Design and measurement of 0.1 – 4.5 GHz SiGe BiCMOS MMIC digital step attenuator

The design and measurement of 0.1 – 4.5 GHz 5-bit MMIC digital step attenuator (DSA) are presented. The MMIC DSA is fabricated with 0.25 um SiGe BiCMOS process and includes integrated driver providing serial/parallel control. The main features of MMIC DSA are as follows: wideband performances (it covers L-, S- and partially C-band); a good input and output return losses (less than 12 dB and 14 dB, respectively); small phase variation (RMS phase error less than 5.3°); integrated driver; small size (1.4×0.6 mm²); low power consumption Performances of MMIC DSA designed are compared with its commercial counterparts.

I. Introduction

Microwave digital step attenuators (DSA) are widely used in transmit/receive modules (TRMs) applied for radar and radio-relay systems [1]. Microwave TRMs usually use microwave monolithic integrated circuits (MMICs) manufactured with A3B5 semiconductors technologies (GaAs and GaN). However, now the circuits for controlling the microwave signal's amplitude and phase in TRM (attenuators, phase shifters, and switches) are increasingly fabricated with SiGe BiCMOS technology [2], [3]. In comparison with A3B5, this process provides a higher integration scale, smaller weight, size and cost, and lower power consumption. In addition, the important advantage of SiGe BiCMOS technology is the ability to combine analog and complex digital control circuits (drivers) in a single fabrication process. Contrary, the use of A3B5 manufacturing technology for implementing digital drivers is much more complicated, enlarges the development cost, increases MMIC size and limits control capabilities [2], [3].