A full-monolithic LNA in 0.18/spl mu/m SiGe: performance variation due to ESD protection

This paper reports design of a 5GHz full-monolithic LNA implemented in a 0.18/spl mu/m 90GHz f/sub T/ SiGe process with and without RF ESD protection. The RF ESD protection is provided by a simple diode ESD protection structure for 2kV ESD protection. Influences of the RF ESD protection structure on the LNA performance were investigated. Measurement results show substantial performance degradation for the LNA with ESD protection compared with that without ESD protection: i.e. a 4dB decrease in gain from 21.75dB dropping to 17.50dB and 0.3dB increase in noise figure from 2.53dB to 2.82dB. Laser cut was used to remove the RF ESD protection device from the LNA circuit in measurements.