Shengling Deng

Packaging of Dual-Mode Wireless Communication Module Using RF/Optoelectronic Devices With Shared Functional Components

This paper reports the design, fabrication, and testing of a compact radio-frequency (RF)/ free space optical (FSO) dual mode wireless communication system. A modified split dual-director quasi-Yagi antenna is integrated with optical transmitter and receiver by sharing layout structural components. Bare die vertical-cavity surface-emitting laser (VCSEL) and P-i-N photodiode (PIN) are placed on antenna director pads and wire bonded to printed circuit board (PCB)-mounted laser driver and transimpedance amplifier (TIA) circuits. Detailed analysis of coupling between RF channel and associated electrical connections for the FSO channel is presented using commercial simulation tools to predict its impact on link degradation. Although crosstalk appears between RF and optical channels, the prototyped system demonstrated dual-mode high-rate communication capability with measured 2.5 Gb/s data rate in FSO link. Variations in RF subsystem features due to coupling from the FSO subsystem is estimated through radiation pattern measurement using near-field scanner.

A 5Gb/s 7-channel current-mode imaging receiver front-end for free-space optical MIMO

A 7-channel diversity receiver front-end based on current-summing for broadband free-space optical (FSO) MIMO communication is presented in this paper. This diversity receiver is designed for flip-chip bonding to a custom InGaAs metal-semiconductor-metal (MSM) photodetector array. Each channel employs a low input-impedance current mirror (CM) as the input stage, which allows the implementation of direct current-summing for equal-gain combining (EGC). The summed-up current signal drives a second stage transimpedance amplifier (TIA) to generate the output voltage. Implemented in an 180 nm CMOS technology, a total gain of 58.5 dBΩ, and −3dB bandwidth of 3.7 GHz for 0.25 pF photodiode capacitance is achieved. The power consumption for a single front-end amplifier circuit is 4.2 mW, and for the second stage TIA is 10.3mW with a single 1.8V supply.

Ultrashort SiGe Heterojunction Bipolar Transistor-Based High-Speed Optical Modulator

A graded base SiGe HBT optical modulator has high-speed, high optical modulation efficiency, small footprint. In this paper, we present our work in the design and modeling of an HBT optical modulator, its driver circuit and fabrication and integration. A high-efficient HBT electro-optical (EO) modulator with π phase-shift length of 22.6 μm is investigated. The speed of this modulator is calculated to be 30 Gb/s. To verify the functionality of HBT structure as an EO modulator, an 80 Gb/s serializer and driver with an HBT modulator is fabricated by the IBM 8HP BiCMOS process, which has much higher speed but lower modulation efficiency.

Radio-Optical Dual-Mode Communication Modules Integrated With Planar Antennas

This paper presents new results on integrated devices for radio and free-space optical dual-mode communication. Two novel hybrid packaging schemes using two different microwave printed antenna designs are presented for the integration of radio-optical front-end circuits on a planar compact printed circuit board with shared electrical and structural components. Full-wave electromagnetic (EM) simulations are presented for antenna optimization to minimize EM interference between the radio and optical circuits. A hybrid radio-optical package design is developed, prototyped, and experimentally studied using a modified quasi-Yagi antenna with split directors to form pads for opto-electronic device integration. Dual-mode link connectivity is investigated in simulations and experiments. A data rate of 2.5 Gb/s is demonstrated for the optical channel despite 15-20-dB signal coupling between the optical and microwave circuits.

Antenna integration with laser diodes and photodetectors for a miniaturized dual-mode wireless transceiver

In this paper, a dual split director quasi-yagi antenna is introduced for RF/FSO integration. Bare die laser diodes and photodetectors are assembled on the antenna directors on the duroid substrate. Coupling between RF and optical dual mode wireless communication system is analyzed.

Integrated Laser Diodes and Photodetectors with Antenna for Dual-Mode Wireless Communication

Bare die laser diodes and photodetectors are placed in the radiation path of quasi-Yagi antenna on Duriod substrate as additional antenna director. Independent operation is observed for dual-mode wireless communication.

Design of an integrated high-speed HBT-based electroabsorption modulator and driver in SiGe BiCMOS technology

Monolithic optoelectronic integrated circuits are a primary focus of research for high-speed optical communication system development. Standard silicon processes provide a cost effective way for electro-optic system integration. This paper presents a monolithic optical modulator and driver design based on 130nm SiGe BiCMOS technology. Post-layout simulation results demonstrate that the modulator achieves a switch frequency of 10GHz.

Numerical investigation of a SiGe HBT electro-optic modulator

We analyzed an electro-optic modulator consisting of a heterojunction bipolar transistor (HBT) with graded SiGe composition in the base. Simulation shows single mode operation is attainable with an interaction length Lp of 40.8μm.