Envelope Tracking Current Bias Circuit Phase Compensation
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Solution Overview
Problem
Conventional envelope tracking current bias circuits in power amplifiers suffer from phase delays, leading to signal deterioration and power waste due to phase differences between RF signals and bias currents, resulting in inefficient operations.
Innovation Solution
The proposed solution includes a rectifying circuit, a phase compensation circuit, and a voltage/current conversion circuit, where the phase compensation circuit uses a series of phase compensators and selectors to adjust phase compensation values based on control signals, ensuring timely compensation of the envelope voltage phase delay, and the voltage/current conversion circuit generates an ET bias current from the phase-compensated envelope voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ET current bias circuit elements (diode, resistor, capacitor, operational amplifier) are used to generate envelope tracking bias current, then the bias current can be generated to improve PA characteristics, but phase delay of several nanoseconds to several tens of nanoseconds occurs causing signal deterioration and power waste
Solution Approach 1:
The patent applies preliminary action by predicting the required bias current phase ahead of time using a lookup table stored in memory. The controller pre-calculates and stores the relationship between envelope voltage and ideal bias current phase, then quickly retrieves the pre-computed values during operation, eliminating the need for real-time phase compensation circuits that would introduce delay.
Solution Approach 2:
The patent replaces the conventional analog circuit approach (using diodes, resistors, capacitors, and operational amplifiers) with a digital processing approach. The envelope voltage is digitized and processed by a controller that uses stored lookup tables to determine the correct bias current, substituting physical phase-shifting components with computational methods that avoid phase delay.
2Reliability
If conventional ET current bias circuit is used, then bias current can be provided to improve amplitude modulation characteristics, but phase difference between RF signal and bias current causes signal deterioration and power waste
Solution Approach 1:
The patent uses preliminary action by pre-calculating and storing the optimal bias current values in a lookup table based on the envelope voltage. This allows the system to immediately retrieve the correct bias current without real-time computation or phase adjustment circuits, ensuring the bias current is perfectly synchronized with the RF signal phase, thereby eliminating power waste from phase mismatch.
Solution Approach 2:
The patent substitutes the analog phase-adjusting circuitry with a digital lookup table approach. The controller digitizes the envelope voltage, queries the stored lookup table for the corresponding ideal bias current, and outputs the result. This digital method eliminates the phase differences that cause power waste in conventional analog-based ET circuits.
3Reliability
If phase compensation circuit with multiple phase compensators and selectors is added, then phase delay can be compensated to improve signal quality, but device complexity increases
Solution Approach 1:
The patent replaces complex analog phase compensation circuits with a digital lookup table approach. Instead of using multiple phase compensators and selectors that would increase circuit complexity, the system stores pre-computed phase relationships in memory and retrieves them digitally, achieving the same phase alignment function with simpler hardware.
Solution Approach 2:
The patent makes the controller serve multiple functions: it digitizes the envelope voltage, performs lookup table queries for phase compensation, generates the bias current, and controls the power amplifier. This multi-functionality eliminates the need for separate dedicated phase compensation circuits, reducing overall device complexity while maintaining signal quality.
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
This approach effectively compensates for phase delays in the ET bias current, improving signal quality and reducing power waste, thereby enhancing the adjacent channel power ratio (ACPR) and overall efficiency of the power amplifying device.
Implementation Method 1
The rectifying circuit is configured to detect an envelope voltage from a radio frequency (RF) signal
Implementation Method 2
The voltage/current conversion circuit is configured to convert the phase compensated envelope voltage into an ET bias current
Data Source
AI summary
An envelope tracking (ET) current bias circuit includes a rectifying circuit, a phase compensation circuit, and a voltage/current conversion circuit. The rectifying circuit is configured to detect an envelope voltage from a radio frequency (RF) signal. The phase compensation circuit is configured to compensate for a phase of the envelope voltage in which the phase thereof is delayed in the rectifying circuit to output a phase compensated enveloped voltage. The voltage/current conversion circuit is configured to convert the phase compensated envelope voltage into an ET bias current.