Piezojunction effect of a planar n-p-n transistor for transducer aims

Measurements of the piezojunction effect of planar n-p-n transistors are reported. The principle for a pressure transducer that makes use of the variation of the base-emitter voltage as a function of the pressure is described. The transducer uses a balanced configuration to lower the temperature sensitivity. Together with the transducer transistors, an adjustment circuit and an output amplifier are integrated on the same chip. Measurements of the complete transducer show a sensitivity of 2 mV per gram exercised force.