Fast, high-resolution, indirect measurement of a physical value
View Patent ↗A measurement method or system for measuring a physical value comprises, during a same clock cycle, forming an input signal, a reference signal and an offset signal, the input signal including a parasitic value and a useful measurement value. A relationship between the input signal where the parasitic value has been cancelled out, and the reference signal is derived. From this relationship, a value relating to the physical value is determined. The input signal, reference signal and offset signal are respectively associated with an input element, a reference element and a parasitic element. All elements have a common driving signal, and the parasitic value is depending on the common driving signal. The fact that different signals are formed during a same measurement cycle, and that these signals are sufficient to obtain the desired physical value, makes the measurement method or system of the present invention faster than prior art measurement methods or systems: only one conversion cycle is needed against two cycles needed for dual slope analog-to-digital conversion.
1. A measurement method for measuring a physical value, comprising
during one clock cycle: forming an input signal, a reference signal and an offset signal, the input signal including a parasitic value and a useful measurement value, the signals being respectively associated with an input element, a reference element and a parasitic element, all these elements being coupled in a same current or voltage path, thus having a common driving signal of a same value, the parasitic value depending on the common driving signal, and deriving a relationship between the input signal, from which the parasitic value has been
cancelled out, and the reference signal, and from this relationship, determining a value relating to the physical value.
2. A measurement method according to claim 1 , wherein the input signal is a first voltage.
3. A measurement method according to claim 2 , wherein the first voltage is obtained from a direct voltage drop over the sensing element.
4. A measurement method according to claim 2 , wherein the reference signal is a second voltage.
5. A measurement method according to claim 2 , wherein the offset signal is a third voltage.
6. A measurement method according to claim 1 , wherein the reference signal is a second voltage.
7. A measurement method according to claim 6 , wherein the second voltage is obtained from a direct voltage drop over the reference element.
8. A measurement method according to claim 6 , wherein the offset signal is a third voltage.
9. A measurement method according to claim 1 , wherein the reference element is a reference resistor.
10. A measurement method according to claim 1 , wherein the offset signal is a third voltage.
11. A measurement method according to claim 10 , wherein the third voltage is obtained from a direct voltage drop over the parasitic element.
12. A measurement method according to claim 1 , wherein the physical value includes any of temperature, a pressure, a light intensity, a position.
13. A measurement method according to claim 1 , wherein the input signal, the reference signal and the offset signal are fed to a digital-to-analog converter with at least a first, a second and a third port.
14. A measurement system for indirect measurement of a physical value, comprising
an analog-to-digital converter with at least a first, a second and a third port, each of the at least three ports being suitable for receiving an input signal from an clement, the analog-to-digital converter being suitable for evaluating the physical value in one measurement cycle,
a sensing element having a pre-defined characteristic parameter related to the physical value to be measured, being coupled to the first port for applying an input signal to said first port,
a reference element being coupled to the second port for applying a reference signal to the second port,
an element corresponding to a parasitic value of the sensing element, being coupled to the third port for applying a parasitic value of the sensing element to the third port, the element, the sensing element and the reference element being coupled in a same current or voltage path, thus having a common driving signal of a same value,
means for deriving a relationship between the input signal, from which the parasitic value of sensing element has been cancelled out, and the reference signal, and
means for deriving, from the relationship, a value relating to the physical value.
15. A measurement system according to claim 14 , wherein the reference element is coupled in series with the sensing element.
16. A measurement system according to claim 15 , wherein the element corresponding to a parasitic value of the sensing element is coupled in series with the sensing element.
17. A measurement system according to claim 14 , wherein the element corresponding to a parasitic value of the sensing element is coupled in series with the sensing element.
18. A measurement system according to claim 14 , wherein the reference element comprises a reference resistor.
19. A measurement system according to claim 14 , wherein the physical value is any of a temperature, a pressure, a light intensity, a position.