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This paper presents the design and experimental characterization of a power transfer system performing a dc–dc conversion with on-chip galvanic isolation. The converter is operated in the VHF band, which enables fully integration of all the required components in silicon technology. It consists of only two silicon dice, i.e., a power oscillator with an on-chip isolation transformer and a full-bridge rectifier, which are fabricated in 0.35–µm BCD and 0.13–µm CMOS technology, respectively. A thick SiO2 layer was used, which guarantees galvanic isolation between the transformer windings. A co-design procedure for the system building blocks is proposed, which aims at optimizing the dc–dc converter performance in terms of power efficiency at a given power density. Thanks to the adopted approach, a maximum output power up to 980 mW is demonstrated with a power efficiency of 29.6%. This paper outperforms previously reported integrated inductive step-up converters in terms of power per silicon area (up to 105 mW/mm2), while providing on-chip galvanic isolation without any discrete devices or post-processing steps. [ABSTRACT FROM PUBLISHER]

This article presents a 24/77-GHz transmitter chipset for automotive radar sensors implemented in a 160/175-GHz fT/fmax SiGe BiCMOS technology. The chipset adopts a dual-band architecture consisting of a 24-GHz section for ultra-wideband short-range radar operation, which is also exploited to drive the 77-GHz long-range radar transmitter front-end. The proposed design adopts a single 24-GHz frequency synthesizer to implement both radar operation modes. The transmitter chipset is able to deliver a maximum output power of 3 dBm and 12 dBm at 24 GHz and 77 GHz, respectively. The 24-GHz transmitter demonstrates to operate with pulse widths of 0.5 ns and 1 ns in compliance with the transmission mask designed by ETSI. The 77-GHz transmitter exhibits a power gain of 20 dB, an output power of 12 dBm, and an output referred 1-dB compression point of 9.5 dBm, while drawing 155 mA from a 2.5-V supply voltage. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:782-786, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27425 [ABSTRACT FROM AUTHOR]

This paper presents a Colpitts-based voltage-controlled oscillator (VCO) for W-band radar applications. In the proposed circuit, the oscillation signal is directly drawn from the switching transistor bases by means of the primary winding of a transformer tank, while the secondary winding drives the output buffer. This solution improves both tuning range and oscillation swing with respect to traditional millimeter-wave VCO topologies without increasing power supply. The oscillator is implemented in a 0.13-\mu\ m SiGe BiCMOS technology, along with high-frequency dividers to enable low-frequency testing. The VCO exhibits a phase noise of -\99.3 dBc/Hz at 1-MHz offset from an oscillation frequency of 76 GHz and a tuning range of 4.9% with a consumption of 65 mW at 2.5-V power supply. The VCO is also used to drive a two-stage power amplifier in a fully integrated W-band transmitter that is able to deliver an overall output power as high as 15 dBm at 76 GHz. [ABSTRACT FROM AUTHOR]

This paper presents a pseudodifferential power amplifier for 77-GHz automotive radar. The circuit is fabricated in a SiGe HBT BiCMOS technology featuring bipolar transistors with fT/f\max of 230/280 GHz. The amplifier adopts a transformer-coupling current-reuse approach to improve both gain and efficiency. An interstacked transformer is also profitably adopted to reduce output losses due to the differential-to-single-ended conversion. The amplifier exhibits a saturated power, a peak power-added efficiency, and a gain of 14.5 dBm, 9%, and 25 dB, respectively, thus achieving a first-rate figure-of-merit as high as 4755. [ABSTRACT FROM PUBLISHER]

This paper presents a 15-dBm power amplifier for 77-GHz automotive radar applications, which is fabricated in a 0.13-\mu\ m SiGe:C BiCMOS process featuring bipolar transistors with f T / f\max of 230/280 GHz. The circuit consists of a two-stage pseudodifferential cascode with fully integrated input/output matching networks. State-of-art performance is achieved with the proposed design algorithm and layout optimization. The amplifier demonstrates a figure-of-merit of 2500 achieving a 22.5-dB power gain and a power-added efficiency of 7.5% at 77 GHz, while drawing 130 mA from a 2.5-V voltage supply. [ABSTRACT FROM AUTHOR]

This letter presents a 77-GHz power amplifier implemented in a SiGe BiCMOS technology featuring bipolar transistors with 160/175-GHz f/ f. The circuit adopts a two stage differential topology with integrated input/output matching networks. The amplifier performance is considerably improved thanks to proper input/output LC resonant networks, which cancel out the ground-plane parasitic effect. Matching networks use stacked transformers for impedance matching, differential-to-single-ended conversion, and electro-static discharge protection. The circuit achieves a power gain of 18.5 dB, a maximum output power of 11.6 dBm, with 4.2% power-added efficiency, and an output 1-dB compression point of 9.3 dBm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1413-1416, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25972 [ABSTRACT FROM AUTHOR]

In this letter, a novel structure for mm-wave integrated transformers is presented. The proposed transformers, namely, interstacked, exploit mixed interleaved/stacked coils, which allow increasing the magnetic coupling with respect to stacked devices, providing full geometrical/electrical symmetry. An extensive comparison between interstacked and conventional structures demonstrates the benefits of the proposed configuration in terms of the most significant figures of merit for integrated transformers. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2160–2163, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25385 [ABSTRACT FROM AUTHOR]

A lumped scalable model of silicon integrated inductors for RF IC design is presented. It was validated up to 20 GHz using measured performance parameters of more than 70 single-ended and differentially driven spirals covering 0.2- to 8.3 nH inductance values. Excellent accuracy, full geometrical scalability, compactness and high capability for implementation in circuit simulators promote the proposed model as a reliable time-saving design tool. Two circuital example, i.e., 5-GHz down-converter and 10-GHz VCO, are also presented to demonstrate its use in practical cases. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [ABSTRACT FROM AUTHOR]

In this article, a 24-GHz low-noise amplifier for vehicular short-range radar applications is presented. The circuit, fabricated in a 0.13-μm SiGe:C BiCMOS process, consists of three fully differential transformer-loaded cascode stages, including a gain-control functionality. The amplifier exhibits a 35-dB power gain and a noise figure of 3.4 dB, providing a reverse isolation better than -60 dB. By using a 1-bit gain control, the LNA achieves an input 1-dB compression point of -12 dBm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2013–2016, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23584 [ABSTRACT FROM AUTHOR]

An effective codesign approach for harvesting systems is described in this article, which is based on a CMOS differential-drive rectifier and an inductively coupled loop (ICL) antenna. The proposed approach acts on both the rectifier and the antenna and aims at optimizing the system performance in terms of efficiency and input sensitivity for a given load specification. Moreover, a rectifier solution is also proposed to enhance the circuit performance by properly driving the transistor bulks without additional components. An RF harvesting system operating at 868 MHz was implemented, which is made up of an ICL antenna on FR-4 substrate and a rectifier fabricated in the 0.13- $\mu \text{m}$ CMOS technology. Measurements in the anechoic chamber show an overall efficiency performance of 34% with an RF input power as low as −21.5 dBm while considering 2.4 V and 1 $\mu \text{A}$ as load specifications. [ABSTRACT FROM AUTHOR]

The analysis and modeling of monolithic stacked transformers fabricated in a high-speed silicon bipolar technology is addressed. On-wafer experimental measurements are employed to investigate the effect of layout scaling on transformer performance parameters (i.e., self-resonance frequency, magnetic coupling coefficient, and insertion loss). Based on this analysis, a wideband lumped model is developed, whose parameters are related to layout and technological data through closed-form expressions. Model accuracy is demonstrated by comparing simulated and measured S-parameters, coil inductance, magnetic coupling coefficient, and maximum available gain of several transformers with scaled layout geometry. The self-resonance frequency is also employed as a figure-of-merit to demonstrate model accuracy at very high frequency. [ABSTRACT FROM AUTHOR]

This paper presents a 77-GHz automotive radar receiver in a 28-nm fully depleted silicon-on-insulator CMOS technology. It exploits a mixer-first direct-conversion architecture to trade-off noise and linearity performance. The receiver is composed of a 77-GHz downconverter, a variable-gain amplifier, and a switched-capacitor low-pass filter. It adopts an effective and robust approach for leakage suppression due to the TX to RX crosstalk, which overcomes both gain and linearity limitations. The receiver draws an overall quiescent current as low as 27 mA from a 1-V supply voltage and provides an overall gain up to 75 dB with a noise figure of 8.2 dB. Despite the low supply voltage, an excellent blocker immunity of −9.5 dBm is achieved along with an output 1-dB compression point as high as −1.5 dBV. [ABSTRACT FROM AUTHOR]

This article presents a $W$ -band power amplifier (PA) for automotive radar applications. It was designed in a 28-nm fully depleted silicon-on-insulator CMOS technology with a transition frequency of around 270 GHz and a standard back-end-of-line. The circuit adopts a pseudo-differential topology with coupling transformers, which allow both compact matching networks and layout-optimized interstage interconnections. The power stage exploits a transformer-based folded-cascode structure that is very suitable for low-voltage mm-wave power applications. The PA is able to deliver a saturated output power as high as 13.5 dBm at 77 GHz with a power-added efficiency of 14.5%, while using a power supply as low as 1 V. The linear power gain is 26.5 dB and the current consumption is 150 mA. The PA occupies a core die size of $700\,\,\mu \text{m}\,\,\times 200\,\,\mu \text{m}$. [ABSTRACT FROM AUTHOR]

In this paper, the effect of a metal patterned ground shield (PGS) on the performance of monolithic inductors is investigated. To this aim, three spiral inductors integrated in a 28‐nm fully depleted (FD) silicon‐on‐insulator (SOI) CMOS technology are analyzed by means of a 3‐D FEM‐based commercial software. The inductors have been designed at different operating frequencies in the RF and mm‐wave ranges to better explore the effect of the PGS. Extensive analysis revealed that the shield is able to improve the quality factor (Q‐factor) only of the inductor operated at the lowest frequency (ie, K‐band). On the contrary, it has a detrimental effect on the Q‐factor of the inductors working at higher frequencies. This is mainly due to induced losses in the PGS itself, which are so high to frustrate the substrate loss reduction. This result gives a different perspective to the adoption of the PGS for CMOS integrated inductors, which is largely recommended to improve inductor performance in the current state of the art. [ABSTRACT FROM AUTHOR]

Abstract This work presents a review of integrated transformers for galvanic isolation with particular focus on their modelling in power transfer systems. A comparison between transformer-coupled oscillator topologies is carried out, highlighting the main differences in the realization of the isolation transformers. Lumped geometrically scalable modelling of the most adopted isolation transformer topologies are presented and compared. Transformer models have been validated by means of electromagnetic simulations in a wide range of geometrical parameters, achieving absolute errors lower than 12% for inductance, Q -factor peak, self-resonance frequency, and magnetic coupling factor. Highlights • A review of integrated transformers for galvanically isolated dc-dc converters. • Scalable lumped models of three different transformer configurations are compared. • The results can be exploited within an iterative co-design procedure. [ABSTRACT FROM AUTHOR]