August 5, 2020
NTT Corporation (Head Office: Chiyoda-ku, Tokyo; President and CEO: Jun Sawada; hereinafter “NTT”) has achieved a world’s first in applying a neutralization circuit*1 to an amplifier circuit in the 500 GHz band by using an inductor component to neutralize the transistor’s parasitic capacitance that limits amplifier frequency. With this technology, NTT has successfully achieved a 20 dB high-gain amplifier IC in the 500 GHz band.
The 500 GHz band is a high-frequency band known as terahertz waves*2 that is expected to have application to sensing and other fields. To use such a frequency band with frequencies higher than those of microwaves and millimeter waves, the development of a high-gain amplifier IC has been anticipated.
NTT has achieved a 500 GHz band amplifier IC applying original neutralization circuit technology using an InP*3-based HEMT*4 and has confirmed a power amplification factor (gain) of 20 dB, which is 2.5 times greater than currently reported gain in 500 GHz band amplifiers. This technology is therefore expected to help improve the accuracy of weather forecasting for extreme events such as typhoons and torrential rain. The plan is to present detailed information on this technology via the newly established Late News*5 system at IEEE International Microwave Symposium 2020 (IMS2020) to be held online on the Internet from August 4 United States time.
Terahertz waves that include the 500 GHz band constitute a frequency band that exhibits little interference with other systems or natural radiation. This band features electrical characteristics that enable accurate determination of water vapor, oxygen concentrations, etc., so applying it in addition to the frequencies (7 GHz – 80 GHz) currently being used in meteorological observations is expected to improve the accuracy of weather forecasting such as for typhoons and torrential rain.
This research has achieved a 500 GHz band amplifier IC applying original neutralization circuit technology using an InP-HEMT and has successfully achieved a 20 dB high-gain amplifier IC. This is 2.5 times the gain reported so far for 500 GHz band amplifier ICs, which makes this a promising technology for improving the accuracy of weather forecasting especially for extreme events such as typhoons and torrential rain.
This amplifier IC can perform signal amplification with a high gain of 20 dB in the 500 GHz band, which up to now has been difficult to achieve anywhere in the world. In this capacity, we expect it to find application in a variety of fields such as imaging and large-capacity wireless communications in addition to sensing. Going forward, the deepening of this technology will contribute to the advancement of science and technology that can make everyone’s life safer and more secure, more prosperous, and more convenient while giving hope for the future of mankind.
An amplifier IC using an InP-HEMT having superior high-speed and high-gain characteristics has been achieved. In conventional amplifiers, the operating frequency has been held to about 60% of transistor performance (fMAX*6). Against this background, NTT proposed the neutralization circuit shown in Figure 1. This circuit uses an inductor component to neutralize the transistor’s parasitic capacitance component, which is a factor limiting amplifier frequency. NTT constructed a prototype amplifier IC (Figure 2) applying this circuit technology to terahertz waves and successfully achieved amplifier operation with a gain of 20 dB in the 500 GHz band exceeding 80% of fMAX (Figure 3). This work was supported in part by the FY2018 – FY2020 “Research and Development of Basic Technology for Terahertz Sensing Systems” R&D program of the Ministry of Internal Affairs and Communications.
This achievement will be presented at International Microwave Symposium 2020 held online from August 4 under the title “475-GHz 20-dB-Gain InP-HEMT Power Amplifier Using Neutralized Common-Source Architecture” from 11:00 AM, August 5 local time.
|Technical Session||Th2B: Late-breaking News from Terahertz Frontier|
|Time||Can be viewed from 11:00 AM, August 5 local time|
|Title||475-GHz 20-dB-Gain InP-HEMT Power Amplifier Using Neutralized Common-Source Architecture|
|Conference Web site||https://ims-ieee.org/
NTT Science and Core Technology Laboratory Group
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