Showing papers by "Nils Weimann published in 2021"

Connecting Chips With More Than 100 GHz Bandwidth

Abstract: Connecting chips within a module is a basic requirement in transforming MMIC performance to system functionality. More and more applications demand for operation at high mm-wave frequencies or with ultra-large bandwidth. While semiconductor devices have seen tremendous progress in terms of their frequency limits, the chip interconnects lag behind and often form the bottleneck in realizing such systems. This paper reviews the broadband potential of the most common interconnect types in use and their performance demonstrated so far, covering wirebonding, approaches with chips embedded in a substrate, and flip-chip. Additionally, as an intermediate solution between system-on-chip and system-in-a-package, semiconductor hetero-integration on the chip-level is included. As is discussed, bond wire interconnects are most limited in bandwidth among the four types and reach the 100 GHz band only at the expense of narrowband characteristics. Dedicated embedded-chip packaging techniques show significantly better performance, bandwidths in the order of 100 GHz have been shown in the literature. Flip-chip has clearly the highest potential, interconnects covering the range from DC to 500 GHz have been demonstrated and are presented in the paper. Hetero-integration on the chip proves to allow for very broadband interconnects between elements and circuits on the compound chip as well: For an InP-on-BiCMOS process 325 GHz bandwidth were achieved and even higher values seem to be feasible.

Broadband THz Detection Using InP Triple-Barrier Resonant Tunneling Diode With Integrated Antenna

Abstract: A broadband THz detector consisting of a triple-barrier InP Resonant Tunneling Diode (RTD) with a monolithically integrated circularly polarized spiral antenna is designed, fabricated, and measured at room temperature. A free space measurement setup is utilized for far-field characterization. The detector (evaluated at zero-bias) is illuminated by a chopped continuous wave signal in the 220–330 GHz band, and the direct detection scheme consists of a lock-in amplifier in voltage mode readout. The measured average responsivity R V is in the range of 750 V/W with a peak of 900 V/W at 257.5 GHz, with the lowest calculated NEP of 2.5 pW/√Hz.

A Modular MIMO Millimeter-Wave Imaging Radar System for Space Applications and Its Components

Abstract: This article presents the design and prototyping of components for a modular multiple-input-multiple-output (MIMO) millimeter-wave radar for space applications. A single radar panel consists of 8 transmitters (TX) and 8 receivers (RX), which can be placed several times on the satellite to realize application-specific radar apertures and hence different cross-range resolutions. The radar chirp signals are generated by SiGe:C BiCMOS direct-digital-synthesizers (DDS) in the frequency range of 1 to 10.5GHz with a chirp repetition rate of 30dB gain with noise figure values of 9dB, respectively. The MIMO radar utilizes patch antenna arrays on organic multilayer printed circuit boards (PCB) with 18dBi gain and 18∘ half power beamwidth (HPBW). Generation of power supply and control signals, analog-to-digital conversion (ADC), and radar signal processing are provided centrally to each panel. The radar supports detection and tracking of satellites in distances up to 1000m and image generation up to 20m, which is required to support orbital maneuvers like satellite rendezvous and docking for non-cooperative satellites.

There is Plenty of Room for THz Tunneling Electron Devices Beyond the Transit Time Limit

Abstract: The traditional transmission coefficient present in the original Landauer formulation, which is valid for quasi-static scenarios with working frequencies below the inverse of the electron transit time, is substituted by a novel time-dependent displacement current coefficient valid for frequencies above this limit. Our model captures in a simple way the displacement current component of the total current, which at frequencies larger than the inverse of the electron transit time can be more relevant than the particle component. The proposed model is applied to compute the response of a resonant tunneling diode from 10$\,$GHz up to 5$\,$THz. We show that tunneling electron devices are intrinsically nonlinear at such high frequencies, even under small-signal conditions, due to memory effects related to the displacement current. We show that these intrinsic nonlinearities (anharmonicities) represent an advantage, rather than a drawback, as they open the path for tunneling devices in many THz applications, and avoid further device downscaling.

THz Detectors and Emitters with On-Chip Antenna aligned on Hyper-Hemispherical Silicon Lenses

Abstract: On-chip antennas with radiation towards the substrate are affected by modest coupling performance to a free-space path. (Hyper-)hemispherical silicon lenses can improve the efficiency of quasi-optical emission and detection even at THz frequencies. This approach requires an alignment accuracy in the $\mu\mathrm{m}$ -scale at THz frequencies. In this contribution, we report on the benefit of hyper-hemispherical silicon lenses in terms of relaxed alignment accuracy needs. We present the impact of alignment on quasi-optical measurements using indium phosphide resonant-tunneling diodes. The main components of the resulting setups are discussed while the effect of alignment is quantitatively evaluated for both, hemispherical and hyper-hemispherical silicon lenses. Moreover, design rules and concepts for a heterointegrated system are derived on consecutive observations.

There is Plenty of Room for THz Tunneling Electron Devices Beyond the Transit Time Limit

Abstract: The traditional transmission coefficient present in the original Landauer formulation, which is valid for quasi-static scenarios with working frequencies below the inverse of the electron transit time, is substituted by a novel time-dependent displacement current coefficient valid for frequencies above this limit. Our model captures in a simple way the displacement current component of the total current, which at frequencies larger than the inverse of the electron transit time can be more relevant than the particle component. The proposed model is applied to compute the response of a resonant tunneling diode from 10 GHz up to 5 THz. We show that tunneling electron devices are intrinsically nonlinear at such high frequencies, even under small-signal conditions, due to memory effects related to the displacement current. We show that these intrinsic nonlinearities (anharmonicities) represent an advantage, rather than a drawback, as they open the path for tunneling devices in many THz applications, and avoid further device downscaling.

A W-Band Transceiver Chip for Future 5G Communications in InP-DHBT Technology

Abstract: This paper presents a W-band transceiver chip using InP-DHBT technology for future 5G application. It consists of a transceiver switch, a medium power amplifier (MPA) and a low noise amplifier (LNA) in 0.8 µm InP-DHBT technology. The switch operates from 75 GHz to 110 GHz and simulation results show more than 20 dB isolation and 1 dB output power (P 1dBout ) of 15 dBm. The measured MPA exhibits 16 dBm saturated output power (P sat ) with 18 % power added efficiency (PAE) at 90 GHz. The measured LNA small signal gain is higher than 30 dB from 75 to 110 GHz and the measured noise figure values are below 9 dB. After integrating individual components (switch, LNA and PA), the entire transceiver chip achieves a measured isolation of more than 15 dB. The entire circuit consumes total 280 mW DC power. The chip area is only 2.5x1.5 mm2, To the knowledge of the authors, this is the first monolithically integrated transceiver covering the W-band for future 5G communication reported so far.

Design of a 1-to-4 Subarray Element for Wireless Subharmonic Injection in the THz Band

Abstract: This paper presents an on-chip 1 to 4 subarray element for wireless subharmonic injection (WSI) in the context of antenna-in-antenna THz oscillators. The proposed antenna receives the third-order subharmonic injection signal (SIS) at 100 GHz from one side and radiates the 300 GHz fundamental oscillation signal (FOS) to the opposite side, which performs like a subharmonic transmitarray. Each element is consisted of a single SIS receiving antenna (Receiver antenna, RA) connected with a $2\times 2$ FOS array (Transmitter antenna, TA). By positioning more FOS antenna around the single SIS antenna, the element spacing at 300 GHz is shorted within one wavelength which inhibits the grating lobe. Through tuning the distance of the FOS array element, the surface wave in the thick indium phosphide (InP) substrate is also reduced to some degree. The simulation results show that the maximum radiation efficiency of the designed chip antenna structure is better than 50% in both the 100 GHz and the 300 GHz band. The conjugate impedance matching in the dual-band is achieved according to the active element requirement. Utilizing the antenna proposed in this work, a low injection loss is verified in the periodical boundary based WSI simulation.