Integrated pressure sensor with remote power source and remote read-out
First Claim
1. An integrated structure pressure sensor system that is powered by induction and read out by induction, said structure including a circuit comprising:
- capacitor means in said circuit and including at least one electrode that is susceptible to induced stress and movement by an external source of pressure;
a transistor in said circuit, including source, drain and gate contacts;
a first inductor in said circuit, connected between said source and drain contacts and arranged to respond to an inductively induced voltage to enable current flow between said source and drain contacts;
a second inductor in said circuit, having a first terminal coupled to said source contact and a second terminal coupled to both said capacitor means and said gate contact, said second inductor arranged to respond to an inductively induced voltage to bias said transistor for conduction;
said capacitor means, first inductor, transistor and second inductor comprising a resonant oscillation circuit;
said system further comprising;
induction means external to said structure for inducing voltages in said first inductor and said second inductor, said voltages causing said circuit to oscillate at a resonant frequency that is dependent on a pressure level exerted on said capacitor means by said external source of pressure; and
sense means, external to said structure and inductively coupled to said circuit, for sensing said resonant frequency as an indication of said pressure level.
1 Assignment
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Accused Products
Abstract
An integrated structure pressure sensor that is powered by induction and read out by induction and includes no integral power source, includes an oscillator circuit that is responsive to pressure variations. The oscillator circuit includes a capacitor having an electrode that is susceptible to induced stress and movement by an external source of pressure. A depletion mode semiconductor is preferably present in the circuit and includes source, drain and gate contacts. A first inductor is coupled between the source and drain contacts and is arranged to respond to an inductively induced voltage to enable current flow between the source and drain contacts. A second inductor in the circuit has a first terminal coupled to the source contact and a second terminal coupled to both the capacitor and the gate contact. The second inductor is arranged to respond to an inductively induced voltage to bias the semi-conductor for conduction. The power induction device is positioned external to the semiconductor structure and induces voltages in the first and second inductors, those voltages causing the circuit to oscillate at a frequency that is dependent upon a pressure level exerted on the capacitor by the external source of pressure. A sense circuit is positioned external to the semiconductor structure and is inductively coupled to the circuit for sensing the frequency of oscillation thereof as an indication of the pressure level.
26 Citations
10 Claims
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1. An integrated structure pressure sensor system that is powered by induction and read out by induction, said structure including a circuit comprising:
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capacitor means in said circuit and including at least one electrode that is susceptible to induced stress and movement by an external source of pressure; a transistor in said circuit, including source, drain and gate contacts; a first inductor in said circuit, connected between said source and drain contacts and arranged to respond to an inductively induced voltage to enable current flow between said source and drain contacts; a second inductor in said circuit, having a first terminal coupled to said source contact and a second terminal coupled to both said capacitor means and said gate contact, said second inductor arranged to respond to an inductively induced voltage to bias said transistor for conduction; said capacitor means, first inductor, transistor and second inductor comprising a resonant oscillation circuit; said system further comprising; induction means external to said structure for inducing voltages in said first inductor and said second inductor, said voltages causing said circuit to oscillate at a resonant frequency that is dependent on a pressure level exerted on said capacitor means by said external source of pressure; and sense means, external to said structure and inductively coupled to said circuit, for sensing said resonant frequency as an indication of said pressure level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification