Design of differential low-noise amplifier with cross-coupled-SCR ESD protection scheme

The pin-to-pin electrostatic discharge (ESD) stress was one of the most critical ESD events for differential input pads. The pin-to-pin ESD issue for a differential low-noise amplifier (LNA) was studied in this work. A new ESD protection scheme for differential input pads, which was realized with cross-coupled silicon-controlled rectifier (SCR), was proposed to protect the differential LNA. The cross-coupled-SCR ESD protection scheme was modified from the conventional double-diode ESD protection scheme without adding any extra device. The SCR path was established directly from one differential input pad to the other differential input pad in this cross-coupled-SCR ESD protection scheme, so the pin-to-pin ESD robustness can be improved. The test circuits had been fabricated in a 130-nm CMOS process. Under pin-to-pin ESD stresses, the human-body-model (HBM) and machine-model (MM) ESD levels of the differential LNA with the cross-coupled-SCR ESD protection scheme are >8 kV and 800 V, respectively. Experimental results had shown that the new proposed ESD protection scheme for the differential LNA can achieve excellent ESD robustness and good RF performances.