A phase coherent DC-25 GHz 6-bit SiGe BiCMOS step attenuator with IP1dB >20 dBm

Official URL: https://dx.doi.org/10.23919/EuMIC50153.2022.9783738

This paper presents a 6-bit step attenuator with high linearity and very low RMS amplitude and phase errors from DC to 25 GHz. The presented attenuator was designed with hybrid Π/T-type attenuation blocks. Isolated NMOS (iNMOS) devices were utilized instead of conventional NMOS transistors since iNMOS devices have fewer parasitics than its counterpart. This feature provides to keep the slope of the insertion loss (IL) constant and improves the power handling capability of the designed attenuator. This design was fabricated with IHP's 130 nm SiGe BiCMOS technology. The measured attenuator has a dynamic range of 23.96 dB with 0.38 dB fine steps. The RMS amplitude error of the designed attenuator is <0.38 dB from DC to 25 GHz. The maximum measured RMS phase error is 2.4° at 25 GHz. The measured IP 1dB is > 20 dBm at 7.5 GHz and 12.5 GHz.