Inductive respiration sensor

摘要

An inductive respiration sensor (10) comprises an inductive transducer (12) and sensing circuitry. The sensing circuitry comprises a transimpedance amplifier, TIA, (14), the sense input (16) of which is operatively connected to the inductive transducer. The TIA is configured to drive a current from its output (20) into the sense input such that the voltage on the sense input follows the voltage applied to the reference input (18) and to cause a voltage on the output indicative of the current. The TIA comprises a first (34) and a second (30) transistor. The collector or drain and the emitter or source of the first transistor are operatively connected between the sense input and the output of the TIA. The emitter or source of the second transistor is connected to the reference input, the collector or drain of the second transistor is connected to the base or gate of the first transistor, and the base or gate of the second transistor is connected to the sense input.

主权项

1. An inductive respiration sensor, comprising
an inductive transducer configured to produce a variable inductance when subjected to mechanical deformation; a transimpedance amplifier having a reference input, a sense input and an output, said sense input being operatively connected to said inductive transducer, said transimpedance amplifier being configured to drive a current from said output into said sense input such that a voltage on said sense input follows a voltage on said reference input and to cause a voltage on said output indicative of said current; wherein said transimpedance amplifier comprises a first transistor having a first connection, a second connection and a third connection, said first connection being a collector or drain, said second connection being an emitter or source and said third connection being a base or gate, said first and second connections of said first transistor being operatively connected between said sense input and said output; a second transistor having a first connection, a second connection and a third connection, said first connection of said second transistor being a collector or drain, said second connection of said second transistor being an emitter or source and said third connection of said second transistor being a base or gate, said second connection of said second transistor being connected to said reference input, said first connection of said second transistor being connected to the third connection of said first transistor, and the third connection of said second transistor being connected to said sense input.