Mm-wave PAs Research Articles

Deep Learning-Enabled Inverse Design of 30–94 GHz Psat,3dB SiGe PA Supporting Concurrent Multiband Operation at Multi-Gb/s

Deep learning and artificial intelligence, in general, is advancing scientific discovery and technological inventions through its ability to extract inherently hidden features and map it to output in a highly complex multi-dimensional space. Synthesis of electromagnetic (EM) structures with nearly arbitrary with desired functional properties is such an example of a high dimensional optimization space. In this article, we employ deep convolutional neural network (CNN) to allow robust and rapid prediction of scattering properties of nearly arbitrary planar electromagnetic structures on chip. Utilizing this, the work reports an mm-wave PA in 90-nm SiGe with a novel deep learning-enabled inverse design of low-loss, broadband output matching network that achieves a PAE of 16%–24.7%, a saturation power of 16.7–19.5 dBm across P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat, 3 dB</sub> bandwidth of 30–94 GHz (103.2%), while supporting both single-carrier high-speed modulation and concurrent multiband multi-Gb/s non-constant amplitude modulation. The P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat, 3 dB</sub> bandwidth covers from 5G band up to W-band and is higher than all reported mm-wave silicon PAs which have peak PAE > 20% and demonstrates for the first time concurrent multiband (triple-band) transmission with superior performance at multi-Gb/s.

A Compact SiGe Stacked Common-Base Dual-Band PA With 20/18.8 dBm P sat at 36/64 GHz Supporting Concurrent Modulation

This work presents a compact, concurrent dual-band (36/64 GHz) linear power amplifier in 90 nm SiGe technology. To simultaneously overcome the gain and power limitation of conventional common-emitter (CE) silicon device at mm-wave, the stacked common-base (SCB) topology in SiGe is studied and utilized as PA cell. A highly efficient dual-band output network enables the optimum load-line matching for two widely separated frequencies. The proposed PA achieves 20/18.8 dBm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {sat}}$ </tex-math></inline-formula> , 25/22.5% PAE at 36/64 GHz supporting two concurrent 32 QAM signals (total data rate of 9 Gb/s) with 9.5/7.8 dBm linear average power respectively, and concurrent PAE of 8.9%. To the best of the authors’ knowledge, this prototype achieves highest dual frequency output power, PAE, and one of the first concurrent dual-band modulation among silicon-based mm-wave PAs, while still maintaining a highly compact footprint.

Improved behavioral modeling using augmented LSTM networks for ultra‐broadband mmWave PA

AbstractIn this article, a new behavioral modeling method based on augmented long‐short term memory (ALSTM) networks for ultra‐broadband millimeter‐wave power amplifiers (mmWave PAs), is proposed. The basic theory and modeling procedure of this technique are provided. Different optimization cores of the models are tested, and the optimal algorithm is chosen. Tradeoffs have been made to fix the optimal topology for the proposed modeling technique. To validate the proposed method, a 4‐carrier 320 MHz modulated signal was employed to excite a mmWave PA with the center frequency located at 41 GHz. Experimental results show that the proposed ALSTM model has better predictive capability when compared with the traditional and other existing machine learning modeling techniques.

Wideband millimetre‐wave CMOS power amplifier using transistor‐based inductive source degeneration and specially shielded transformer

This study presents integration of transistor based inductive source degeneration and specially shielded transformer into a millimetre-wave power amplifier (mm-wave PA) operating at wideband. A new configuration of high Q distributed inductor is devised and embedded in CMOS transistor source to enhance stability, maximum stable gain and bandwidth of mm-wave CMOS PAs. The source inductance selection is conveniently investigated by the proposed admittance matrix condensation. In power splitting and combining part, a novel X-shape pattern-ground shielding is inserted in high turn ratio transformer to ameliorate wideband matching. Based on these techniques, a fully differential mm-wave PA was implemented in 65 nm low-power CMOS with 0.25 mm2 core area. The measurement results show that its differential drive gain and common mode rejection ratio are above 10 and 26 dB, respectively, in a wide frequency range of 41 to 61 GHz, while the power added efficiency (PAE) is still above 10.8% at 46–62 GHz. This CMOS PA also achieves 11.9 dBm output referred 1-dB compression point (P 1 dB) and 15.2 dBm saturated power (P sat) with 12.4% peak PAE.

A 40–67 GHz Power Amplifier With 13 dBm ${\rm P}_{\rm SAT}$ and 16% PAE in 28 nm CMOS LP

Pushed by the availability of large fractional bandwidths, many well-established applications are focusing mm-wave spectrum for product deployment. Generation of broadband power at mm-waves is challenging because a key target such as the efficiency trades with the gain-bandwidth (GBW) product. The major limit is the capacitive parasitics at the interstage between driver and power devices. The latter are designed with a large form factor so as to deliver the desired output power and are commonly biased in class-AB to achieve high drain efficiency, penalizing GBW. In this paper, a design methodology for interstage and output matching networks targeting large fractional bandwidth and high efficiency is proposed. Leveraging inductively coupled resonators, we apply Norton transformations for impedance scaling. In both networks, topological transformations are employed to include a transformer, achieve the desired load impedance and minimize the number of components. A two-stage differential PA with neutralized common source stages has been realized in 28 nm CMOS using low-power devices. The PA delivers 13 dBm saturated output power over the 40–67 GHz bandwidth with a peak power-added efficiency of 16% without power combining. To the best of author's knowledge, the presented PA shows state-of-the-art performances with the largest fractional bandwidth among bulk CMOS mm-wave PAs reported so far.

A 1 V power amplifier for 81–86 GHz E-band

The design and layout of a two stage SiGe E-band power amplifier using a stacked transformer for output power combination is presented. In EM-simulations with ADS Momentum, at E-band frequencies, the power combiner consisting of two individual single turn transformers performs significantly better than a single 2:1 transformer with two turns on the secondary side. Imbalances in the stacked transformer structure are reduced with tuning capacitors for maximum gain and output power. At 84 GHz the simulated loss of the stacked transformer is as low as 1.35 dB, superseding the performance of an also presented alternative power combiner. The power combination allows for a low supply voltage of 1 V, which is beneficial since the supply can then be shared between the power amplifier and the transceiver, thereby eliminating the need of a separate voltage regulator. To improve the gain of the two-stage amplifier it employs a capacitive cross-coupling technique not yet seen in mm-wave SiGe PAs. Capacitive cross-coupling is an effective technique for gain enhancement but is also sensitive to process variations as shown by Monte Carlo simulations. To mitigate this two alternative designs are presented with the cross coupling capacitors implemented either with diode coupled transistors or with varactors. The PA is designed in a SiGe process with f T = 200 GHz and achieves a power gain of 12 dB, a saturated output power of 16 dBm and a 14 % peak PAE. Excluding decoupling capacitors it occupies a die area of 0.034 mm2.

Leveraging Integration: Toward Efficient Linearized All-Silicon IC Transmitters

Recent efforts in efficient linearized all-Si IC transmitters have produced a 7x increase in output power and a +15% increase in PAE (over the 2008 PAE state of the art of 20%) of integrated Si mm-wave PAs. A number of on-chip integrated, highly linear transmitter architecture approaches have been developed and demonstrated.