Ta-Shun Chu

An Integrated Ultra-Wideband Timed Array Receiver in 0.13

A fully integrated CMOS ultra-wideband 4-channel timed array receiver for high-resolution imaging application is presented. A path-sharing true time delay architecture is implemented to reduce the chip area for integrated circuits. The true time delay resolution is 15 ps and the maximum delay is 225 ps. The receiver provides 11 scan angles with almost 9 degrees of spatial resolution for an antenna spacing of 3 cm. The design bandwidth is from 1 to 15 GHz corresponding to less than 1 cm depth resolution in free space. The chip is implemented in 0.13 mum CMOS with eight metal layers, and the chip size is 3.1 mm by 3.2 mm. Measurement results for the standalone CMOS chip as well as the integrated planar antenna array and the CMOS chip are reported.

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This article covers the basic principles of true-time-delay (TTD)-based space-time array processors and ultra-wideband beamformers. General considerations regarding the need for TTD array processing, optimum array size, antenna spacing, and array patterns are discussed for communication and imaging UWB arrays. Several recent integrated circuit implementations of UWB TTD-based beamformers are presented. A few commercial applications that warrant UWB TTD-based array processing, with emphasis on imaging and sensing, are also described.

CMOS Using a Path-Sharing True Time Delay Architecture

This paper presents a wireless non-contact sensor that enables detection, localization, and monitoring of people along with their specific features such as gait and cardiopulmonary activities. These types of sensors can be embedded in the environment and networked with the existing wireless infrastructure to create an intelligent and responsive ambient where the health of children, patients, and the elderly can be monitored without intrusion. None of the common sensing modalities including visible optical, infra-red, and ultra-sound can operate under different visibility conditions, without Line-Of-Sight (LOS), under environmental noise, and measure human-specific features simultaneously. Radio Frequency (RF) sensors have been used to localize humans, and monitor their gait and vital signs [1,2]. Most of these RF sensors transmit a Continuous Wave (CW) modulated or un-modulated waveform and detect the Doppler shift caused by the movement of hearts, lungs, and other body parts — the latter referred to as micro-Doppler technique. RF sensors do not require LOS and work under extreme weather and visibility conditions.

Integrated true-time-delay-based ultra-wideband array processing

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 and seven beams covers the entire 30-40-GHz instantaneous bandwidth, and achieves 18° spatial resolution and ±54° spatial coverage with 4-mm antenna spacing. The 2-D ultra-wideband multi-beam array receiver with 2 × 2 antennas and 7 × 7 beams covers the 3-15-GHz instantaneous bandwidth, and achieves 10° spatial resolution and ±30° spatial coverage in each dimension with 3-cm antenna spacing.

A short-range UWB impulse-radio CMOS sensor for human feature detection

The phased array is a common technique where multiple spaced antennas electronically form and scan narrow electromagnetic beams to achieve spatial selectivity. These arrays are also referred to as steering arrays. On the other hand, there are many wireless communications, imaging, and sensing applications where it is highly desirable and even essential to form multiple simultaneous beams, each staring (or scanning around) a specific angle independently. These arrays are also referred to as multi-beam starring arrays.

True-Time-Delay-Based Multi-Beam Arrays

This paper presents a radio frequency (RF) CMOS chip and algorithm integrated solution of an Ultra-Wideband (UWB) Impulse-Radio (IR) radar system for human presence detection and tracking. UWB radar can complement other human detection and tracking technologies, as it works well in poor visibility conditions with high time/depth-resolution. UWB radar response provides the complex multipath scattering characteristics in each scan, as well as the high sensitive variation in dynamic observation patterns between scans to pose challenge in designing UWB radar hardware and signal processing algorithm. We develop a UWB IR CMOS human feature detection radar transceiver chip and human presence detection algorithm. Thereafter, we integrated the UWB CMOS radar chip and the algorithm through UWB sensor module, and tested the integrated system in a simple outdoor environment to validate the performance of the integrated system. We present experimental results in which the integrated UWB human detection radar system tracks human and non-human targets, and detects human presence by discerning human from moving non-human objects robustly using human feature extraction and likelihood ratio testing (LRT).

A true time-delay-based bandpass multi-beam array at mm-waves supporting instantaneously wide bandwidths

A fully integrated 4-channel UWB beam-former in 0.13μm CMOS uses a path-sharing true-time-delay architecture with 15ps resolution. The 3.1×3.2mm2 chip produces 11 different scanning angles within plusmn60deg with 10° spatial resolution for 25mm antenna spacing. The front-end achieves an NF of 2.9 to 4.8dB across 18GHz of BW with less than 5ps of group delay variation.

UWB human detection radar system: A RF CMOS chip and algorithm integrated sensor

In this paper, a UWB imaging camera with 7x7 active pixels is reported. The UWB camera consists of a CMOS chip that interfaces with 2x2 3D omni-directional UWB antennas. This receiving camera forms 7x7 simultaneous beams in two dimensions and includes an array of on-chip pulse-energy detectors for each active pixel. With 3cm of spacing between antenna elements, this 2D UWB camera achieves a 10deg spatial resolution and plusmn30deg of spatial coverage in each dimension.

A 4-Channel UWB Beam-Former in 0.13μm CMOS using a Path-Sharing True-Time-Delay Architecture

A 4-channel ultra wideband timed array transmitter chipset is reported in 0.13 mum CMOS technology that is suitable for radar and imaging applications. It consists of an all-digital timing control and impulse generation circuitry chip and a set of UWB pulse forming switches. The all-digital chip creates desired delayed versions of an input pulse sequence, which may be coded and/or pulse position modulated, for all 4 channels. It also converts the input pulse sequence to an impulse sequence. The all-digital chip can be directly connected to an antenna array to generate non-carrier based (impulse) waveforms. It can also control the timing of UWB pulse forming switches that are connected to an antenna array to generate carrier based (pulsed sinusoid) waveforms. The delay difference resolution and maximum delay difference between the impulse sequences at adjacent channels are 180ps and 880ps, respectively. The UWB pulse forming switches achieve sub-200ps rise/fall time with isolation higher than 40dB and insertion loss better than 4dB between DC-6GHz. The proposed UWB timed array architecture eliminates the need for area and power hungry true time delay circuitry that would have been otherwise needed for beam-forming.

A CMOS UWB Camera with 7×7 Simultaneous Active Pixels

Intelligent environments significantly impact human daily lives through embedded sensing and actuating systems. Wireless sensors that can provide non-contact radio information are indispensable. Impulse radar is positioned as a favorable candidate in monitoring and sensing objects [1-3]. The impulse radio is inherently multipath immune and suitable for precision ranging. Accurately detecting signals with low power impulse radios imposes design challenges to impulse radar receivers. In this work, a direct-sampling receiver is proposed and implemented for an impulse radar system. It can support GHz instantaneous bandwidth and more than 100GS/sec equivalent sampling rate through the high-speed sampling circuits and on-chip timing circuitry. The wide bandwidth scattering time-domain waveforms in the radio interaction between the object and radar can be sampled and digitized by the receiver. It achieves precise measurement of time of arrival (TOA) in a radar system and expands the scalability towards antenna arrays for detection of direction of arrival (DOA) [4].