resistive elements. With the configuration, antenna voltage dropped due to a leakage or the like can be boosted and, for example, transistors in an off state can be set to a deep off state.