RF Power Amplifier Test Apparatus Using Signal Inversion
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Solution Overview
Problem
Conventional digital predistortion testing of RF power amplifiers is time-consuming due to the need for serial downloads of predistorted waveforms to each device under test, leading to high test time efforts and reduced throughput in multi-site testing, especially when devices exhibit deviations caused by production tolerances or parasitic effects.
Innovation Solution
A test apparatus and method that corrects the response signal of the device under test using adaptive correction functions, eliminating the need for individual predistortion and waveform uploads by predicting the expected response to a predistorted signal, thereby reducing test time and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital predistortion testing is performed using conventional two-step method with serial downloads of predistorted waveforms to each DUT, then measurement precision of device non-linearity is improved, but loss of time increases significantly
Solution Approach 1:
Instead of predistorting the input waveform and measuring the output (conventional approach), the invention inverts the process by measuring the actual device response and computationally inverting it to obtain the predistorted response. This reversal eliminates the need for serial waveform downloads while maintaining measurement precision.
Solution Approach 2:
The invention replaces the mechanical/physical process of serial waveform downloads and re-uploads with a computational/mathematical process. By using mathematical inversion of the measured response, the system eliminates the time-consuming physical data transfer steps while achieving the same measurement objective.
2Manufacturing precision
If individual predistorted waveforms are downloaded and applied to each DUT in multi-site testing, then manufacturing precision of device performance evaluation is improved, but productivity decreases due to serial processing
Solution Approach 1:
The invention inverts the conventional testing sequence by first measuring all DUTs with standard waveforms in parallel, then computationally inverting the results to assess predistortion performance. This allows simultaneous processing of multiple DUTs rather than serial evaluation, dramatically improving throughput while maintaining evaluation precision.
Solution Approach 2:
The invention performs preliminary measurements of all DUTs using standard waveforms before the actual predistortion evaluation. By capturing the raw device responses first and then applying computational inversion, the system enables parallel processing of multiple devices while maintaining individualized evaluation accuracy.
3Measurement precision
If correction functions are applied to response signals to account for production tolerances and parasitic effects, then measurement precision is improved, but device complexity of the test system increases
Solution Approach 1:
The invention introduces correction functions as an intermediary computational layer between the raw device response and the final evaluation. These correction functions account for production tolerances and parasitic effects by mathematically adjusting the measured responses, thereby improving accuracy without requiring physical modifications to the test hardware.
Solution Approach 2:
The invention replaces complex physical calibration and compensation mechanisms with computational correction functions. Instead of using additional hardware to account for production variations and parasitic effects, the system uses mathematical models to correct the measured responses, reducing hardware complexity while maintaining measurement precision.
Data Source
AI summary
A test apparatus for testing a device under test is configured to receive a response signal from the device under test and to apply one or more correction functions to the received response signal to at least partially correct an imperfection of the DUT. The test apparatus is configured to thereby obtain a corrected response signal of the device under test and to evaluate the corrected response signal to judge the device under test.