Semiconductor apparatus with an analog-to-digital converter and amplifier

1. A semiconductor apparatus, comprising:

an amplifying unit configured to amplify an input signal to output an amplified signal;

a bias controlling unit configured to generate a bias voltage to be applied to said input signal;

an analog-to-digital converting unit configured to analog-to-digital convert said amplified signal into an output signal; and

a controlling unit configured to output a control signal to said bias controlling unit,

wherein said controlling unit outputs said control signal when an output value indicated by said output signal is equal to a predetermined value, and

said bias controlling unit changes said bias voltage in response to said control signal,

wherein said bias controlling unit discretely changes said bias voltage in response to said control signal,

said apparatus further comprising a memory configured to store a table including correction data for said output value,

wherein said bias controlling unit stores said correction data for said output value before and after said bias voltage is discretely changed.

2. The semiconductor apparatus according to claim 1 , wherein said controlling unit calculates a corrected output value corresponding to said changed bias voltage based on said correction data and said output value.

3. The semiconductor apparatus according to claim 1 , wherein said predetermined value is one of a maximum value and a minimum value of a conversion range of a bit number of said analog-to-digital converting unit.

4. The semiconductor apparatus according to claim 3 , wherein said controlling unit outputs said control signal for decreasing said bias voltage when said output value coincides with said maximum value, and outputs control signal for increasing said bias voltage when said output value coincides with said minimum value.

5. The semiconductor apparatus according to claim 1 , wherein said bias voltage is supplied to one of an inverting input terminal and a non-inverting input terminal of an operational amplifier of said amplifying unit.

6. A data transmitting apparatus, comprising:

a sensor; and

a semiconductor apparatus configured to generate a digital data based on a sensor signal outputted from said sensor,

wherein said semiconductor apparatus includes:

an amplifying circuit configured to include an amplifying unit and a bias controlling unit, said amplifying unit amplifies said sensor signal to output an amplified signal, and said bias controlling unit generates a bias voltage to be applied to said sensor signal,

an analog-to-digital converting circuit configured to analog-to-digital convert said amplified signal into an output signal; and

a micro computer configured to output a control signal to said bias controlling unit based on an analog-to-digital conversion value indicated by said output signal,

wherein said micro computer outputs said control signal when said analog-to-digital conversion value is equal to a predetermined value, and

said bias controlling unit changes said bias voltage in response to said control signal, and

said apparatus further comprising a memory configured to store correction data for correcting analog-to-digital conversion values,

wherein said amplifying circuit supplies a corrected amplified signal corresponding to said bias voltage changed in response to said control signal to said analog-to-digital converting circuit,

said analog-to-digital converting circuit generates a corrected analog-to-digital conversion value by analog-to-digital converting said corrected amplified signal, and supplies said corrected analog-to-digital conversion value to said micro computer, and

said micro computer reads a correction data corresponding to said changed bias voltage from said memory in response to said corrected analog-to-digital conversion value, and calculates a real analog-to-digital conversion value based on said read correction data and said corrected analog-to-digital conversion value.

7. The data transmitting apparatus according to claim 6 , wherein said micro computer outputs said control signal when said analog-to-digital conversion value is one of a maximum value and a minimum value of a conversion range of said analog-to-digital converting circuit, and

said bias controlling unit changes said bias voltage such that said amplified signal is in an input range of said analog-to-digital converting circuit in response to said control signal.

8. A computer program product embodied on a computer-readable medium to operate a data transmitting apparatus used in a tire pressure monitoring system and provided inside a tire, and comprising code that, when executed, causes a computer to perform the following:

controlling a bias controlling unit to generate a bias voltage to be applied to an input signal of an amplifying unit;

controlling an analog-to-digital converting unit to analog-to-digital convert an amplified signal outputted from said amplifying unit into an output signal indicating an analog-to-digital conversion value;

controlling said bias controlling unit to change said bias voltage when said analog-to-digital conversion value is equal to a predetermined value, wherein said controlling said bias controlling unit to change said bias voltage comprises controlling said bias controlling unit to discretely change said bias voltage when said analog-to-digital conversion value is equal to said predetermined value; and

storing correction data for said analog-to-digital conversion values in a memory before and after said bias voltage is changed.

9. The computer program product according to claim 8 , further comprising:

calculating a corrected analog-to-digital conversion value corresponding to said changed bias voltage based on said correction data and said analog-to-digital conversion value.

10. The computer program product according to claim 8 , wherein said predetermined value is one of a maximum value and a minimum value of a conversion range of a bit number of said analog-to-digital converting unit.

11. The computer program product according to claim 10 , wherein said controlling said bias controlling unit to change said bias voltage comprises controlling said bias controlling unit to decrease said bias voltage when said output value coincides with said maximum value, and to increase said bias voltage when said output value coincides with said minimum value.

12. A method for changing a conversion range of an analog-to-digital converting circuit, said method comprising:

generating a bias voltage to be applied to an input signal of an amplifying unit;

analog-to-digital converting an amplified signal outputted from said amplifying unit into an output signal indicating an analog-to-digital conversion value;

changing said bias voltage when said analog-to-digital conversion value is equal to a predetermined value, wherein said changing said bias voltage comprises discretely changing said bias voltage when said analog-to-digital conversion value is equal to said predetermined value;

storing correction data for said analog-to-digital conversion values in a memory before and after said bias voltage is discretely changed; and

calculating a corrected analog-to-digital conversion value corresponding to said changed bias voltage based on said correction data and said analog-to-digital conversion value.

13. The method for changing a conversion range according to claim 12 , wherein said predetermined value is one of a maximum value and a minimum value of a conversion range of a bit number of said analog-to-digital converting unit.

14. The method for changing a conversion range according to claim 13 , wherein said changing said bias voltage comprises controlling said bias controlling unit to decrease said bias voltage when said output value coincides with said maximum value, and to increase said bias voltage when said output value coincides with said minimum value.