  Characteristics of high sensitivity MEMS pressure sensor chip for 10 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 experimental results prove that
pressure sensor chip PDA-NFL with 4.0x4.0 mm2 chip area has sensitivity S =
7.8...12.4 mV/V/kPa with nonlinearity of 2KNL = 0.14...0.38 %/FS (pressure is
applied from the back side of pressure sensor chip).
