Physical quantity detecting device

1. A physical quantity detecting device comprising:

a physical quantity detecting sensor configured to detect a physical quantity of a measurement target fluid and output a detection signal;

a compensation amount calculation circuit configured to calculate, by using the detection signal, a lead compensation amount used in lead compensation for the detection signal; and

a gain control circuit configured to adjust the lead compensation amount based on a deviation that is an amount of change in lead compensation amount over time,

wherein the physical quantity detecting sensor, the compensation amount calculation circuit, and the gain control circuit are mounted on the same board formed of a glass epoxy resin.

2. The physical quantity detecting device according to claim 1 , wherein the gain control circuit is configured to set the lead compensation amount to zero when the deviation is equal to or more than a predetermined value.

3. The physical quantity detecting device according to claim 1 , wherein the deviation uses a moving average of the lead compensation amount.

4. The physical quantity detecting device according to claim 1 , wherein the gain control circuit is configured to adjust the lead compensation amount by using a result of determining a state of the physical quantity detecting sensor by using the detection signal.

5. The physical quantity detecting device according to claim 4 , further comprising a noise attenuation processing circuit configured to reduce output noise of the physical quantity detecting sensor,

wherein the state of the physical quantity detecting sensor is determined based on an amount of delay that occurs due to the noise attenuation processing circuit, and the lead compensation amount.

6. The physical quantity detecting device according to claim 5 , wherein the determination based on the lead compensation amount is determination of a magnitude relationship between the lead compensation amount and a threshold value having a hysteresis characteristic.

7. The physical quantity detecting device according to claim 5 , further comprising:

a storage configured to store, as a signal at a time of state change, the detection signal when the state of the physical quantity detecting sensor is changed; and

a first gain coefficient calculation circuit configured to determine a first gain used by the gain control circuit according to a difference between a latest detection signal and the signal at the time of the state change.

8. The physical quantity detecting device according to claim 5 , further comprising a second gain coefficient calculation circuit configured to determine a second gain used by the gain control circuit according to a time elapsed from a time when the state of the physical quantity detecting sensor is changed.

9. The physical quantity detecting device according to claim 1 , wherein the compensation amount calculation circuit is configured to set a different gain for each of a case where the detection signal increases and a case where the detection signal decreases.

10. The physical quantity detecting device according to claim 1 , further comprising a flow rate sensor configured to detect a flow rate of the measurement target fluid,

wherein the physical quantity is a temperature, and the compensation amount calculation circuit is configured to change a gain used to calculate the lead compensation amount based on an output of the flow rate sensor.

11. The physical quantity detecting device according to claim 10 , wherein a temperature characteristic of the flow rate sensor is corrected by using a temperature of the flow rate sensor corrected using the lead compensation amount adjusted by the gain control circuit.