Research Overview
Our Research Areas
Sabancı University MicroElectronics Research group (SUMER) has a very active research group working on different areas of electronics including integrated circuit design for high frequency, analog and mixed signal applications, sensor development and sensor interface design for different applications.
The research group mainly focuses on 5 major research areas, which are high frequency integrated circuit design upto 240 GHz (RFIC, mm-wave IC, 5G, Terahertz Imaging, Radiometry), mixed signal integrated circuit design (ReadOut Integrated Circuit (ROIC) design for infrared imaging systems, ADC, DAC, etc.), energy harvesting, biosensor and biosensor interface design, MicroElectroMechanical System (MEMS) design for different applications.
Many ongoing and completed projects, that are supported by leading companies of industry, The Scientific and Technological Research Council of Turkey, Turkish Ministry of Science, Industry and Technology, European Union, are conducted by the members of the research group.
The research group has access to many semiconductor foundaries, industry standard CAD tools. There is also a class 1000 clean room that can be utilized for low volume, simple device fabrication projects. For advanced fabrication requirement Sabancı University Nanotechnology Research and Application Center(SUNUM) is available for the use of the group. There are also many measurement tools,listed in the labs section, that can be utilized for different applications ranging from dc to very high frequency, from cryogenic temperarures (-196 C) to 200 C.
Phased Array Systems
High performance T/R module core chip within its sub-blocks for X-Band phased array RADAR applications is one of the research topics of our group, including wideband and ultra-low noise amplifiers, high resolution phase shifters and attenuators.
Millimeter-wave (30-300 GHz)
We are interested in mm-wave communication, RADAR, imaging and measurement techniques which can be implemented in SiGe BiCMOS technology.
5G and Beyond
We focus on high performance wireless communication circuits targeting 5G applications, especially at 28 GHz. Research includes full duplex radios, adaptive self-interference cancellers, high efficiency power amplifiers and wideband low noise amplifiers.
Mixed Signal and Readout IC
The emphasis of this group is on data converter design and on readout/signal conditioning circuits for infrared focal plane arrays based on thermal and photodetectors.
RF MEMS
The developments of RF-MEMS components provide an answer to the performance needs in millimeter-wave electronics. We focus on designing high-performance RF-MEMS components which can be easily integrated with other RF blocks.
SiGe Uncooled Infrared Detector
The primary focus in this area is to design, develop, characterize and measure the SiGe Based Multi-Quantum Well IR bolometer and detector arrays/elements, consisting of the development and manufacturing steps and processes (in collaboration with IHP Microelectronics).
Biosensors and Lab-On-a-Chip
We address the design and development of novel micro/nanosensors biosensors, complex and compact miniaturized systems for biological and biomedical applications.
Energy Harvesting
We investigate methods to efficiently collect coherent infrared radiation and convert it to DC power. Currently, our research focuses on the development and enhancement of rectenna arrays to collect Medium Wavelength Infra-Red Radiation (MWIR).
Phased Array Systems
Previous generation phased array RADAR systems fail to meet new performance features, due to including mechanical beam scanning and being less resistant to outside effects such as vibration, while new generation systems give opportunity of achieving fast beam scanning by varying the direction of multiple antenna elements electronically. Transmitter/Receiver (T/R) modules are one of the essential blocks in a phased array RADAR system, because of being dominant on major system features like operating frequency, sensitivity, output power and phase shifting, which are determined by related sub-blocks of a T/R module.
Our research group focuses on the design of fully integrated T/R core chips for X-Band phased array RADAR applications in SiGe BiCMOS technology and their sub-blocks such as LNA, PA, PS, SPDT, Attenuator or VGA. We also work on wideband transceivers, ultra-low noise amplifiers, high resolution phase shifters, wideband attenuators.
Millimeter-wave (30-300 GHz)
In the recent years, design of millimeter-wave (30-300 GHz) integrated circuits for various applications such as automotive radars, high data-rate wireless communication systems and especially active/passive imaging has become an active research area. In this context, our two joint projects with IHP GmbH –Leibniz Institut für innovative Mikroelektronik have been supporting by TUBITAK (The Scientific and Technological Research Council of Turkey) since 2015.
1) Design of fully integrated 94 GHz radiometer for passive millimeter wave imaging using SiGe BiCMOS technology
The aim of this project is design of a low NETD (Noise Equivalent Temperature difference) mm-wave radiometer which will be used in passive imaging systems. In this project, the sub blocks of a single chip 94 GHz direct detection radiometer system - such as on chip antenna, LNA, power detector, SPDT were designed, optimized, fabricated, tested and verified. The building of the radiometer system is ongoing.
2) MEMS Switch and MEMS-Variable Capacitor Integrated SiGe-BiCMOS Technology –Based, Monolithic 140 GHz Radiometry and 240 GHz Spectroscopy FrontEnd Circuits
The main goal of the THzMEMS project is the first time monolithic integration of MEMS switch and tunable capacitors into a 0.13 µm BiCMOS process for THz circuit and system applications. The target applications of the project are 140 GHz passive imaging radiometer and 240 GHz spectroscopy. The main motivation is the enhancement of the performance of switch and tunable capacitor circuit components using the BiCMOS embedded MEMS technology; thus going beyond state of the art performance parameters that can be achieved using available/conventional technologies.
5G and Beyond
International Telecommunication Union has set challenging requirements for 5G radios (ITU's draft report for IMT-2020) such as 20 Gbps downlink and 10 Gbps uplink peak data rates, 30 bps/Hz downlink and 15 bps/Hz uplink spectral efficiencies, 1 million connected devices per km2, support up to 500 km/h speeds and down to 1 ms latency. To meet these requirements, it is envisioned that technologies such as mm-waves, small cells, massive MIMO, beamforming and full duplex will be used.
Our research is on the development of SiGe based integrated circuits targeting these 5G applications. We work on subcircuits such as
- Noise reduction and linearity improvement techniques for LNAs
- Wideband LNAs (20-40 GHz)
- High efficiency PAs, class-F and class-F-1
- Digitally-controlled phase shifters and attenuators
Mixed Signal and Readout Integrated Circuits
The research conducted within the Mixed Signal and Readout IC Group falls under two categories: (1) ROIC design for Infrared Imaging Systems, (2) ADC Design for Imaging and High Speed Applications.
ROIC Design for Infrared Imaging Systems
Infrared imaging technology has caught considerable attention over the past two decades owing to its advanced imaging capabilities. Military and industrial systems have been benefiting from these capabilities for applications such as optical flash thermography, industrial process monitoring and missile warning systems.
Our research group conducts experimental and applied research on readout technologies for both photodetector and thermal type infrared detectors and sensor systems. Integrated readout is responsible for pre-amplifying, integrating and processing of the detector currents for further signal processing by a DSP chip. Applications demanding high resolution impose size requirements on the pixel introducing challenges in the readout circuits. Moreover, for systems employing photodetecors, the current trend has been towards digital pixel architectures providing in-pixel quantization of the incident charge. This enables high data rates and improved accuracy over their analog counter parts. To this end, a number of readout chips, with pixel pitch ranging from 30um to 15um, have been developed. These designs employ innovative ideas that have been patented. Some recently completed and on-going projects are listed below:
1. 32x32 Digital ROIC (DROIC) for MWIR FPAs (15um pitch)
2. 32x32 DROIC LWIR ROIC (30um pitch)
3. 320x240 Microbolometer ROIC (17um pitch)
The projects have been funded by “The Scientific and Technological Research Council of Turkey (TUBİTAK).”
ADC Design for Imaging Applications and High Speed Applications
High precision ADCs with moderate speed are needed in imaging systems employing off-pixel quantization. ROICs incorporating such ADCs either in a column-parallel fashion or as a single array-wide ADC have been developed and tested. Furthermore, the mixed signal group has recently focused on 500 MSps+ ADCs with moderate resolutions targetting a broader range of applications. Some of the completed and currently running projects are listed below:
1. 10 bit 100 KSps column SAR ADC for MWIR DROIC
2. 10 bit 5 MSps SAR ADC serving a 320x240 microbolometer array
3. A 6 bit 800 MSps time-interleaved asynchronous SAR ADC
Energy Harvesting
Current energy harvesting and detection devices operating in THz frequency regime endure inadequate efficiency with considerably high fabrication cost. The success of rectennas in the RF/microwave region has provided the inspiration for researchers to extend the rectenna concept to the THz/infrared frequency range, and even to solar/optical frequencies. As such, antenna-coupled rectifiers (rectennas) have become one of the rising candidates for exploring newer paradigms in the THz energy harvesting and detection realm. Employing THz antennas coupled with Metal-Insulator-Metal (MIM) tunneling diodes enables viable solution for efficient THz energy harvesters and detectors with significantly lower fabrication cost.
Our research group has a project which is supported by Lockheed Martın Overseas Services Corporation with the aim of developing highly efficient rectenna power collectors for Near Space Plane applications. Overall, the motivation is to harvest solar energy at higher conversion efficiency than what is achieved using current photovoltaic technology. The research mainly focuses on improving design & fabrication process development for the thin film MIM diode and its reproducibility to enhance the efficiency of the antenna-coupled diode. Our current research focuses on improving the efficiency of the radiating elements, improving the match from the radiating elements to the diodes and reducing the diode losses.
The design, fabrication and the characterization of rectenna arrays are carried out in Sabanci University Electronics Research Laboratory and Sabanci University Nanotechnology Research and Application Center (SUNUM).
Biosensors and Lab-on-a-Chip
The main activity of the group addresses the design and development of novel micro/nanosensors biosensors, complex and compact miniaturized systems for biological and biomedical applications. Device design, fabrication, packaging and characterization, as well as customized electronic instrumentation development, are approached from the initial conception to the final biosensor in order to generate knowledge, micro-nano devices and complete systems with high added value.
The group mainly works on electrochemical biosensors, their readout electronics and integration of biosensors with the readout electronics. Different strategies and architectures for the monolithic and/or hybrid integration of biological sensors with fluidic elements are also developed. Silicon and Glass technologies are being applied together with microfabrication processes such as micromolding, soft lithography, micromilling as well as a variety of materials including polydimethylsiloxane (PDMS), SU8, hybrid xerogels, polymethylmethacrylate (PMMA), polycarbonate (PC) and wax.
A prototype LoC is developed based on electrochemical biosensor arrays for the readout of Cancer and Cardiovascular Disease Markers for biomedical application. The developed medical prototype is comprised of a capacitive bio-detection chip, microfluidic, sensitive capacitive readout electronics and data analysis software which interpolates quantity of biomarkers in each test serum sample. Capacitive bio-detection chip is based on interdigitated circular lines or electrodes, which is pre-activated with single (for detecting one biomarker) or multiple antibody types (for detecting multiple disease biomarkers). Working principle of capacitive biosensor is based on the interaction of antibody and antigens on capacitive chip that causes change of capacitance which is reflected on the readout display by sensor electronics. The developed lab-on-chip device prototype combines innovative label-free features for point-of-care application, which is portable, hand-held, fast and low cost healthcare platform that can be used to diagnose CVD and cancer through detecting single/multi biomarkers representing single/multi diseases. This device can be used without having to rely on expensive and time-consuming laboratory tests. The prototype device is capable of on-site diagnosis and the result is reported in less than 30 minutes.
SiGe Uncooled Infrared Detector
In the recent years, the efforts are made for technical evolution for microbolometer in four different domains: IR optics, at the pixel level, ROIC integration, and packaging level. In general, main motivations are to upgrade the performance, to reduce cost and to increase the integration capabilities. Newer paradigms at pixel level involve pixel size reduction, new materials, and new design to enhance the detection and integration capability with ease of fabrication. SiGe Based Multi-Quantum detector technology is an emerging technology for microbolometers.
The primary focus in this area is to design, develop, characterize and measure the SiGe Based Multi-Quantum Well IR bolometer and detector arrays/elements, consisting of the development and manufacturing steps and processes (in collaboration with IHP Microelectronics), the thermoelectric modeling of the sensors, including the development of novel theoretical models, multi-physics FEM simulation modeling as well as the SPICE modeling, experimental parameter extraction techniques and the development of the necessary experimental setups.
RF MEMS
RF-MEMS components have the ability of the monolithic integration which creates fewer parasitics than heterogeneous integration techniques such as bond-wire or flip-chip. Additionally, their integration into a SiGe BiCMOS process technology creates an opportunity to use RF-MEMS blocks with high-performance HBTs. In this context, our project with IHP GmbH –Leibniz-Institut für innovative Mikroelektronik have been supporting by TUBITAK (The Scientific and Technological Research Council of Turkey) since 2015.
MEMS Switch and MEMS-Variable Capacitor Integrated SiGe-BiCMOS Technology –Based, Monolithic 140 GHz Radiometry and 240 GHz Spectroscopy FrontEnd Circuits
In this project, two RF-MEMS blocks are designed to answer the high-performance needs of millimeter-wave applications. The first component is D-band RF-MEMS switch employs to achieve high-performance on the SPDT. The second component is 240 GHz centered RF-MEMS variable capacitance which will lead to achieving high-quality, high-tunability performances of the VCO.
