Sizing Ground Taps to Minimize Substrate Noise Coupling in RF LNAs

Abstract

The influence of the sizing of ground taps on the noise injected into a 1.5GHz low noise amplifier (LNA), by a stepped buffer, for a heavily doped CMOS process is quantitatively examined. Precise modeling provides good agreement between measurements and simulations. A 10dB increase in isolation was achieved by scaling the area of the substrate contact by a factor of 400, and by increasing the proximity of the contacts to the sensitive transistors