Time-domain envelope measurements for characterization and behavioral modeling of nonlinear devices with memory

Abstract

Abstract-This paper presents a calibrated four-channel measurement system for the characterization of nonlinear RF devices such as power amplifiers. The main goal of this study is to perform the characterization of the bandpass response of a nonlinear device-under-test (DUT) driven by modulated carriers. The proposed setup enables the generation of -o r -band (1-4 GHz) carriers with a modulation bandwidth up to 100 MHz. The carrier harmonics generated by the nonlinear DUT are ignored and considered to be sufficiently filtered. This characterization setup enables calibrated time-domain measurements of the complex envelopes of both incoming and outgoing RF waves at the input and output of the DUT. This means that the fundamental and harmonic frequencies of the envelope are measured and processed. A large set of modulation formats can be generated by using a computer-controlled arbitrary waveform generator. Complex envelopes are measured by using a four-channel sampling scope. The proposed calibrated setup can be used to study or to validate linearization techniques of power amplifiers. This characterization tool is also well suited for the extraction and validation of behavioral bilateral models of nonlinear RF analog equipment exhibiting memory effects.

Comparison of evaluation criteria for power amplifier behavioral modeling

“…The spectra of the measured input and output signals, model output PH (13,4) and PH (9,2) and the crossvalidation errors when using PH (13,4), PH(13,0) and PH(9,2) models are shown in Fig. 4.…”

“…Outof-band performance varies more, with the highest model order showing the best performance. The importance of memory effects is illustrated by the performance difference between PH(13,0) and PH (9,2).…”

On the use of multi-tone for the measurement of noise power ratio distortion in RF circuits

“…The test signal is directly converted to test frequency (250 kHz~6GHz, with option 506) by E4438C, so this NPR test setup does not need any up-conversion circuits and the LO leakage rejection loops in [7][8][9][10]. Because the total input power of test signal can be directly configured by E4438C which has a large output power range, the high linearity amplifier and computer controlled attenuator in [7][8][9][10] are also eliminated. Two step attenuators connected before and after the DUT are used to improve the impedance mismatch between DUT and instruments.…”

“…High performance bandpass and notch filters are necessary to remove a noise slice generated by the analog white noise source [6][7] in traditional NPR measurement setup. A novel NPR measurement method based on a high performance baseband arbitrary waveform generator (AWG) [8][9][10] is developed by Reveyrand et al They use the calibrated timedomain envelope measurement system to character the nonlinear device. But a great number of tones (≥ 10000) are required for steady measurement results [7][8][9][10].…”

Nonlinear network analysis for modern communication devices and systems

“…However, either by proper selection of the frequency band or using |S 21 | measurement, variations in the insertion loss can be neglected or compensated for. Similar approaches to calibrate new setups have been developed based on use of the LSNA as a reference instrument [9].…”