Diaphragm vacuum gauge with decreased parasitic capacitance

A diaphragm vacuum gauge, comprising:

• a sensor chip including a first electrode provided on a base, a second electrode provided on a diaphragm so as to face the first electrode, the diaphragm and the base being disposed with a gap therebetween, a third electrode provided outside the first electrode on the base, and a fourth electrode provided outside the second electrode on the diaphragm so as to face the third electrode, and configured such that a distance between the first electrode and the second electrode changes in accordance with displacement of the diaphragm caused by pressure of a measurement target medium;
• a first operational amplifier configured to convert a current output from the first electrode to a voltage and amplify the voltage;
• a second operational amplifier configured to convert a current output from the third electrode to a voltage and amplify the voltage;
• a first coaxial cable configured to connect the first electrode and the first operational amplifier with each other;
• and
• a second coaxial cable configured to connect the third electrode and the second operational amplifier with each other, wherein
• the first electrode is connected to a virtual ground of the first operational amplifier by a core wire of the first coaxial cable, and the third electrode is connected to a virtual ground of the second operational amplifier by a core wire of the second coaxial cable.