Gate-Segmented RF Transmitter for High-Power Digital Modulation
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Solution Overview
Problem
Existing RF transmitters, particularly for high-speed and high-power applications like 5G mMIMO base stations, face challenges in achieving the required output power and efficiency due to limitations in digital transmitter (DTX) solutions, which are hindered by high parasitics, bandwidth restrictions, and inefficiencies in analog-intensive designs.
Innovation Solution
The implementation of a gate-segmented power output stage in RF transmitters, using a field-effect transistor with segmented gate fingers and drain fingers, combined with a digital driver for individual control of power output stage segments, allows for efficient switch-mode operation and reduced parasitics, enabling higher power levels and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital modulators are used to provide frequency agility and channel flexibility, then communication adaptability is improved, but output power is reduced due to low power consumption requirements
Solution Approach 1:
A dedicated power amplifier stage is introduced as an intermediary component between the digital modulator and the antenna. This separate amplifier boosts the low-power digital signal to high power levels without requiring the modulator itself to operate at high power, thus maintaining both communication adaptability and high output power capability
Solution Approach 2:
The transmitter is divided into functionally separate stages: a low-power digital modulator section for signal generation and frequency agility, and a high-power amplification section for power boosting. This segmentation allows each component to be optimized for its specific function without compromise
2Power
If power amplification is increased to achieve high power output, then output power is improved, but signal distortion increases due to non-linear operation
Solution Approach 1:
Traditional single-stage non-linear power amplification is replaced with a digital signal processing approach. Digital predistortion algorithms pre-compensate the signal to counteract anticipated non-linear distortion, and digital feedback loops continuously adjust parameters to maintain signal fidelity while operating at high power levels
Solution Approach 2:
The system dynamically adjusts amplification parameters and operating conditions based on real-time signal characteristics and feedback. By changing parameters such as gain, compression ratios, and distortion compensation factors, the system maintains high output power while minimizing signal distortion through adaptive control
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
An RF transmitter (1) having a gate-segmented power output stage (2) and a digital driver (5). The gate-segmented power output stage (2) includes a field-effect transistor with a plurality of gate fingers (32) and drain fingers (31) that define a gate periphery. The field-effect transistor comprises a plurality of power output stage segments (3) that each correspond to a respective part of the gate periphery, and that each have a respective power output stage segment input (4). The digital driver (5) has control outputs (6) which are connected to corresponding ones of the respective power output stage segment inputs (4), and is configured for individually switching each of the power output stage segments (3) between an on mode and a cut-off mode in dependence of one or more input signals to obtain a modulated RF carrier signal at an output (7) of the gate-segmented power output stage (2).