Sang-Hyun Baek

A Wideband Transformer-Coupled CMOS Power Amplifier for

This paper presents a wideband transformer-coupled CMOS power amplifier (PA). On-chip transmission-line transformers are used as key components of matching networks at output, input, and interstage. The wideband on-chip transformer is harnessed without any additional inductive devices so that a wideband power characteristic can be achieved. The PA is fabricated using a 0.18-μm CMOS process. It provides a saturated output power of 21.5 dBm with the power-added efficiency (PAE) of 20.3%, and the output 1-dB gain-compressed power (P1 dB) is 20.2 dBm with the PAE of 14.8% at 9.5 GHz, respectively. The small-signal gain is 25.3 dB and the 3-dB bandwidth is 6.5 GHz (6.5-13 GHz). The die area is 1.34 mm × 0.47 mm. Among the reported X/Ku-band CMOS PAs, this amplifier achieves the highest figure of merit, and also shows suitable performances for phased-array systems.

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Circulating tumor cells (CTCs), though exceedingly rare in the blood, are nonetheless becoming increasingly important in cancer diagnostics. Despite this keen interest and the growing number of potential clinical applications, there has been limited success in developing a CTC isolation platform that simultaneously optimizes recovery rates, purity, and cell compatibility. Herein, a novel tracheal carina-inspired bifurcated (TRAB) microfilter system is reported, which uses an optimal filter gap size satisfying both 100% theoretical recovery rate and purity, as determined by biomechanical analysis and fluid-structure interaction (FSI) simulations. Biomechanical properties are also used to clearly discriminate between cancer cells and leukocytes, whereby cancer cells are selectively bound to melamine microbeads, which increase the size and stiffness of these cells. Nanoindentation experiments are conducted to measure the stiffness of leukocytes as compared to the microbead-conjugated cancer cells, with these parameters then being used in FSI analyses to optimize the filter gap size. The simulation results show that given a flow rate of 100 μL min(-1), an 8 μm filter gap optimizes the recovery rate and purity. MCF-7 breast cancer cells with solid microbeads are spiked into 3 mL of whole blood and, by using this flow rate along with the optimized microfilter dimensions, the cell mixture passes through the TRAB filter, which achieves a recovery rate of 93% and purity of 59%. Regarding cell compatibility, it is verified that the isolation procedure does not adversely affect cell viability, thus also confirming that the re-collected cancer cells can be cultured for up to 8 days. This work demonstrates a CTC isolation technology platform that optimizes high recovery rates and cell purity while also providing a framework for functional cell studies, potentially enabling even more sensitive and specific cancer diagnostics.

-Band Multifunction Chips

This paper presents a wide dynamic range (DR) CMOS root-mean-square power detector with a temperature variation compensation technique in a 28-nm CMOS process. The cascaded gain amplifiers and squaring circuits in the proposed power detector can achieve wide DR with the power level segmented detection method using a switch driver with the help of a modem. A 12-bit current digital-to-analog converter is used to calibrate dc offset in the power detector with 25- μV steps to improve the accuracy. Measured DR is more than 40 dB from 700 MHz to 4 GHz. A temperature compensation bias circuit improves the performance of the detector with maximum 0.8-dB error over the temperature range -30°C ~ 90°C. The chip area is 333 μm× 450 μm and the power consumption is from 5.8 to 11.8 mW depending on the input power using a 1.8-V power supply.

A Trachea‐Inspired Bifurcated Microfilter Capturing Viable Circulating Tumor Cells via Altered Biophysical Properties as Measured by Atomic Force Microscopy

We present a novel method for separating circulating tumor cells (CTCs) with high recovery and purity at the same time using a micro-slit filter chip and a fully automated fluidic system. Considering white blood cells (WBCs) as big as CTCs are also captured with CTCs during filtration, we amplified the size of CTCs specifically using microbeads (3 μm) coated with anti-Epithelial Cell Adhesion Molecule (anti-EpCAM) to increase the size difference between WBCs and CTCs. The average diameter of MCF-7 cells was increased from 16.5 μm to 23.1 μm. A micro filter chip having an extremely high aspect ratio (AR=3488) rectangular slit was designed to prevent clogging which induces unwanted aggregation, capturing of other small blood cells and consequently decreasing purity. A fully automated fluid control system was implemented for the better reproducibility and the minimization of handling errors. The procedures from blood loading to staining, prior to analysis, were performed automatically. With the optimized condition, separation experiments using 5ml of normal whole blood spiked with 100 MCF-7 cells have demonstrated the reduction of clogging, high recovery (91.1 %) and high purity (52.0 %) at the same time.