Eiji Suematsu

A fiber optic/millimeter-wave radio transmission link using HBT as direct photodetector and an optoelectronic upconverter

The performance of a fiber optic subcarrier link using an HBT as a direct photodetector and an optoelectronic up-converter in 50 GHz band has been experimentally investigated at a wavelength of 0.83 /spl mu/m. From comparison with the performances of links using other MMIC-compatible photodetectors and with that of a high speed PIN-photodetector, this paper shows that the HBT-photodetector is superior to the other MMIC compatible photodetectors (MSM and HEMT). It is also shown that HBT not only has a high photodetection ability in the millimeter-wave band but also provides low conversion loss between a microwave subcarrier modulated by an optical signal and a millimeter-wave carrier. Also demonstrated are video FM-subcarrier transmission and 140 Mbps QPSK digital radio transmission using an HBT optical/RF transducer. At transducer transmission power of around -20 dBm, the HBT optical/RF transducer allows 50 GHz band radio transmission over optical fiber to achieve a weighted SNR of more than 50 dB and a data rate of 140 Mbps in indoor application.

60GHz ultra compact transmitter/receiver with a low phase noise PLL-oscillator

In this paper, we present a transmitter and a receiver for a millimeter-wave video transmission system. The size of each is 110 mm/spl times/55 mm/spl times/23 mm, as a result of using an antenna-integrated millimeter-wave module and a filter-integrated SHP (sub-harmonically pumped) mixer MMIC. Both transmitter and receiver have a local signal of 29.5 GHz, for up/down-conversion, which is generated by multiplying a signal from a 1.8 GHz PLL-oscillator. A low phase noise of -103 dBc/Hz at 100 kHz offset was achieved.

Frequency response of HBTs as photodetectors

The frequency response of HBT photodetectors fabricated by the MMIC HBT process has been experimentally investigated. 3-dB bandwidths of 2 GHz and more than 20 GHz have been achieved in a CE (common emitter) HBT and a CB (common base) HBT, respectively. The photoresponse of the CEHBT is approximately 25 dB higher than that of the CBHBT at 1 GHz. The CEHBT has a higher signal-to-noise ratio than a PIN/50- Omega FET amplifier at 10 GHz.<<ETX>>

Wall-Hanging Type of Self-Complementary Spiral Patch Antenna for Indoor Reception of Digital Terrestrial Broadcasting

A printed spiral antenna with a self-complimentary configuration was developed. This antenna consists of spiral shaped metal strips and slots provided on ground planes as their counterparts. For balanced and unbalanced feeds, two types of antenna configurations such as single and twin spirals were fabricated and their antenna performances were investigated. From evaluation of carrier noise ratio of digital terrestrial broadcasting channels at UHF band, it was confirmed that the presented self-complimentary spiral antenna has capability to apply into an indoor terrestrial broadcasting TV antenna

Analytical model for electrical and thermal transients of self-heating semiconductor devices

Transients of self-heating semiconductor devices are theoretically investigated based on a feedback circuit model, which is composed of three sub-circuits describing the isothermal electrical characteristics, thermal impedance, and temperature dependence of the electrical characteristics of the devices, respectively. Analytical expressions of the frequency and transient responses have been derived for both the electrical and thermal characteristics of self-heating devices, yielding accurate methods to extract the thermal time constant in both the time and frequency domains. The model is verified by the transient electrical-response measurement of a GaInP/GaAs heterojunction bipolar transistor.

A comparison of noise performance between a PIN diode and MMIC HEMT and HBT optical receivers

The noise performance of MMIC (monolithic microwave integrated circuit) HEMTs (high electron mobility transistors) and HBTs (heterojunction bipolar transistors) are experimentally compared with those of conventional PIN photodiodes. The HEMTs and HBTs are fabricated using a conventional MMIC process. These devices are characterized using a modified electrooptic on-wafer probe station, and a LiNbO/sub 3/ optical external modulator. The attained signal-to-noise ratios of HEMT, HBT, and PIN detectors at a signal frequency of 1 GHz, an optical carrier of 0.83 mu m, and a frequency bandwidth of 1 MHz are 52.3 dB, 55.9 dB, and 54.1 dB, respectively.<<ETX>>

60GHz-band low noise amplifier and power amplifier using InGaP/GaAs HBT technology

In this paper, we present a 60 GHz-band low noise amplifier (LNA) and a 60 GHz-band power amplifier (PA) utilizing high performance InGaP/GaAs HBTs. The InGaP/GaAs HBTs feature a highly doped base layer, a self-aligned base contact and an undercut collector mesa structure in order to achieved low noise and high gain in the millimete-wave band. By adjusting the collector current of each HBT in the LNA to the optimum value a noise figure as low as 5.8 dB with a gain of more than 25 dB was obtained. The PA exhibited a linear gain of more than 15 dB with P1dB of 13 dBm in the 60 GHz-band.

Digital and analog satellite/millimeter-wave transmission link

The performance of a digital and analog satellite/millimeter-wave transmission link has been experimentally investigated in terms of the C/N ratio. This system, which wirelessly connected TV and its antenna using millimeter-wave signals, consists of a commercially available low noise converter with a parabola antenna and a millimeter-wave transmitter/receiver. The transmitter/receiver has built-in up/down-converters, which enables multi-channel TV signals with more than 100 channels to transmit and receive with air-interface bandwidth of about 1 GHz in the 60 GHz band. An output power of 1 dBm with a 20 dBi horn antenna in the transmitter and a noise figure of 11 dB with the same horn antenna in the receiver, make possible millimeter-wave multi-channel video transmission through the walls between two rooms in a Japanese house.

Fundamental properties of HEMT photodetector for use in fiber optic links

A monolithic integrable HEMT photodetector is experimentally investigated for use in fiber optic subearrier transmission links. The frequency response and noise performance of the IIEMT photodetector are discussed in this paper. The results include a response of 1.0 A/W and a signal-to-noise ratio of 49.8 dB (BW = 1 MHz, Popt = ¿8.5 dBm), at a subcarrier frequency of 1 GHz. This photodetector is expected to contribute to high-performance and cost-effective optical/RF transducers.

Noise performance of MMIC HBTs as photodetectors

The radio-frequency (RF) responsivity and noise performance of HBTh used as photodetectors in the microwave/millimeter-wave band are reported for the first time. The RF responsivity for a common base HBT (CBHBT) shows a 3-dB bandwidth (f-3dB) of more than 20 GHz. The CBHBT with floating emitter operate as a base-collector junction photodiode. The noise performance of a CBHBT-FET receiver depends on the noise characteristics of the FET amplifier that follows the CBHBT. A common emitter HBT (CEHBT) operate as a transimpedance amplifier with a base-collector junction photodiode. This device enables a lower noise floor than that of the PIN-FET receiver in a 50-¿ system. For a CEHBT used as a photodetector, equivalent input noise currents of 12 and 20 PA/¿Hz are obtained at 10 and 20 GHz, respectively, by noise floor measurements and an equivalent circuit model.