475-GHz 20-dB-Gain InP-HEMT Power Amplifier Using Neutralized Common-Source Architecture

We developed a 475-GHz power amplifier (PA) by using our in-house 60-nm InP-HEMT technology with
$f_{T}$
and f
MAx
of 320 and 700 GHz, respectively. To attain the positive gain at 475 GHz with this relatively low-/f
MAx
InP-HEMT, a neutralization technique was introduced to each common-source FET (CSF) stage of the PA's unit amplifier (UA). To attain high gain, the UAs are cascaded in three stages in the PA. To obtain large output power, a 4-way power-combining is used in the output stage of the PA. The fabricated PA shows superb small signal gain and output power of 20.2 dB and -1.1 dBm at 480 and 475 GHz, respectively. To the best of our knowledge, this is the first study on a solid-state amplifier in the WR2.2 band (330–500 GHz) with neutralization and the first reported PA with power-combining in this band. The fabricated PA shows state-of-the-art gain and output power with respect to previously reported WR2.2 amplifiers.