A.I. Lee, S.I. Tolstolutsky, D.A. Truhov
This paper presents the results of design and measurement of 26.5–40-GHz low-loss digital attenuator. The attenuator is controlled by MESFET, 0.8 µm. The control voltages used for the MESFET switches are 0 and -5 volts.
Several digital attenuator designs were reported in the literatures, distributed T switchable attenuators or Pi attenuators. However this design leads to high level insertion loss, when we used MESFET with gate more than 0.25 µm. In this paper, we describe an broadband 6-bit digital attenuator implemented in 0.8 µmGaAs MESFET MMIC with low insertion loss.
The attenuator chip with dimensions 2.6 × 1.3 mm2 has been made to provide control signal amplitude on range from 0 to 31.5 dB with step 0.5dB. The input and output VSWRs of the attenuators are better than 1.85:1 over all attenuation states and frequencies.