Ultra-High Sensitivity MEMS Pressure Sensor Utilizing Bipolar Junction Transistor for -1…+1 kPa

The theoretical model and experimental characteristics of ultra-high sensitivity MEMS pressure sensor chip for the range of -1...+1 kPa utilizing a novel electrical circuit are presented. The electrical circuit uses piezosensitive differential amplifier with negative feedback loop (PDA-NFL) based on two bipolar-junction transistors (BJT). The BJT has a vertical structure of n-p-n type (V-NPN) formed on a non-deformable chip area. The circuit contains eight piezoresistors located on a profiled membrane in the areas of maximum mechanical stresses. The circuit design provides a balance between high pressure sensitivity (S = 44.9 mV/V/kPa) and fairly low temperature dependence of zero output signal (TCZ = 0.094% FS/°C). Additionally, high membrane burst pressure of P = 550 kPa was reached.