A wideband 20 to 28 GHz signal generator MMIC with 30.8 dBm output power based on a power amplifier cell with 31% PAE in SiGe

High-frequency systems such as mm-wave radar transmitters and LO/RF driver chains in vector network analyzers (VNAs) often require the generation of signals with high output power. While these systems benefit considerably from the reduction in size and cost provided by SiGe integration, their output power must be further increased in order to meet the performance of other technologies (e.g., GaAs). To this end, a SiGe signal generator MMIC was developed that achieves 28.7 dBm peak output power with 21.9% PAE and over 27.4 dBm of output power over the whole frequency range from 19.7 GHz to 28.2 GHz. The output power is scalable with DC current up to a maximum of 30.8 dBm. The signal generator is based on a VCO, power amplifier cells (PA cells) and lumped-element Wilkinson power combiners/dividers. The VCO's phase noise is less than -96 dBc/Hz at 1 MHz offset over the entire frequency range. The developed single PA cell achieves a maximum saturated output power Psat of 24.7 dBm with peak PAE of 31%. This article describes the design and performance of all components. The signal generator MMIC has been integrated in an evaluation board together with a PLL, power supply, and serial interface

Modeling Approaches for Active Antenna Transmitters

The rapid growth of data traffic in mobile communications has attracted interest to Multiple-Input-Multiple-Output (MIMO) communication systems at millimeter-wave (mmWave) frequencies. MIMO systems exploit active antenna arrays transmitter configurations to obtain higher energy efficiency and beamforming flexibility. The analysis of transmitters in MIMO systems becomes complex due to the close integration of several antennas and power amplifiers (PAs) and the problems associated with heat dissipation. Therefore, the transmitter analysis requires efficient joint EM, circuit, and thermal simulations of its building blocks, i.e., the antenna array and PAs. Due to small physical spacing at mmWave, bulky isolators cannot be used to eliminate unwanted interactions between PA and antenna array. Therefore, the mismatch and mutual coupling in the antenna array directly affect PA output load and PA and transmitter performance. On the other hand, PAs are the primary source of nonlinearity, power consumption, and heat dissipation in transmitters. Therefore, it is crucial to include joint thermal and electrical behavior of PAs in analyzing active antenna transmitters. In this thesis, efficient techniques for modeling active antenna transmitters are presented. First, we propose a hardware-oriented transmitter model that considers PA load-dependent nonlinearity and the coupling, mismatch, and radiated field of the antenna array. The proposed model is equally accurate for any mismatch level that can happen at the PA output. This model can predict the transmitter radiation pattern and nonlinear signal distortions in the far-field. The model\u27s functionality is verified using a mmWave active subarray antenna module for a beam steering scenario and by performing the over-the-air measurements. The load-pull modeling idea was also applied to investigate the performance of a mmWave spatial power combiner module in the presence of critical coupling effects on combining performance. The second part of the thesis deals with thermal challenges in active antenna transmitters and PAs as the main source of heat dissipation. An efficient electrothermal modeling approach that considers the thermal behavior of PAs, including self-heating and thermal coupling between the IC hot spots, coupled with the electrical behavior of PA, is proposed. The thermal model has been employed to evaluate a PA DUT\u27s static and dynamic temperature-dependent performance in terms of linearity, gain, and efficiency. In summary, the proposed modeling approaches presented in this thesis provide efficient yet powerful tools for joint analysis of complex active antenna transmitters in MIMO systems, including sub-systems\u27 behavior and their interactions

A review of technologies and design techniques of millimeter-wave power amplifiers

his article reviews the state-of-the-art millimeter-wave (mm-wave) power amplifiers (PAs), focusing on broadband design techniques. An overview of the main solid-state technologies is provided, including Si, gallium arsenide (GaAs), GaN, and other III-V materials, and both field-effect and bipolar transistors. The most popular broadband design techniques are introduced, before critically comparing through the most relevant design examples found in the scientific literature. Given the wide breadth of applications that are foreseen to exploit the mm-wave spectrum, this contribution will represent a valuable guide for designers who need a single reference before adventuring in the challenging task of the mm-wave PA design