Power Amplifier Evaluation Using Stepwise RF Input Levels
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Solution Overview
Problem
Existing power amplifier evaluation methods require a long measurement time due to the need to sweep the power of the radio frequency input signal for each power supply voltage, making it inefficient for characterizing power amplifiers.
Innovation Solution
A power amplifier evaluation method that modulates a radio frequency signal with a constant amplitude using a digital modulation signal to generate a radio frequency input signal with stepwise amplitude changes, allowing for measurement of the power amplifier's output in multiple measurement periods with different signal amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power of a radio frequency input signal is swept for each power supply voltage to evaluate power amplifier characteristics, then comprehensive measurement data is obtained, but the measurement time becomes long
Solution Approach 1:
The patent segments the measurement process by dividing it into a calibration phase and an evaluation phase. During calibration, a vector signal analyzer measures and stores amplitude correction values for different frequency points. During evaluation, these pre-stored values are applied to directly calculate output power without repeated sweeping, thus obtaining comprehensive data efficiently
Solution Approach 2:
The patent performs preliminary calibration measurements to establish amplitude correction values before the actual power amplifier evaluation. This preliminary action creates a lookup table of correction factors that can be rapidly applied during subsequent measurements, eliminating the need to perform time-consuming sweeps during the main evaluation phase
2Measurement precision
If the amplitude of a radio frequency input signal is changed by sweeping the oscillator amplitude, then the input power is varied, but the measurement time increases
Solution Approach 1:
The patent replaces the mechanical sweeping method with a digital calculation approach. Instead of physically sweeping the oscillator amplitude, the system uses pre-measured amplitude correction values stored in memory and applies them through digital computation to determine output power at different input power levels, significantly accelerating the measurement process
Solution Approach 2:
The patent changes the measurement approach from physically varying oscillator amplitude to using calculated amplitude correction values. By storing correction factors for different frequency points and applying them digitally, the system achieves rapid input power variation without the time penalty of mechanical sweeping
Data Source
AI summary
A radio frequency signal having a constant amplitude is modulated by a digital modulation signal and a radio frequency input signal whose amplitude changes stepwise is generated. The radio frequency input signal is input into a power amplifier that is an evaluation target. A period in which an amplitude of the radio frequency input signal is constant is defined as a measurement period and an output signal of the power amplifier is measured in each of measurement periods in which amplitudes of the radio frequency input signal are different from each other.