A phase calibration methodology for accurate modulated measurements

Abstract

To address the challenge of the phase calibration of modulated RF and microwave signals or the response of a linear or nonlinear system under modulated excitation, a nextgeneration comb generator is characterized. The latter allows kHz-level modulation tones in addition to the GHz-level RF and microwave tones, while still exhibiting an acceptable power level for each tone. This comb generator includes a PRBS generator, two dividers and a logical "and" operation to trigger the internal pulse generating unit. The pulse generator is characterized using a calibrated sampling oscilloscope. Depending upon the mode of operation this generator could be operated using a plentitude of possible values for every setting (input frequency, divider value, PRBS length). Each setting results in a different amplitude and phase spectrum. In practice it is impossible to characterize this pulse generator and provide a spectral phase dataset for every possible setting of each mode. To address this problem it is investigated if it is feasible to mathematically obtain the complete amplitude and phase spectrum of each possible setting by just using the characterized information of a single pulse. The amplitude and phase characteristic obtained by the measured and predicted spectrum are analyzed and compared. In this paper this technique will be applied to a comb generator operating under divider or PRBS mode.

Asynchronous electro-optic sampling of all-electronically generated ultrashort voltage pulses

“…To demonstrate the usability of the ASOPS technique for the characterization of an electronic signal, a next-generation pulse generator [17,18] with a voltage amplitude of approximately −370 mV and a nominal bandwidth of 40 GHz is utilized. In figure 1, the experimental setup is shown.…”

“…These devices are important tools as they serve, e.g. as harmonic phase references [17,18] for the calibration of modulated RF and microwave signals. We show that an accurate time trace of the voltage pulse can be constructed from a large number of multiple measurements, which has several advantages.…”

Extension of NVNA Baseband Measurement for PA Characterization Under Complex Modulation

“…While the other one deals with multi-harmonic modulated components. According to the previous work in [5], [10], [11], [14], [16], and [17], potential solutions of the second signal can be chosen from using (i) pseudo-random binary sequence or chirp "triggered" comb generator and (ii) pulsed-RF or multisine driven step recovery diode (SRD) comb generator. Despite the detailed difference in impulse generation, the basic principle of all above solutions is to disturb the impulse train into a non-equally spaced one, so that modulated components at each harmonic band can be obtained.…”

Phase Offset Calibration in Multi-Channel Radio-Frequency Transceivers

“…For distributed commercial systems where PLL design flexibility is not available, robust phase calibration is required for multi-channel phase synchronization. Past works strived to compensate random phase offsets using nonlinear vector network analyzer (NVNA) test benches, where indirect compensation was achieved by accurate wideband calibration routines using phase references [5], [6], [7]. Direct cancellation techniques for random phase offsets were recently proposed without using phase references [3], [8].…”