The market for driver assistance systems based on millimeter-wave radar sensor technology is gaining momentum. In the near future, the full range of newly introduced car models will be equipped with radar based systems which leads to high volume production with low cost potential. This paper provides background and an overview of the state of the art of millimeter-wave technology for automotive radar applications, including two actual silicon based fully integrated radar chips. Several advanced packaging concepts and antenna systems are presented and discussed in detail. Finally measurement results of the fully integrated radar front ends are shown.

Millimeter-Wave Technology for Automotive Radar Sensors in the 77 GHz Frequency Band

This tutorial presents an overview of the technological advances in millimeter-wave (mm-wave) circuit components, antennas, and propagation that will soon allow 60-GHz transceivers to provide multigigabit per second (multi-Gb/s) wireless communication data transfers in the consumer marketplace. Our goal is to help engineers understand the convergence of communications, circuits, and antennas, as the emerging world of subterahertz and terahertz wireless communications will require understanding at the intersections of these areas. This paper covers trends and recent accomplishments in a wide range of circuits and systems topics that must be understood to create massively broadband wireless communication systems of the future. In this paper, we present some evolving applications of massively broadband wireless communications, and use tables and graphs to show research progress from the literature on various radio system components, including on-chip and in-package antennas, radio-frequency (RF) power amplifiers (PAs), low-noise amplifiers (LNAs), voltage-controlled oscillators (VCOs), mixers, and analog-to-digital converters (ADCs). We focus primarily on silicon-based technologies, as these provide the best means of implementing very low-cost, highly integrated 60-GHz mm-wave circuits. In addition, the paper illuminates characterization techniques that are required to competently design and fabricate mm-wave devices in silicon, and illustrates effects of the 60-GHz RF propagation channel for both in-building and outdoor use. The paper concludes with an overview of the standardization and commercialization efforts for 60-GHz multi-Gb/s devices, and presents a novel way to compare the data rate versus power efficiency for future broadband devices.

http://faculty.poly.edu/~tsr/wp-content/uploads/publications/abstract17.pdf

State of the Art in 60-GHz Integrated Circuits and Systems for Wireless Communications

Antenna-on-chip (AoC) and antenna-in-package (AiP) solutions are studied for highly integrated millimeter-wave (mmWave) devices in wireless communications. First, the background, regulations, standard, and applications of 60-GHz wireless communications are briefly introduced. Then, highly integrated 60-GHz radios are overviewed as a basis for the link budget analysis to derive the antenna gain requirement. Next, in order to have deep physical insight into the AoC solution, the silicon substrate's high permittivity and low resistivity effects on the AoC efficiency are examined. It is shown that the AoC solution has low efficiency, less than 12% due to large ohmic losses and surface waves, which requires the development of techniques to improve the AoC efficiency. After that, the AiP solution and associated challenges such as how to realize low-loss interconnection between the chip and antenna are addressed. It is shown that wire-bonding interconnects, although inferior to the flip-chip, are still feasible in the 60-GHz band if proper compensation schemes are utilized. An example of the AiP solution in a low-temperature cofired ceramic (LTCC) process is presented in the 60-GHz band showing an efficiency better than 90%. A major concern with both AoC and AiP solutions is electromagnetic interference (EMI), which is also discussed. Finally, the systems level pros and cons of both AoC and AiP solutions are highlighted from the electrical and economic perspectives for system designers.

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Antenna-on-Chip and Antenna-in-Package Solutions to Highly Integrated Millimeter-Wave Devices for Wireless Communications

A fully-integrated FMCW radar system for automotive applications operating at 77 GHz has been proposed. Utilizing a fractional- synthesizer as the FMCW generator, the transmitter linearly modulates the carrier frequency across a range of 700 MHz. The receiver together with an external baseband processor detects the distance and relative speed by conducting an FFT-based algorithm. Millimeter-wave PA and LNA are incorporated on chip, providing sufficient gain, bandwidth, and sensitivity. Fabricated in 65-nm CMOS technology, this prototype provides a maximum detectable distance of 106 meters for a mid-size car while consuming 243 mW from a 1.2-V supply.

A Fully-Integrated 77-GHz FMCW Radar Transceiver in 65-nm CMOS Technology

This paper presents a low power 60 GHz transceiver that includes RF, LO, PLL and BB signal paths integrated into a single chip. The transceiver has been fabricated in a standard 90 nm CMOS process and includes specially designed ESD protection on all mm-wave pads. With a 1.2 V supply the chip consumes 170 mW while transmitting 10 dBm and 138 mW while receiving. Data transmission up to 5 Gb/s on each of I and Q channels has been measured, as has data reception over a 1 m wireless link at 4 Gb/s QPSK with less than 10-11 BER.

A 90 nm CMOS Low-Power 60 GHz Transceiver With Integrated Baseband Circuitry

The first 77 GHz frequency modulated continuous wave (FMCW) radar transceiver IC with an accurate FMCW chirp signal generator using a 90 nm CMOS process is presented. To realize accurate FMCW radar system in CMOS, a PLL synthesizer based FMCW generator with chirp smoothing technique that is able to output linear FMCW frequency chirp using a nonlinear reference chirp signal supplied from a low spec/cost digital-oriented frequency reference is applied. The fabricated IC consists of an LNA, a down-conversion mixer with an output buffer, a driver amplifier, a power amplifier with power combiner, an LO distributer and an FMCW synthesizer. The measured FMCW signal from the proposed FMCW generator achieves 93 kHz frequency error (nonlinearity) at the 77 GHz chip signal. Radar performance of the IC has less than 1% ranging error from 1 m to 8 m distance from the measurement in a laboratory. These results show the transceiver achieves a fundamental function for radar applications with 520 mW power consumptions.

A 77 GHz 90 nm CMOS Transceiver for FMCW Radar Applications

A 60-GHz receiver (RX) front-end chip fabricated in 90 nm CMOS process is presented. The RX chip consists of an LNA, a downconversion mixer, and a phase-locked loop synthesizer. The RX chip is capable of generating LO signal from phase-locked synthesizer. The components of the RX chip employ fully differential architecture to avoid influences of parasitic components and operate with low LO signal amplitude. Measured power gain and NF of 22 dB and 8.4 dB were obtained at 61.5 GHz, respectively, and the RX chip receives a radio signal with an on-chip dipole antenna. These results indicate the possibility of realization of a CMOS single-chip 60-GHz transceiver.

A 60-GHz CMOS Receiver Front-End With Frequency Synthesizer

This paper presents a fully integrated CMOS 60-GHz transceiver chipset for short-range and high-speed wireless communication. The target application of the short-range communication is less than 5-cm communication distance and more than 2-Gb/s throughput for file transfer. In order to achieve file transfer, physical (PHY) layers with error packet correction and media access control (MAC) layer with frame-exchanging function are implemented. The MAC is designed to have a high-efficiency feature due to short interval DATA/Acknowledgement (ACK) frame exchange. It is realized by fast transmitter (TX)/receiver (RX) switching. A bonding wire-based in-package antenna is adopted using a standard BGA package without any off-chip 60-GHz components. The proposed chipset is composed of two chips, an RF chip with in-package antenna, and a baseband chip including PHY and MAC layer. The fabricated chipset achieves 2.62-Gb/s PHY data rate, 2.07-Gb/s MAC throughput, and energy consumption of 651 pJ/bit in 3-cm distance.

A 2-Gb/s Throughput CMOS Transceiver Chipset With In-Package Antenna for 60-GHz Short-Range Wireless Communication

A 60-GHz phase-locked loop (PLL) with inductor-less prescaler is fabricated in a 90-nm CMOS process. The inductor-less prescaler has a smaller chip area than previously reported ones. The PLL operates from 61 to 63 GHz and consumes 78 mW from a 1.2 V supply. The phase noise at 100 kHz and 1 MHz offset from carrier are -72 and -80 dBc/Hz, respectively. The prescaler occupies 80 x 40 mum2. The active area of the PLL is 0.6 x 0.6 mm2.

A 60-GHz phase-locked loop with inductor-less prescaler in 90-nm CMOS

The fisrt 77 GHz frequency modulated continuos wave (FMCW) radar transceiver IC with an accurate FMCW signal generator using a 90 nm CMOS process is presented. To realize accurate FMCW radar system in CMOS, a PLL synthesizer that is able to output linear FMCW frequency is applied. Measured radar performances, output spectrum and distance of a target, show the transceiver achieves a fundamental function for radar applications.

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Hiroaki Hoshino

Papers

A 77 GHz 90 nm CMOS Transceiver for FMCW Radar Applications

A 60-GHz CMOS Receiver Front-End With Frequency Synthesizer

A 2-Gb/s Throughput CMOS Transceiver Chipset With In-Package Antenna for 60-GHz Short-Range Wireless Communication

A 60-GHz phase-locked loop with inductor-less prescaler in 90-nm CMOS

A 77 GHz 90 nm CMOS transceiver for FMCW radar applications