Multiple Power RF Transmitter for Multi-Standard Wireless
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Solution Overview
Problem
Existing RF transmitters face challenges in supporting multiple communication standards with a common antenna, leading to increased costs and inefficiencies due to the need for separate circuitry and high resistive losses, especially at high power levels.
Innovation Solution
A multiple power RF transmitter design that combines low-power and high-power amplification circuits with an integrated balun, using low- and high-voltage CMOS transistors, and a programmable frequency synthesizer to support various modulation techniques and carrier frequencies, reducing the need for additional baluns and enhancing second harmonic attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate circuitry is provided for each communication standard, then each standard can be supported with optimal characteristics, but product cost increases
Solution Approach 1:
The patent implements a universal transmitter architecture where a single RF transmitter circuit supports multiple communication standards (WiFi, Bluetooth, ZigBee, NFC) through software-defined radio techniques. The transmitter uses a common phase-locked loop (PLL) and numerically controlled oscillator (NCO) to generate carrier signals for different standards, and employs standard modulation schemes (QPSK, OQPSK, GFSK) that can be configured via software to match different protocol requirements. This multi-functional approach allows one hardware platform to replace what would traditionally require separate dedicated transmitters for each standard, thereby reducing product cost while maintaining support for multiple communication protocols
Solution Approach 2:
The patent utilizes parameter changes in the RF signal generation process to adapt to different communication standards. By dynamically adjusting parameters such as carrier frequency, modulation index, symbol rate, and power level through software control, the same hardware transmitter can optimize its output characteristics for different protocols. For example, the NCO allows precise frequency and phase modulation to match WiFi's 2.4 GHz or Bluetooth's requirements, while the power amplifier can be controlled to provide appropriate output levels for near-field communication versus longer-range wireless LAN applications
2Device complexity
If a common antenna is used for multiple standards, then device complexity is reduced, but it becomes difficult to design low-cost reliable transmitters with acceptable characteristics
Solution Approach 1:
The patent employs dynamic signal processing techniques to maintain reliable transmitter characteristics across multiple standards using a common antenna. The system dynamically adjusts modulation parameters, power levels, and frequency synthesis based on the active communication standard. The software-controlled architecture allows real-time optimization of signal characteristics to match the specific requirements of each protocol, ensuring acceptable performance whether transmitting WiFi signals at higher power levels or Bluetooth low-energy signals at lower power levels, all through the same antenna interface
Solution Approach 2:
The implementation incorporates feedback mechanisms through the phase-locked loop (PLL) and automatic gain control systems that monitor and adjust the RF output in real-time. This feedback ensures that the transmitter maintains stable frequency and amplitude characteristics across different operating conditions and communication standards, compensating for variations in antenna impedance and signal loading that occur when switching between WiFi, Bluetooth, and other protocols
3Power
If high power transmission is implemented, then transmission distance is improved, but resistive losses increase significantly
Solution Approach 1:
The patent implements parameter changes in the power amplification stage to optimize the trade-off between transmission power and resistive losses. The system uses variable gain amplifiers and software-controlled power management to adjust the output power level according to the specific communication standard and environmental conditions. For near-field communication applications, the transmitter operates at low power levels to minimize resistive losses in the antenna and matching network, while for extended-range WiFi applications, it dynamically increases power output only when necessary, thereby reducing overall energy loss while maintaining adequate transmission distance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables flexible operation across different transmission standards with reduced costs and losses, achieving efficient power transmission and harmonic attenuation, suitable for a wide range of applications using low-cost CMOS technology.
Implementation Method 1
a balanced-unbalanced transformer (balun), and first and second amplification circuits. The balun has a primary side adapted to be coupled to an antenna, and a secondary side. The first amplification circuit has an input coupled to the RF signal source, and an output coupled to the primary side of the balun.
Implementation Method 2
The first amplification circuit has an input coupled to the RF signal source, and an output coupled to the primary side of the balun. The second amplification circuit has an input coupled to the RF signal source, and an output coupled to the secondary side of the balun. The second amplification circuit has a higher output power than the first amplification circuit.
Data Source
AI summary
In one form, a radio frequency (RF) transmitter includes an RF signal source, a balanced/unbalanced transformer (balun), and first and second amplification circuits. The balun has a primary side adapted to be coupled to an antenna, and a secondary side. The first amplification circuit has an input coupled to the RF signal source, and an output coupled to the primary side of the balun. The second amplification circuit has an input coupled to the RF signal source, and an output coupled to the secondary side of the balun. The second amplification circuit has a higher output power than the first amplification circuit.