4-Channel, time-domain measurement system using track and hold amplifier for the characterization and linearization of high-power amplifiers

Abstract

International audienceWe propose in this paper a 4-channel time-domain test bench for the characterization and linearity enhancement of microwave power amplifiers (PAs). The proposed time-domain measurement system utilizes four track and hold amplifiers (THAs) for direct subsampling of radiofrequency (RF) signals. The use of wideband THAs to replace samplers or mixers enables reducing analog IF circuit complexity. It permits direct digitization of RF signals like CW, two-tone and pulsed modulated signals, bringing more flexibility in the receiver's performance by enhancing the dynamic range and bandwidth. This test bench is capable of completely extracting the phase, amplitude, and transfer characteristics of non-linear devices excited with CW or modulated RF signals. In this work, two-tone transfer characteristics of a 50 W GaN HEMT Nitronex PA were extracted and processed for applying digital pre-distortion linearization to enhance linearity performance. Time-domain envelope and carrier waveforms (voltage and current) along with third-order inter-modulation distortion (IMD) products with and without digital pre-distortion scheme are also presented

Time-domain interleaved high sampling rate system for large signal characterization of non-linear devices

“…This is where this measurement system is different to the one described in [2], [3], [4]. In [2] sub-sampling technique was used to down convert the RF signal and then sampled at four times the IF frequency. The in phase and quadrature components were computed and the phase and amplitude envelope (Fig.…”

“…To observe these transient characteristics time-domain measurement approach is the only solution to retrieve sufficient information Many time-domain measurement systems based on different techniques have been developed in the past. All these systems translate the fundamental radio spectra into intermediate frequency spectra using sampler based [1], mixer based or most recently Track and Hold Amplifier (THA) [2], [3] based approach. THA based time-domain measurement system applies direct voltage sampling technique [2] compared to charge sampling technique [2] used in samplers.…”

“…All these systems translate the fundamental radio spectra into intermediate frequency spectra using sampler based [1], mixer based or most recently Track and Hold Amplifier (THA) [2], [3] based approach. THA based time-domain measurement system applies direct voltage sampling technique [2] compared to charge sampling technique [2] used in samplers. The use of continuous sinusoidal clock in contrast to pulsed strobe signal in samplers, reduce the circuit complexities and completely eradicate the IF circuitry.…”