RF Transmitter Bias Voltage Control for Lower Power Consumption
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Solution Overview
Problem
Wireless communication transmitters face challenges in power efficiency due to voltage headroom reduction and increased power consumption, especially when transmitting RF signals across various protocols and frequency ranges, which limits output power and increases energy usage.
Innovation Solution
The implementation of a digital voltage-controlled attenuator (DVCA) and voltage-to-current converters, along with multiple current sources and bias voltage adjustment mechanisms, allows for dynamic power control and reduced power consumption by optimizing voltage headroom and current usage across different transmission protocols and frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a drive amplifier or gain stage is used to increase the power of the transmitted signal, then the transmitted signal power is improved, but the power consumption of the transmitter increases
Solution Approach 1:
The patent implements dynamic voltage headroom adjustment by detecting the output power level of the RF signal and accordingly adjusting the voltage headroom provided to the power amplifier. When output power is low, less voltage headroom is provided, reducing power consumption. When output power is high, more voltage headroom is provided to maintain signal quality. This dynamic adjustment resolves the contradiction between maintaining transmitted signal power and reducing power consumption.
2Power
If bias voltage is increased to drive transmitter components, then the voltage headroom is improved, but current sinking through internal resistances increases power consumption
Solution Approach 1:
The patent changes the voltage headroom parameter dynamically based on the detected output power level of the RF signal. By adjusting the voltage headroom parameter to match the actual transmission requirements, the system avoids maintaining high voltage headroom during low-power transmission, thereby reducing current sinking through internal resistances and lowering overall power consumption while maintaining adequate voltage headroom when needed.
3Reliability
If voltage headroom is increased to maintain transmitter performance, then the performance is improved, but the output power is limited due to increased power consumption
Solution Approach 1:
The patent employs dynamic adjustment of voltage headroom based on real-time detection of RF signal output power. This allows the transmitter to provide high voltage headroom only when high output power is required, and reduce voltage headroom during low-power transmission modes. Consequently, the system maintains transmitter performance reliability when needed while enabling higher output power capability without the penalty of continuously high power consumption that would otherwise limit output power.
Data Source
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AI summary
In accordance with some embodiments of the present disclosure, a circuit comprises a balun (234) configured to receive a radio frequency (RF) signal at a first input port and a second input port of an input coil (236). The balun (234) is further configured to output the RF signal at an output coil (238) communicatively coupled to the input coil. The circuit also comprises a supply voltage selector circuit (240) coupled to the input coil and configured to adjust a bias voltage at the input coil (236) according to a power level of the RF signal received at the input coil. (236)