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

An integrated circuit and method of fabricating the integrated circuit is disclosed. The integrated circuit includes vertical bipolar transistors (30, 50, 60), each having a buried collector region (26′). A carbon-bearing diffusion barrier (28 c) is disposed over the buried collector region (26′), to inhibit the diffusion of dopant from the buried collector region (26′) into the overlying epitaxial layer (28). The diffusion barrier (28 c) may be formed by incorporating a carbon source into the epitaxial formation of the overlying layer (28), or by ion implantation. In the case of ion implantation of carbon or SiGeC, masks (52, 62) may be used to define the locations of the buried collector regions (26′) that are to receive the carbon; for example, portions underlying eventual collector contacts (33, 44 c) may be masked from the carbon implant so that dopant from the buried collector region (26′) can diffuse upward to meet the contact (33). MOS transistors (70, 80) including the diffusion barrier (28) are also disclosed.

Control of dopant diffusion from buried layers in bipolar integrated circuits

A SiGe bipolar transistor containing substantially no dislocation defects present between the emitter and collector region and a method of forming the same are provided. The SiGe bipolar transistor includes a collector region of a first conductivity type; a SiGe base region formed on a portion of said collector region; and an emitter region of said first conductivity type formed over a portion of said base region, wherein said collector region and said base region include carbon continuously therein. The SiGe base region is further doped with boron.

Incorporation of carbon in silicon/silicon germanium epitaxial layer to enhance yield for Si-Ge bipolar technology

This paper presents a 15-dBm power amplifier for 77-GHz automotive radar applications, which is fabricated in a 0.13-μm SiGe:C BiCMOS process featuring bipolar transistors with fT /fmax 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.

A 15-dBm SiGe BiCMOS PA for 77-GHz Automotive Radar

This paper presents fuzzy ${c}$ -means-based yield estimation (FUZYE), a methodology that reduces the time impact caused by Monte Carlo (MC) simulations in the context of analog integrated circuits (ICs) yield estimation, enabling it for yield optimization with population-based algorithms, e.g., the genetic algorithm (GA). MC analysis is the most general and reliable technique for yield estimation, yet the considerable amount of time it requires has discouraged its adoption in population-based optimization tools. The proposed methodology reduces the total number of MC simulations that are required, since, at each GA generation, the population is clustered using a fuzzy ${c}$ -means (FCMs) technique, and, only the representative individual (RI) from each cluster is subject to MC simulations. This paper shows that the yield for the rest of the population can be estimated based on the membership degree of FCM and RIs yield values alone. This new method was applied on two real circuit-sizing optimization problems and the obtained results were compared to the exhaustive approach, where all individuals of the population are subject to MC analysis. The FCM approach presents a reduction of 89% in the total number of MC simulations, when compared to the exhaustive MC analysis over the full population. Moreover, a ${k}$ -means-based clustering algorithm was also tested and compared with the proposed FUZYE, with the latest showing an improvement up to 13% in yield estimation accuracy.

FUZYE: A Fuzzy ${c}$ -Means Analog IC Yield Optimization Using Evolutionary-Based Algorithms

A new relaxation-time-approximation-based nonquasi-static (NQS) MOSFET model, consistent between transient and small-signal simulations, has been developed for surface-potential-based MOSFET compact models. The new model is valid for all regions of operation and is compatible with, and at low frequencies recovers, the quasi-static description of the MOSFET. The model is implemented in two widely used circuit simulators and is tested for speed and convergence. It is verified by comparison with technology computer-aided design simulations and experimental data and by application of a recently developed benchmark test for NQS MOSFET models.

Accurate RTA-Based Nonquasi-Static MOSFET Model for RF and Mixed-Signal Simulations

Corner (best- and worst-case) models have been a mainstay of integrated circuit design for decades. Obviously they can be effective, especially for digital CMOS design. However, there are significant inaccuracies that arise when digital CMOS corner models are used for analog circuits, or any types of circuits or measures of circuit performance they were not targeted for. This paper details what corner models can and cannot do, and shows their inadequacies for analog CMOS circuits.

Corner models: Inaccurate at best, and it only gets worst …

A method of manufacturing a heterojunction BiCMOS IC (100) includes forming a gate electrode (121, 131), forming a protective layer (901, 902) over the gate electrode, forming a semiconductor layer (1101) over the protective layer, depositing an electrically insulative layer (1102, 1103) over the semiconductor layer, using a mask layer (1104) to define a doped region (225) in the semiconductor layer and to define a hole (1201) in the electrically insulative layer, forming an electrically conductive layer (1301) over the electrically insulative layer, using another mask layer (1302) to define an emitter region (240) in the electrically conductive layer and to define an intrinsic base region (231) and a portion of an extrinsic base region (1502) to define another portion of the extrinsic base region in the electrically conductive layer.

Method of manufacturing a heterojunction BiCMOS integrated circuit

Recent advancements in SiGe device development enable the realization of 77GHz automotive long range radar systems using relatively low-cost silicon technology. This paper will discuss technology requirements for the radar design and present examples of receiver and transmitter circuit implementations.

SiGe 77GHz Automotive Radar Technology

A millimeter-wave hyperabrupt-junction varactor (HAVAR) enabling 77GHz VCO/TX with 13–15GHz tuning range and better than −70dBc/Hz phase noise at 100kHz offset has been integrated in SiGe:C BiCMOS for automotive radar products. The HAVAR predominantly uses existing processes for low-cost integration and minimal process complexity. Optimization of TR-Q thru HAVAR width allows TR up to 2.7 and Q min up to 10.

Ik-Sung Lim

Papers

Accurate RTA-Based Nonquasi-Static MOSFET Model for RF and Mixed-Signal Simulations

Corner models: Inaccurate at best, and it only gets worst …

Method of manufacturing a heterojunction BiCMOS integrated circuit

SiGe 77GHz Automotive Radar Technology

Hyperabrupt-junction varactor for mmWave SiGe:C BiCMOS, enabling 77GHz VCO/TX with 13-15GHz tuning range