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Dive into the research topics where Afreen Azhari is active.

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Featured researches published by Afreen Azhari.


IEEE Access | 2015

A Radar-Based Breast Cancer Detection System Using CMOS Integrated Circuits

Hang Song; Hayato Kono; Yuji Seo; Afreen Azhari; Junichi Somei; Eiji Suematsu; Yuichi Watarai; Toshihiko Ota; Hiromasa Watanabe; Yoshinori Hiramatsu; Akihiro Toya; Xia Xiao; Takamaro Kikkawa

An ultrawideband (UWB) radar-based breast cancer detection system, which is composed of complementary metal-oxide-semiconductor integrated circuits, is presented. This system includes Gaussian monocycle pulse (GMP) generation circuits, switching (SW) matrix circuits, equivalent-time sampling circuits, and a compact UWB antenna array. During the detection process, the GMP signal with the center frequency of 6 GHz is first generated and transmitted with a repetition frequency of 100 MHz. The GMP signal is sent to a selected transmitter antenna by the SW matrix module, and the reflected signal is captured by the receiver antennas. Next, the high-speed equivalent-time sampling circuits are employed to retrieve the reflected GMP signal. A confocal algorithm is used to reconstruct the breast image. The total size for the prototype module is 45 cm×30 cm×14.5 cm in length, width, and height, respectively, which is dramatically smaller than the conventional detection systems. Using our proposed system, we demonstrate a successful detection of 1-cm cancer target in the breast phantom.


biomedical circuits and systems conference | 2014

A 17 GHz bandwidth 1.2 mW CMOS switching matrix for UWB breast cancer imaging

Afreen Azhari; Sugitani Takumi; Sogo Kenta; Takamaro Kikkawa; Xia Xiao

A new single pole eight throw (SP8T) CMOS switching matrix has been developed to replace conventional large mechanical switches, for portable ultra wideband (UWB) breast cancer imaging system. The SP8T switch has an minimum input and output matching bandwidth of 0-17 GHz with an average insertion loss of 3 to 10 dB from 2 to 17 GHz and power consumption of 1.2 mW. By utilizing two of these switching matrices, implemented on printed circuit boards, it has been possible to detect an aluminum target of 10 mm × 10mm at a depth of 20 mm, in a 16 antenna array breast cancer detection system. An 8 GHz center frequency Gaussian monocycle pulse was transmitted through the whole system.


Japanese Journal of Applied Physics | 2011

A 5.4–9.2 GHz 19.5 dB Complementary Metal–Oxide–Semiconductor Ultrawide-Band Receiver Front-End Low-Noise Amplifier

Afreen Azhari; S. Kubota; Akihiro Toya; Nobuo Sasaki; Takamaro Kikkawa

In this work, we present an ultrawide-band (UWB) complementary metal–oxide–semiconductor (CMOS) low-noise amplifier (LNA) for wireless communication in the upper UWB band, that is, from 5.4–9.2 GHz bandwidth with a wide-band 50 Ω input matching network in front of the LNA. A three-stage cascode-topology-based LNA with high-transconductance MOS transistors, was employed to improve the voltage gain up to 23 dB at 7.5 GHz, with 4.5–9.2 GHz 3 dB bandwidth. The maximum output power S21 was 19.5 dB at 7.3 GHz, with 5.4–9.2 GHz 3 dB bandwidth. The input matching circuit was designed with a reduced number of passive elements, resulting in an input reflection coefficient S11 of less than -10 dB from 4.5–9.2 GHz. The noise figure of the LNA was as low as 3.5 dB and the input-referred third-order intercept point (IIP3) was -8 dBm. The LNA has output reflection coefficient S22 of less than -10 dB from 5–7 GHz and a good reverse isolation, that is, S12 of < -45 dB in the entire UWB, due to a cascode topology. The LNA was fabricated using 180 nm CMOS technology, which consumes 56 mW power at 1.8 V power supply. In this paper, we also demonstrate a wireless communication of 7 GHz Gaussian monocycle pulse (GMP) by horn antennas and the LNA from 20 cm transmission distance.


Japanese Journal of Applied Physics | 2010

A 3.5–4.5 GHz Complementary Metal–Oxide–Semiconductor Ultrawideband Receiver Frontend Low-Noise Amplifier with On-Chip Integrated Antenna for Interchip Communication

Afreen Azhari; K. Kimoto; Nobuo Sasaki; Takamaro Kikkawa

Chip-to-chip ultrawideband (UWB) wireless interconnections are essential for reducing resistance capacitance (RC) delay in wired interconnections and three-dimensional (3D) highly integrated packaging. In this study, we demonstrated a wireless interchip signal transmission between two on-chip meander antennas on printed circuit board (PCB) for 1 to 20 mm transmission distances where the low power gain of each antenna due to a lossy Si substrate has been amplified by a low-noise amplifier (LNA). The measured result shows that the LNA produces 26 dB of improvement in antenna power gain at 4.5 GHz on a lossy Si substrate. Moreover, a Gaussian monocycle pulse with a center frequency of 2.75 GHz was also received by an on-chip antenna and amplified by the LNA. The LNA was integrated with an on-chip antenna on a Si substrate with a resistivity of 10 Ωcm using 180 nm complementary metal–oxide–semiconductor (CMOS) technology. The investigated system is required for future single chip transceiver front ends, integrated with an on-chip antenna for 3D mounting on a printed circuit (PC) board.


biomedical circuits and systems conference | 2014

CMOS equivalent time sampling of Gaussian monocycle pulse for confocal imaging

Yuji Seo; Kenta Sogo; Akihiro Toya; Takumi Sugitani; Afreen Azhari; Xia Xiao; Takamaro Kikkawa

CMOS 102.4 GS/s equivalent time sampling (ETS) circuits with a track and hold, phase-locked loop and analog to digital converter was developed for radar-based breast cancer detection. The track and hold circuits of the ETS covered the bandwidth of 2.9-13.9 GHz by use of a 1.27 nH series inductor to compensate parasitic capacitances. The pulse width and the bandwidth of the input Gaussian monocycle pulse (GMP) were 107 ps and 4.45-15.8 GHz, respectively. The received GMP waveforms by 4 × 4 antenna array were converted to 4-bit digital codes. A three dimensional confocal imaging of a 20 × 20 mm2 target in a homogeneous breast phantom was demonstrated.


International Journal of Antennas and Propagation | 2017

Microwave Imaging Using CMOS Integrated Circuits with Rotating 4 × 4 Antenna Array on a Breast Phantom

Hang Song; Afreen Azhari; Xia Xiao; Eiji Suematsu; Hiromasa Watanabe; Takamaro Kikkawa

A digital breast cancer detection system using 65 nm technology complementary metal oxide semiconductor (CMOS) integrated circuits with rotating 4 × 4 antenna array is presented. Gaussian monocycle pulses are generated by CMOS logic circuits and transmitted by a 4 × 4 matrix antenna array via two CMOS single-pole-eight-throw (SP8T) switching matrices. Radar signals are received and converted to digital signals by CMOS equivalent time sampling circuits. By rotating the 4 × 4 antenna array, the reference signal is obtained by averaging the waveforms from various positions to extract the breast phantom target response. A signal alignment algorithm is proposed to compensate the phase shift of the signals caused by the system jitter. After extracting the scattered signal from the target, a bandpass filter is applied to reduce the noise caused by imperfect subtraction between original and the reference signals. The confocal imaging algorithm for rotating antennas is utilized to reconstruct the breast image. A 1 cm3 bacon block as a cancer phantom target in a rubber substrate as a breast fat phantom can be detected with reduced artifacts.


european conference on antennas and propagation | 2012

IR-UWB-CMOS circuits for breast cancer detection

Takamaro Kikkawa; Akihiro Toya; S. Kubota; Mohiuddin Hafiz; Afreen Azhari; Nobuo Sasaki


asia-pacific microwave conference | 2014

A CMOS 65 nm DC-17 GHz single pole eight throw switch for 8 GHz radar impulse communication

Afreen Azhari; Sugitani Takumi; Sogo Kenta; Takamaro Kikkawa


international symposium on antennas and propagation | 2016

Confocal imaging by turning antennas with CMOS integrated circuits for breast cancer detection

Hang Song; Hayato Kono; Yuji Seo; Afreen Azhari; Xia Xiao; Takamaro Kikkawa


Japanese Journal of Applied Physics | 2018

Transmit/receive 3–20 GHz 1.2 mW packaged double-pole-16-throw switching matrix for radar-based target detection

Afreen Azhari; Yuki Kuwano; Xia Xiao; Takamaro Kikkawa

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Yuji Seo

Hiroshima University

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