Temperature compensation system for piezoresistive pressure sensor

A system for sensing pressure comprising:

• a pressure sensing means comprising first, second, third, and fourth piezoresistive means, each having first and second terminal means and each having a high temperature coefficient of resistivity, said first piezoresistive means second terminal means being electrically connected to said second piezoresistive means first terminal means said second piezoresistive means second terminal means being electrically connected to said third piezoresistive means first terminal means, and said third piezoresistive means second terminal means being electrically connected to said fourth peezoresistive means first terminal means, said second piezoresistive means second terminal means and third piezoresistive means first terminal means being adapted to receive a input voltage of a first polarity, said first piezoresistive mean second terminal means and said second piezoresistive means first terminal means being electrically connected to a first output terminal means, and said third piezoresistive means second terminal means and said fourth piezoresistive means first terminal means being electrically connected to a second output terminal means;
• and
• first and second null balance means for maintaining a selected voltage between said first and second output terminal means over a range of temperatures when said piezoresistive means is subjected to no, stress, each of said first and second null balance means having an input terminal means and an output terminal means and comprising a first low temperature coefficient of resistivity electrical resistance means in parallel electrical relationship with a high temperature coefficient of resistivity electrical resistance means, said first low temperature coefficient of resistivity electrical resistance means and said high temperature coefficient of resistivity means being together being in series electrical relationship with a second low temperature coefficient of resistivity electrical resistance means between said null balance input means and output means, said first and second null balance input terminal means being electrically connected to on another and being adapted to receive an input voltage of a second polarity, said first null balance means output terminal means being electrically connected to said first piezoelectric means first terminal means and said second null balance means output terminal means being electrically connected to said fourth piezoelectric means second terminal means.

A system for sensing pressure comprising:

• a pressure sensing means comprising first, second, third, and fourth piezoresistive means, each having first and second terminal means and each having a high temperature coefficient of resistivity, said first piezoresistive means second terminal means being electrically connected to said second piezoresistive means first terminal means, said second piezoresistive means second terminal means being electrically connected to said third piezoresistive means first terminal means, and said third piezoresistive means second terminal means being electrically connected to said fourth piezoresistive means first terminal means, said second piezoresistive means second terminal means and third piezoresistive means first terminal means being adapted to receive an input voltage of a first polarity, said first piezoresistive means second terminal means and said second piezoresistive means first terminal means being electrically connected to a first output terminal means, and said third piezoresistive means second terminal means and said fourth piezoresistive means first terminal means being electrically connected to a second output terminal means;
• and
• first and second span compensation means, each of said span compensation means including a low temperature coefficient of resistivity electrical resistor means having first and second terminal means, said first and second span compensation means first terminal means being adapted to be electrically connected to first and second voltage sources, respectively, said first span compensation means second terminal means being e ectrically connected to said second piezoresistive means second terminal means and said third piezoresistive means first terminal means, and said second span compensation means second terminal means being electrically connected to said first piezoresistive means first terminal means and said fourth piezoresistive means first terminal means.

A system for sensing pressure comprising:

• a pressure sensing means comprising first, second, third, and fourth piezoresistive means, each having first and second terminal means and each having a high temperature coefficient of resistivity said first piezoresistive means second terminal means being electrically connected to said second piezoresistive means first terminal means, said second piezoresistive means second terminal means being electrically connected to said third piezoresistive means first terminal means, and said third piezoresistive means second terminal means being electrically connected to said fourth piezoresistive means first terminal means, said second piezoresistive means second terminal means and third piezoresistive means first terminal means being adapted to receive an input voltage of a first polarity, said first piezoresistive means second terminal means and said second piezoresistive means first terminal means being electrically connected to a first output terminal means, and said third piezoresistive means second terminal means and said fourth piezoresistive means first terminal means being electrically connected to a second output terminal means;
• and
• maximum output compensation means including a high temperature coefficient of resistivity electrical resistor means having first and second terminal means, said maximum output compensation means first terminal means being electrically connected to said first output terminal means and said maximum output second terminal means being electrically connected to said second output terminal means.