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Ta-Shun Chu - IEEE Xplore Author Profile

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This article presents a frequency interleaved technique (FIT) that can be applied to add resonant peaks in the response of distributed amplifier (DA) for loss compensation and then a frequency-interleaved distributed amplifier (FIDA) that can achieve a high-gain and wide-bandwidth frequency response by summing multiple overlapping distinct-band frequency responses through a distributed configurati...Show More
This article describes a 10.7b 300MS/s two-step digital-slope analog-to-digital converter using an on-chip digital-offset correction. The proposed two-step digital-slope ADC is implemented using a passive track-and-hold followed by the input-polarity comparison and the two-step digital-slope conversion. The polarity of the input signal must be determined to control the level-shifting process and s...Show More
In this article, a scalable hybrid phased-array system is presented through synchronization, analog complex weighting, and digital beamforming of numerous fully integrated Ka-band four-receiver (RX)/four-transmitter (TX) phased-array transceiver integrated circuits (ICs). A 1.09-GHz clock synchronizes the local oscillator (LO) and a 50-MHz clock synchronizes analog-to-digital (A/D)/digital-to-anal...Show More
This paper describes the design and implementation of an X-band scalable 4×4 element-level digital phased array module. The module consists of sixteen active antenna elements. Each of these elements includes one custom CMOS RF SoC and one custom GaAs switch frontend IC. The RF SoC is implemented using a 65-nm CMOS process. The T/R Switch frontend IC is implemented in a 0.15-μm GaAs pHEMT process. ...Show More
A mixer-first single-RF-port duplexing RF frontend is proposed and implemented for frequency-modulated continuous-wave (FMCW) radar applications in this paper. The RF frontend is a bidirectional simultaneous frequency up-and-down converter. Equations of basic parameters of the frontend are derived to provide design criteria. The proposed radar architecture has been evaluated with an S-band (3.3-3....Show More
A large 9-10 GHz tile-based scalable phased-array system (over 128 elements) is built by flip-chip bonding of elementary antenna-in-package (AiP) modules on a large interposer PCB. Each module has a top radiating surface and a bottom BGA bonding surface. Due to the strict spacing requirement of a phased-array system, rework of any failed modules from the interposer PCB is prone to create more dama...Show More
In this paper, a highly integrated frequency-modulated continuous-wave (FMCW) radar system with a single-antenna interface for range sensing is proposed. In this paper, a circulator structure was developed and used in the radar system with the single-antenna interface. This structure capitalizes on frequency orthogonality to separate transmitted and received signals; thus, the isolation can be imp...Show More
This paper presents a rotatable cyclic Vernier digital-to-time converter (DTC) with 1.8 ps timing resolution on an 80 ns time scale. The proposed DTC features high timing resolution, and can be utilized in beam-steering arrays, which is infeasible for ordinary Vernier DTCs. The proposed DTC was implemented within a passive time-equivalent direct-sampling ultra-wideband impulse-radio radar system a...Show More
Frequency-modulated continuous-wave (FMCW) radars can provide high resolution and superior sensitivity for wireless sensing [1-3]. Radar signals, whose frequency increases or decreases linearly with time, are transmitted via an antenna, reflected from an object, and then received through an antenna after a time delay. Therefore, the frequency difference between the transmitted and received signals...Show More
This paper presents a fully-integrated Ka-band 4RX/4TX phased-array transceiver IC. The four transceiver channels are synchronized by an I/Q standing wave oscillator (SWO). Their signal phases are shifted by hybrid analog IF and LO phase interpolators, and can be controlled digitally and independently. The SWO further composes an on-chip PLL, and is locked to a 1.09 GHz off-chip global reference t...Show More
This paper presents a radar system for extracting human respiratory features. The proposed radar chip comprises three major components: a digital-to-time converter (DTC), a transmitter, and a receiver. The all-digital standard cell-based DTC achieves a timing resolution of 10 ps on a 100-ns time scale, supporting a range-gated sensing process. The transmitter is composed of a digital pulse generat...Show More
This paper presents an ultra-wideband (UWB) impulse-radio radar signal processing platform used to analyze human respiratory features. Conventional radar systems used in human detection only analyze human respiration rates or the response of a target. However, additional respiratory signal information is available that has not been explored using radar detection. The authors previously proposed a ...Show More
For a pulsed Radar SoC, the programmable phase shifter is a critical timing control unit as it dictates the “time-of-arrival”, i.e., the interval between the timing a pulse signal is launched and the timing an echo pulse is sampled. A pulsed Radar SoC often sweeps this timing parameter (from a smaller value to a larger value) to set the distance of detection of an object in a scanning fashion from...Show More
A 312GHz antenna array receiver is presented in this paper. The receiver is a double-conversion superheterodyne architecture. The first down-conversion is accomplished by a self-oscillating 3X subharmonic mixer frontend, and the second down-conversion is performed by a Gilbert-cell mixer and an LO. The receiver is co-designed and integrated with a 4-element loop antenna array. By mixing an RF inpu...Show More
This paper presents a wireless sensor system for monitoring human respiratory activities. The sensor is composed of a fully-integrated CMOS impulse radar chip and a DSP platform that is used for human respiratory feature extraction. The proposed and implemented radar chip was fabricated using in the TSMC 65nm CMOS technology. It can achieve the 1.5mm scanning resolution over the 15m scanning range...Show More
This paper presents a direct-sampling pulsed radar with a high-resolution digital-to-time converter (DTC) for estimating the time of flight (TOF), which is to identify the distance between a target and radar. The implemented direct-sampling radar can reconstruct the scanning waveforms in digital domain. The link budget of the radar transceivers is analyzed for the overall scanning range. The scann...Show More
In this letter, a wide tuning range W-band phase-locked loop (PLL) in 90 nm CMOS is presented. A novel frequency tripling topology with a single cross-coupled pair and a dual tank is proposed for the voltage-controlled oscillator (VCO) to achieve wide tuning characteristics under low power consumption. The locking range of the PLL at the fundamental tone is 25.4-29.7 GHz, and an excellent tuning r...Show More
A K-band ultra-wideband (UWB) pulse-compression (PC) automotive radar transmitter in 90-nm CMOS is presented, which is composed of the fully integrated pulse generator, mixer, driver amplifier, phase-locked loop, and timing circuitry. The PC technique with coding gain can effectively enhance the detection resolution and also improve the signal-to-noise ratio (SNR). We propose a PC transmitter allo...Show More
This paper presents a 1-6-GHz scalable microradio receiver unit that can be used in radiation pattern measurement. With no mechanical movement or manual adjustment, the measuring environment with the scalable microradio receiver substantially enhances the degrees of freedom and reduces the cost and time in radiation pattern measurement. Implemented in a 90-nm CMOS technology supporting a 1-6-GHz f...Show More
Impulse radar is a promising method for achieving high-range resolution and multi-path immunity for ranging and localization applications [1], [2]. Impulse radar sends signals with short duration and spreads signal power over a large bandwidth. Favorable features of impulse radar are minor interference with other wireless systems as well as high immunity to nearby radio signals. Thus, impulse rada...Show More
This paper presents a ultra-wideband (UWB) impulse radio timed-array radar utilizing time-shifted direct-sampling architecture. Time shift between the sampling time of the transmitter and the receiver determines the time of arrival (TOA), and a four-element timed antenna array enables beamforming. The different time shifts among the channels at the receiver determine the object's direction of arri...Show More
This paper presents a 2-D direct-coupled standing-wave oscillator (SWO) array implemented in a 90nm CMOS technology with 61.5GHz oscillation frequency. The SWO array can provide synchronous signals with identical frequencies, amplitudes, and phases at multiple locations over a chip. The reported SWO array is a reticular structure in a plane, and therefore it can be extended in two dimensions perio...Show More
A direct-coupled technique for standing wave oscillator (SWO) arrays is presented in this paper. The oscillation currents of a unit cell in the SWO array directly inject to adjacent cells through the resonator. Two 2-D SWO arrays based on the technique are reported. The first SWO array can provide synchronous signals with identical frequencies, amplitudes, and phases at multiple locations over a c...Show More
This paper presents a human respiratory feature extraction algorithm and its implementation on an ultra-wideband (UWB) impulse-radio radar signal processing platform. The conventional human detection algorithms only extract the respiration rate by the radar system. However, there is more information that is never explored in the radar-detected respiratory signals. Thus, this study proposes a modif...Show More
A broadband true-time-delay-based multi-beam array architecture is presented in this paper that is applicable to 1-D and 2-D linear antenna arrays. A 1-D millimeter-wave multi-beam array receiver and a 2-D ultra-wide band multi-beam array receiver have been implemented in 0.13- μm SiGe and a 0.13- μm CMOS technology, respectively. The 1-D millimeter-wave multi-beam array receiver with six antennas...Show More