Current reference operative drive-sense circuit (dsc) with voltage amplifier
A current reference operative drive-sense circuit (DSC) includes a current source operably coupled to a load and a voltage-mode analog to digital converter (ADC). When enabled, the current source is configured to drive a sinusoidal current reference signal to the load thereby generating a load voltage that is based on the sinusoidal current reference signal and an impedance of the load. The voltage-mode ADC is operably coupled the load and to the current source. When enabled, the voltage-mode ADC configured to perform digital sampling of the load voltage and to generate a digital signal that is representative of the load voltage. In some implementations, one or more processing modules is configured to execute operational instructions to process the digital signal that is representative of the load voltage in accordance with determining impedance of the load and/or change of impedance of the load.
1. A current reference operative drive-sense circuit (DSC) comprising:
a current source operably coupled to a load, wherein when enabled, the current source configured to drive a sinusoidal current reference signal to the load thereby generating a load voltage that is based on the sinusoidal current reference signal and an impedance of the load;
a voltage scaler operably coupled the load and to the current source, wherein, when enabled, the voltage scaler configured to scale the load voltage thereby generating a scaled load voltage; and
a voltage-mode analog to digital converter (ADC) operably coupled the voltage scaler, wherein when enabled, the voltage-mode ADC configured to perform digital sampling of the scaled load voltage and to generate a digital signal that is representative of the scaled load voltage.
2. The current reference operative DSC of claim 1 , wherein:
the voltage-mode ADC configured to perform digital sampling within a first range that includes the load voltage; and
the voltage-mode ADC configured to perform digital sampling within a second range that includes the scaled load voltage.
3. The current reference operative DSC of claim 2 , wherein the voltage-mode ADC configured to perform digital sampling within the second range that includes the scaled load voltage in accordance with more efficient operation and accuracy than within the first range that includes the load voltage.
4. The current reference operative DSC of claim 1 , wherein the voltage-mode ADC is a sigma delta ADC.
5. The current reference operative DSC of claim 1 , wherein the load voltage is a product of the sinusoidal current reference signal multiplied by the impedance of the load.
6. The current reference operative DSC of claim 1 further comprising:
memory that stores operational instructions; and
one or more processing modules operably coupled to the voltage-mode ADC and to the memory, wherein, when enabled, the one or more processing modules configured to execute the operational instructions to:
process the digital signal that is representative of the scaled load voltage to determine the scaled load voltage;
determine the load voltage based on the scaled load voltage and a voltage scaler value of the voltage scaler; and
determine the impedance of the load based on the load voltage and the sinusoidal current reference signal.
7. The current reference operative DSC of claim 1 , wherein the load is a liquid crystal display (LCD) capacitive load.
8. The current reference operative DSC of claim 1 , wherein the load is a sensor or an actuator.
9. The current reference operative DSC of claim 1 , wherein the load is a touch screen capacitive load.
10. The current reference operative DSC of claim 9 , wherein user interaction with the touch screen capacitive load causes a change of the impedance of the touch screen capacitive load.
11. The current reference operative DSC of claim 1 , a change of the impedance of the load causes a change of the load voltage.
12. The current reference operative DSC of claim 11 further comprising:
memory that stores operational instructions; and
one or more processing modules operably coupled to the voltage-mode ADC and to the memory, wherein, when enabled, the one or more processing modules configured to execute the operational instructions to:
before the change of the impedance of the load, process the digital signal that is representative of the scaled load voltage to determine a first value of the scaled load voltage;
determine a first load voltage based on the first value of the scaled load voltage and a voltage scaler value of the voltage scaler;
after the change of the impedance of the load, process the digital signal that is representative of the scaled load voltage to determine a second value of the scaled load voltage that is based on the change of the impedance of the load; and
determine a second load voltage based on the second value of the scaled load voltage and the voltage scaler value of the voltage scaler; and
determine the change of the impedance of the load based on the first value of the load voltage, the second value of the load voltage, and the sinusoidal current reference signal.
13. A current reference operative drive-sense circuit (DSC) comprising:
a current source operably coupled to a load, wherein when enabled, the current source configured to drive a sinusoidal current reference signal to the load thereby generating a load voltage that is based on the sinusoidal current reference signal and an impedance of the load;
a voltage amplifier, which includes an operational amplifier with negative feedback, operably coupled the load and to the current source, wherein, when enabled, the voltage amplifier configured to scale the load voltage thereby generating a scaled load voltage; and
a voltage-mode analog to digital converter (ADC) operably coupled the voltage amplifier, wherein when enabled, the voltage-mode ADC configured to perform digital sampling of the scaled load voltage and to generate a digital signal that is representative of the scaled load voltage.
14. The current reference operative DSC of claim 13 , wherein the voltage amplifier, which includes the operational amplifier with negative feedback, includes a first impedance coupled between an output of the operational amplifier and a non-inverting input of the operational amplifier and a second impedance coupled between the non-inverting input of the operational amplifier and ground.
15. The current reference operative DSC of claim 13 , wherein:
the voltage-mode ADC configured to perform digital sampling within a first range that includes the load voltage; and
the voltage-mode ADC configured to perform digital sampling within a second range that includes the scaled load voltage.
16. The current reference operative DSC of claim 15 , wherein the voltage-mode ADC configured to perform digital sampling within the second range that includes the scaled load voltage in accordance with more efficient operation and accuracy than within the first range that includes the load voltage.
17. The current reference operative DSC of claim 13 , wherein the load voltage is a product of the sinusoidal current reference signal multiplied by the impedance of the load.
18. The current reference operative DSC of claim 13 further comprising:
memory that stores operational instructions; and
one or more processing modules operably coupled to the voltage-mode ADC and to the memory, wherein, when enabled, the one or more processing modules configured to execute the operational instructions to:
process the digital signal that is representative of the scaled load voltage to determine the scaled load voltage;
determine the load voltage based on the scaled load voltage and a voltage scaler value of the voltage amplifier; and
determine the impedance of the load based on the load voltage and the sinusoidal current reference signal.
19. The current reference operative DSC of claim 13 , a change of the impedance of the load causes a change of the load voltage.
20. The current reference operative DSC of claim 19 further comprising:
memory that stores operational instructions; and
one or more processing modules operably coupled to the voltage-mode ADC and to the memory, wherein, when enabled, the one or more processing modules configured to execute the operational instructions to:
before the change of the impedance of the load, process the digital signal that is representative of the scaled load voltage to determine a first value of the scaled load voltage;
determine a first load voltage based on the first value of the scaled load voltage and a voltage scaler value of the voltage amplifier;
after the change of the impedance of the load, process the digital signal that is representative of the scaled load voltage to determine a second value of the scaled load voltage that is based on the change of the impedance of the load; and
determine a second load voltage based on the second value of the scaled load voltage and the voltage scaler value of the voltage amplifier; and
determine the change of the impedance of the load based on the first value of the load voltage, the second value of the load voltage, and the sinusoidal current reference signal.