Peiyu Chen

A 30GHz impulse radiator with on-chip antennas for high-resolution 3D imaging

This paper reports a 30-GHz impulse radiator utilizing an injection-locked asymmetric cross-coupled voltage-control-oscillator (VCO) with on-chip bow-tie antennas. The impulse radiator converts a digital trigger signal to a radiated impulse with a variable pulse-width down to 60psec with peak EIRP of 15.2dBm without using any lens. Coherent spatial pulse combining is demonstrated by using two widely spaced radiators. A timing jitter of the 216fsec for the combined signal is measured. The impulse radiator has the capability of producing 3D images with depth resolution of 33μm at 25cm of target distance in the air. The chip is implemented in a 0.13μm SiGe BiCMOS process technology. The total die area is 2.85mm2 with maximum power consumption of 106mW.

A 4ps amplitude reconfigurable impulse radiator with THz-TDS characterization method in 0.13µm SiGe BiCMOS

This paper reports a fully integrated impulse radiator with the capability of radiating impulses with 4ps FWHM and reconfigurable amplitude. The peak radiated power at 54GHz is 8.7dBm with a 13.6dBm peak EIRP. A Non-Linear Q-Switching Impedance (NLQSI) technique is introduced to generate impulses and control their amplitudes. Furthermore, a two-bit impulse amplitude modulation is achieved through an on-chip four-way impulse combiner, which also attenuates parasitic-induced low-frequency radiation. In addition to performing frequency-domain measurements, for the first time, an ultra-wideband THz Time-Domain Spectroscopy (THz-TDS) system is utilized to characterize the radiated signal in time-domain. The radiated impulse has an SNR>1 bandwidth of more than 160GHz. The fully-integrated impulse radiator is implemented in a 0.13μm SiGe BiCMOS process. It has a die area of 1mm2 and it consumes 170mW.

A Nonlinear Q-Switching Impedance Technique for Picosecond Pulse Radiation in Silicon

This paper presents a nonlinear Q-switching impedance (NLQSI) technique for picosecond pulse radiation in silicon. A prototype chip is designed with four NLQSI-based impulse generation channels, which can produce picosecond pulses with a reconfigurable amplitude. An on-chip impulse-coupling scheme combines the outputs from four channels and delivers the combined signal to an on-chip antenna. In addition, an asynchronous optical-sampling measurement system is used to characterize the radiated picosecond pulses in the time domain. The prototype chip can radiate 4-ps pulses with an SNR > 1 bandwidth of 161 GHz. Furthermore, pulse amplitude modulation is experimentally demonstrated. The prototype chip is fabricated in a 130-nm SiGe BiCMOS process technology with a die area of 1 mm2.

Gone in a Picosecond: Techniques for the Generation and Detection of Picosecond Pulses and Their Applications

The technology for generating and detecting electromagnetic waves has evolved significantly over the last 120 years. In the early 1890s, Guglielmo Marconi used a spark-gap transmitter to build a wireless telegraphy system. In his design, he charged a capacitor to a high dc voltage and connected it to a parallel combination of an inductor, a second capacitor, and an antenna through an air gap. In this configuration, when the dc voltage of the first capacitor reaches the breakdown voltage of the gap, the air in the gap ionizes and reduces the resistance across the gap. This results in a large step voltage applied to the parallel combination of the inductor, second capacitor, and the antenna and converts the dc energy stored in the first capacitor to a damped oscillation at a low megahertz range that is radiated from the antenna. Marconi?s design used the spark gap as a fast high-voltage switch. The technology for generating electromagnetic waves then evolved further with the invention of vacuum tubes in the mid-1920s. Vacuum tubes enabled oscillatory signals to be amplified in the megahertz range and provided enough bandwidth for transferring audio signals.

High efficiency carbon nanotube thread antennas

Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. These measurements are crucial for any practical application of CNT materials in wireless communication. In this letter, we report a measurement technique to accurately characterize the radiation efficiency of λ/4 monopole antennas made from the CNT thread. We measure the highest absolute values of radiation efficiency for CNT antennas of any type, matching that of copper wire. To capture the weight savings, we propose a specific radiation efficiency metric and show that these CNT antennas exceed coppers performance by over an order of magnitude at 1 GHz and 2.4 GHz. We also report direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical a...

3-D Radar Imaging Based on a Synthetic Array of 30-GHz Impulse Radiators With On-Chip Antennas in 130-nm SiGe BiCMOS

We report a 30-GHz impulse radiator chip for high-resolution 3-D radar imaging. In this paper, an asymmetrical topology in the cross-coupled pulsed VCO is introduced to minimize timing jitter of radiated impulses to 178 fs, which enables highly efficient spatial combining. The coherent combining over the air has been performed with two widely spaced impulse radiators. The shortest full-width-at-half-maximum pulsewidth of 60 ps is recorded. 3-D images of various metallic objects and dielectric objects are produced using a custom-designed synthetic array imaging system. A depth resolution of 9 mm and a lateral resolution of 8 mm at a range of 10 cm have been achieved. The impulse radiator was implemented in a 130-nm SiGe BiCMOS process technology with an area of 2.85 mm2 and an average power consumption of 106 mW.

Time-Domain Characterization of Silicon-Based Integrated Picosecond Impulse Radiators

A direct time-domain characterization of silicon-based integrated picosecond impulse radiators using a femtosecond laser-gated optoelectronic sampling technique is developed. In the proposed system, a 1550 nm femtosecond laser source is used to generate an electrical trigger signal fed to a picosecond impulse radiator, and another synchronized 1550 nm femtosecond laser source is used to gate a photoconductive detector. Technical challenges are addressed to synchronize the silicon radiators with the optoelectronic sampling system. This paper presents the details of the proposed technique and characterization of 4.8 ps impulses radiated by a custom silicon chip.