A 0/20-dB Step Linearized Attenuator with GaAs-HBT Compatible, AC-Coupled, Stack Type Base-Collector Diode Switches

This paper describes a GaAs-HBT compatible, base-collector diode step attenuator for 3.5-GHz band wireless applications. The attenuator uses an AC-coupled, stacked type diode switch topology featuring high power handling capability with low bias current operation. Compared to a conventional diode switch topology, the topology can improve the capability of more than 6 dB with the same bias current. In addition, successful incorporation of a shunt diode linearizer into the attenuator gives the IM3 distortion improvement of more than 7 dB in the high power ranging from 16 dBm to 18 dBm in the 20-dB attenuation mode. Measurement results are as follows: 1.4/20-dB insertion loss, and 20-dBm power handling capability (P
_0.2dB
) and low bias current of 3.8/6.8 mA in thru/attenuation modes at 5 V