Semiconductor physical quantity sensor having filter circuits for blocking electromagnetic wave noise
A semiconductor physical quantity sensor device having a power source terminal for receiving a power source potential, a ground terminal for receiving a ground potential, and an output terminal. The semiconductor physical quantity sensor includes a sensor configured to generate a signal, an amplifier configured to amplify the signal, and to output the amplified signal through the output terminal, a first resistor electrically connected between the power source terminal and the amplifier, a second resistor electrically connected between the output terminal and the ground terminal, and a filter electrically connected between the power source terminal and the sensor, and including a third resistor and a capacitor.
1. A semiconductor physical quantity sensor device, comprising:
a sensor configured to sense a physical quantity to thereby generate an electrical signal, the sensor having a low potential side and a high potential side;
a push-pull amplifier circuit configured to amplify the electrical signal generated by the sensor;
a power source terminal for supplying a power source potential thereby;
a ground terminal for supplying a ground potential thereby;
an output terminal configured to output the electrical signal amplified by the amplifier circuit;
a first power source wiring electrically connecting the power source terminal to the sensor;
a second power source wiring electrically connecting the power source terminal to the amplifier circuit;
a ground wiring electrically connecting the ground terminal to the low potential side of the sensor, and to the amplifier circuit;
an electromagnetic-noise filter circuit electrically connected to the first power source wiring;
a first resistor serially electrically connected to the second power source wiring; and
a second resistor electrically connected between the output terminal and the ground terminal.
2. The semiconductor physical quantity sensor device according to claim 1 , further comprising
a first ground wiring electrically connecting the ground terminal to the sensor;
a second ground wiring electrically connecting the ground terminal to the amplifier circuit;
a third resistor serially electrically connected to the second ground wiring; and
a fourth resistor electrically connected between the power source terminal and the output terminal.
3. The semiconductor physical quantity sensor device according to claim 2 , wherein
the first resistor includes a plurality of first resistor elements connected in series,
the third resistor includes a plurality of second resistor elements connected in series, and
the semiconductor physical quantity sensor device further comprises:
a plurality of first switches connected to the plurality of the first resistor elements, each first switch being connected to both ends of and in parallel with a corresponding one of the first resistor elements;
a plurality of second switches connected to the plurality of the second resistor elements, each second switch being connected to both ends of and in parallel with a corresponding one of the second resistor elements; and
a control circuit controlling ON/OFF of the first switches and the second switches.
4. The semiconductor physical quantity sensor device according to claim 2 , further comprising a fifth resistor connected between the power source terminal and the ground terminal.
5. The semiconductor physical quantity sensor device according to claim 2 , further comprising a sensor chip that has a front surface and a back surface, wherein
the sensor is disposed on the back surface of the sensor chip, and
a pressure is applied as the physical quantity to the sensor chip from a side of the back surface.
6. The semiconductor physical quantity sensor device according to claim 1 , wherein the first resistor has a resistance value set such that output characteristics of the electrical signal amplified by the amplifier circuit cancel non-linearity of output characteristics of the electrical signal generated by the sensor.
7. The semiconductor physical quantity sensor device according to claim 6 , wherein the first resistor has the resistance value set such that a first equation expressing the output characteristics of the electrical signal generated by the sensor and a second equation expressing the output characteristics of the electrical signal amplified by the amplifier circuit are linearly symmetric with respect to an axis defined by a linear equation expressing output characteristics without non-linearity of the electrical signal output from the output terminal.
8. The semiconductor physical quantity sensor device according to claim 1 , further comprising a sensor chip that has a front surface and a back surface, wherein
the sensor is disposed on the front surface of the sensor chip, and
a pressure is applied as the physical quantity to the sensor chip, from a side of the front surface.
9. A semiconductor physical quantity sensor device, comprising:
a sensor configured to sense a physical quantity to thereby generate an electrical signal, the sensor having a low potential side and a high potential side;
a push-pull amplifier circuit configured to amplify the electrical signal generated by the sensor;
a power source terminal for supplying a power source potential thereby;
a ground terminal for supplying a ground potential thereby;
an output terminal configured to output the electrical signal amplified by the push-pull amplifier circuit;
a first ground wiring electrically connecting the ground terminal to the sensor;
a second ground wiring electrically connecting the ground terminal to a low potential side of the push-pull amplifier circuit;
a power source wiring electrically connecting the power source terminal to the high potential side of the sensor and to the amplifier circuit;
an electromagnetic-noise filter circuit electrically connected to the power source wiring;
a first resistor serially electrically connected to the second ground wiring; and
a second resistor electrically connected between the power source terminal and the output terminal.
10. The semiconductor physical quantity sensor device according to claim 9 , wherein the first resistor has a resistance value set such that output characteristics of the electrical signal amplified by the push-pull amplifier circuit cancel non-linearity of output characteristics of the electrical signal generated by the sensor.
11. The semiconductor physical quantity sensor device according to claim 10 , wherein the first resistor has the resistance value set such that a first equation expressing the output characteristics of the electrical signal generated by the sensor and a second equation expressing the output characteristics of the electrical signal amplified by the amplifier circuit are linearly symmetric with respect to an axis defined by a linear equation expressing output characteristics without non-linearity of the electrical signal output from the output terminal.
12. The semiconductor physical quantity sensor device according to claim 9 , further comprising a sensor chip that has a front surface and a back surface, wherein
the sensor is disposed on the back surface of the sensor chip, and
a pressure is applied as the physical quantity to the sensor chip from a side of the back surface.
13. A semiconductor physical quantity sensor device having a power source terminal for receiving a power source potential, a ground terminal for receiving a ground potential, and an output terminal, comprising:
a sensor configured to generate a signal;
an amplifier configured to amplify the signal, and to output the amplified signal through the output terminal;
a first resistor electrically connected between the power source terminal and a high potential side of the amplifier;
a second resistor electrically connected between the output terminal and the ground terminal; and
a filter electrically connected between the power source terminal and the sensor, and comprising a third resistor and a capacitor, the third resistor being different from the first resistor.
14. A semiconductor physical quantity sensor device having a power source terminal for receiving a power source potential, a ground terminal for receiving a ground potential, and an output terminal, comprising:
a sensor configured to generate a signal;
an amplifier configured to amplify the signal, and to output the amplified signal through the output terminal;
a first resistor electrically connected between the ground terminal and a low potential side of the amplifier;
a second resistor electrically connected between the output terminal and the power source terminal; and
a filter electrically connected between the power source terminal and the amplifier, and including a third resistor and a capacitor.