Signal conditioning circuit for resistive sensors
First Claim
1. A circuit for measuring an unknown resistance, said circuit comprising:
- a first voltage input terminal and a second voltage input terminal;
a first resistor input terminal and a second resistor input terminal;
a first buffer having an input coupled to said first voltage input terminal and an output coupled to said first resistor input terminal;
a second buffer having an input coupled to said second voltage input terminal and an output coupled to said second resistor input terminal; and
a difference circuit configured to measure a difference in current between the current being supplied to said first resistor input terminal and the current being supplied to said second resistor input terminal, wherein, said difference in current is representative of a difference in resistance between a first resistance coupled to said first resistor input terminal and a second resistance coupled to said second resistor input terminal.
1 Assignment
0 Petitions
Accused Products
Abstract
A circuit is provided that can provide, in a single package, a means to monitor a sensing element which uses a variable resistor. The circuit (also known as a signal conditioning circuit) may contain resistor input terminals to which a reference set resistor and a resistive sensor can be attached. A reference voltage signal can be applied to both terminals. There are also means for sensing the resulting current flowing through both the set resistor and the resistive sensor. The difference of the currents flowing through each element can then be monitored as being indicative of the difference in resistance between the set resistor and the resistive sensor. The current difference signal can be used to generate a voltage difference signal indicative of the difference in resistance between the set resistor and the resistive sensor. The signal conditioning circuit may be used to adjust the temperature of various devices.
-
Citations
35 Claims
-
1. A circuit for measuring an unknown resistance, said circuit comprising:
-
a first voltage input terminal and a second voltage input terminal;
a first resistor input terminal and a second resistor input terminal;
a first buffer having an input coupled to said first voltage input terminal and an output coupled to said first resistor input terminal;
a second buffer having an input coupled to said second voltage input terminal and an output coupled to said second resistor input terminal; and
a difference circuit configured to measure a difference in current between the current being supplied to said first resistor input terminal and the current being supplied to said second resistor input terminal, wherein, said difference in current is representative of a difference in resistance between a first resistance coupled to said first resistor input terminal and a second resistance coupled to said second resistor input terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20)
-
-
16. A method of comparing the resistance of a resistive sensor to a reference resistor with a known resistance, said method comprising:
-
applying a reference signal to said resistive sensor and to said reference resistor to generate a current across said resistive sensor and said reference resistor;
measuring the current flowing across said resistive sensor and across said reference resistor; and
comparing the current flowing across said resistive sensor and the current flowing across said reference resistor;
wherein, said applying, measuring, and comparing steps are performed using a self-contained circuit.
-
-
21. A signal conditioning circuit for determining a resistance of a resistive sensor, said signal conditioning circuit comprising:
-
a first voltage input terminal and a second voltage input terminal;
a first resistor input terminal and a second resistor input terminal; and
a difference circuit configured to measure a difference in current between the current being supplied to said first resistor input terminal and the current being supplied to said second resistor input terminal, wherein, said difference in current is representative of a difference in resistance between a first resistance coupled to said first resistor input terminal and a second resistance coupled to said second resistor input terminal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
-
-
33. A system for measuring the resistance of a thermistor comprising:
-
a reference resistor;
an input voltage source; and
a signal conditioning circuit coupled to said reference resistor, said thermistor, and said input voltage source, wherein said signal conditioning circuit configured to direct a signal from said input voltage source to said reference resistor and to said thermistor; and
said signal conditioning circuit is further configured to measure a difference in current between the current being supplied to said thermistor and the current being supplied to said reference resistor. - View Dependent Claims (34, 35)
-
Specification