Sungdo Kim

Frequency-dependent series resistance of monolithic spiral inductors

We present the analysis of the frequency dependent inductor series resistance (R/sub s/). The high-frequency effects on series resistance have been confirmed with measured and simulated data of inductors having different geometric and process parameters in order to predict and optimize the high-performance inductors used in radio frequency (RF) integrated circuits (ICs). The results show that the magnetic field effect seems to be a dominant factor in determining the R/sub s/ in the high-frequency region.

A Centimeter Resolution, 10 m Range CMOS Impulse Radio Radar for Human Motion Monitoring

A single-chip impulse radio radar transceiver that enables high-resolution reception with enhanced signal to noise ratio (SNR) is proposed. The radar transceiver, consisting of a spectrum adjustable transmitter and a 100-ps resolution 4-channel sampling receiver, successfully demonstrates in/outdoor human walk tracing, stride-rate, and respiration measurements. The 4-channel sampling receiver, which is robust against pulse distortion, utilizes track and hold samplers and integrators while sharing a single low noise amplifier. By adopting embedded control logic, the sampling receiver achieves control flexibility as well as improved performance. A repetitive reception mode can proportionally increase the SNR of the receive pulse at the cost of a longer pulse acquisition time. DC offset and low-frequency coherent noise problems caused by on-board control clock signals are resolved with the radar architecture. The single chip radar transceiver is fabricated in a 130-nm CMOS technology occupying a chip area of 3.27 mm 2. The measured results show that echo pulses are recovered with a centimeter range resolution while consuming 80 mA from a supply voltage of 1.2 V.

A high-resolution short-range CMOS impulse radar for human walk tracking

A single-chip impulse radar transceiver is presented. A high-resolution, enhanced SNR and controllability are achieved with a proposed architecture. By controlling timing between the transmit (TX) pulse and sampling clock of the receiver, echo pulses from targets are received and recovered. The TX pulse can adjust its spectrum occupancy by changing impulse shape. The 4-channel sampling receiver consists of a low noise amplifier, track and hold samplers, integrators, and a cascaded triple delay locked loop. The embedded control logic allows the radar to enhance the SNR of the received pulse using an averaging technique, and to operate at multiple reception modes. The real-time radar system measurements show that echo pulses are recovered with ≥100-psec range resolution while consuming 80 mW from 1.2-V of Vdd. An indoor human walking trace is successfully recorded. The transceiver is fabricated in a 130-nm CMOS technology occupying chip area of 3.4 mm2.

A 159.2mW SoC implementation of T-DMB receiver including stacked memories

This paper describes a system on chip (SoC) implementation of terrestrial digital multimedia broadcasting (T-DMB) receiver which integrates RF tuner, analog to digital converter (ADC), baseband processor, and multimedia processor in single silicon wafer. The pseudo-SRAM (PSRAM) and SDRAM are doubly stacked with method of silicon in package (SIP). A low-IF RF tuner and a 10 bits pipelined ADC is used in this work as IP cores. Baseband processor contains Eureka-147 digital audio broadcasting (DAB) modem, MPEG1-Layer2 decoder, and outer decoder for T-DMB. Multimedia processor is consists of 32 bit embedded micro processor, 24 bit fixed-point DSP, and H.264/AVC hardware core. The T-DMB SoC was fabricated by using 0.13 um 1 poly 8 metal (1P8M) CMOS process and it gives successful performance of 159.2 mW total power dissipation including PSRAM and SDRAM at supply voltages of 1.2 V, 2.5 V for core and I/O respectively.

A merged structure of LNA & sub-harmonic mixer for multi-band DCR applications

A merged structure of variable gain LNA and sub-harmonic mixer is designed for multi-band direct conversion receiver (DCR) applications with a 0.18 /spl mu/m CMOS process. The circuit uses inductive peaking loads to increase the 3dB-bandwidth and achieves 22.7/spl sim/32dB conversion gain, 2.8/spl sim/4.1dB DSB NF, -10.5/spl sim/4.1dBm IIP3 and 5/spl sim/17.3 dBm IIP2 from a 800 MHz to 2.4 GHz input range. The variable gain range is 11.5 dB at 2.1 GHz and typical LO to RF isolation is less than -50 dBm, and DC offset voltage is less than 10 mV. The overall power consumption is 17 mW with a 1.8 V supply voltage and the chip size is 2.3 mm/spl times/1.2 mm.

A high voltage GaN impulse generator for human detection UWB radar sensor

A radar sensor that can detect humans beyond wall is required for fire-fighting rescue robots. In this paper, we propose a high voltage impulse generator for through the wall UWB impulse radar sensors for rescue robot application. An impulse signal of 4.2-GHz is generated by the triggered Colpitts oscillator utilizing 0.25-μm GaN/SiC HEMT power device. The simulation results show that the pick-to-pick voltage of 30-V and pulse width of about 2.2-ns are obtained while consuming 22-mA from a supply voltage of 28-V. The layout size of chip is 1-mm × 1-mm.

A CMOS impulse radar DSP system for human detection

The real-time radar system is implemented using a prototype CMOS impulse radar and a DSP (Digital Signal Processor) chip for human detection. Human motions such as walk, breathing are successfully measured. The received signals of the prototype radar at high resolution (1.5 cm) with sufficient SNR are utilized. A commercial DSP chip is used to process received data. The radar signal processing for detecting a walking man and human respiration is proposed. The pulse integration as a part of radar signal processing is used for SNR improvement, also MTI (Moving Target Indicator) processing including maximum detector, comparator and direct coupling rejection is used for increasing detection probability about human target. The experiments on a walking man and human respiration are performed, and measurement results are discussed.

V-shaped defects in InxGa1−xAs/In0.52Al0.48As/InP pseudomorphic high electron mobility transistor structure

Abstract In x Ga 1− x As/In 0.52 Al 0.48 As pseudomorphic high electron mobility transistor (P-HEMT) structures have been grown on semi-insulating InP substrates at two different growth temperatures of 520°C and 540°C by molecular beam epitaxy. The mobility of 9100 cm 2 V −1 s with 2 dimensional electron gas (2DEG) carrier concentration of 5×10 12 cm −2 and the photoluminescence (PL) peak at the energy of 0.87 eV have been achieved only in the sample grown at 520°C. The cross-sectional transmission electron microscopy (XTEM) investigation revealed the defects including slip with angle of 60 and 120° to surface for the sample grown at 540°C. Most of defects are formed with the shape of V and X and this resulted in upheaval of some internal areas. In this study the defects formation mechanism in the In 0.52 Al 0.48 As epilayers grown on InP substrate was explained by the difference in thermal expansion coefficients between In 0.52 Al 0.48 As epilayers and InP substrates. Also we proposed that the slip-like defects have been formed during cooling procedure and that slip-like defects in epilayer grown on the substrate temperature of 540°C only can be formed because it was higher than the optimum temperature for defect-free epilayers.