CURRENT SOURCE WITH ACTIVE COMMON MODE REJECTION

• US 20130141057A1
• Filed: 08/30/2011
• Published: 06/06/2013
• Est. Priority Date: 09/03/2010
• Status: Active Grant

• Current Assignee: Ivan Batko
• Original Assignee: Ivan Batko
• Inventors: Batko, Ivan
• Granted Patent: US 9,285,809 B2
• Time in Patent Office: Days
• US Class Current: 323/234
• CPC Class Codes: G05F 1/10 Regulating voltage or current G05F1/02 takes precedence; for electric railways B60M3/02
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: H03F 2200/261 Amplifier which being suitable for instrumentation applications
• CPC Class Codes: H03F 2203/45418 the CMCL comprising a resistor addition circuit
• CPC Class Codes: H03F 2203/45422 the CMCL comprising one or more capacitors not as integrating capacitor, e.g. for stability purposes
• CPC Class Codes: H03F 2203/45424 the CMCL comprising a comparator circuit
• CPC Class Codes: H03F 2203/45441 the CMCL comprising an integrating circuit
• CPC Class Codes: H03F 2203/45511 the feedback circuit [FBC] comprising one or more transistor stages, e.g. cascaded stages of the dif amp, and being coupled between the loading circuit [LC] and the input circuit [IC]
• CPC Class Codes: H03F 2203/45512 the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC
• CPC Class Codes: H03F 3/45475 using IC blocks as the active amplifying circuit
• CPC Class Codes: H03F 3/45937 Measuring at the loading circuit of the differential amplifier

Abstract

A current source with active common mode rejection uses a principle of having a branch for the generation of the required current, to the output (107) of which one end of the load (3) is connected; and a branch of the active compensation circuit (ACC) (200), to the output (203) of which the other end of the load (3) is connected. By means of at least one input (201) of the ACC (200), at least one signal is sensed on the load, and subsequently it is processed so that the result of processing of at least one signal from at least one input (201) preferentially represents the common mode voltage, which corresponds to the pair of voltages at the voltage terminals (1) and (2) of the load (3), or voltage close to the common mode voltage. This result is subsequently processed by the regulating circuits of the ACC (200), which compare it to the reference potential value (4), and using the negative feedback principle, set such voltage on the output (203), which, within the control accuracy, leads to the equivalence of the reference potential (4) and the potential corresponding to the result of processing of at least one signal from at least one input (201).

Claims

1-10. -10. (canceled)

11. A current source with active common mode rejection, the current source comprising:

a voltage controlled current control unit;

an active compensation circuit;

a load connected between the voltage controlled current unit and the active compensation circuit,

wherein the current control unit has feedback sensing inputs and for sensing generated current by means of sensing voltage at a reference impedance or voltage at the load, the active compensation circuit has an input for sensing a voltage terminal of the load, a reference potential input for sensing reference potential and an output for the connection of one end of the load, while the active compensation circuit has a circuit configuration with a negative feedback for setting voltage on the output to the value resulting in the equivalence of the reference potential applied to the input and potential preferentially representing common mode voltage of signals applied to the inputs or voltage close to common mode voltage of signals applied to the inputs that is derived from a voltage terminal of the load and applied to at an input of the active compensation circuit.

12. A current source with active common mode rejection according to claim 11 wherein the active compensation circuit has an input unit for the conversion of input signal from an input to signal preferentially representing common mode voltage of signals applied to the inputs or to voltage close to common mode voltage of signals applied to the inputs, applied to an output of the input unit, a differential element to determine deviations of the potential on an output of the input unit from reference potential, a reference potential input for sensing reference potential and a regulating element for sensing the output of the differential element and for setting potential on an output of the active compensation circuit to the value corresponding to the zero output from the differential element, while inputs of the active compensation circuit are connected to the inputs of the input unit, the output of the input unit and the reference input of the active compensation circuit are connected to the inputs of the differential element, the output of the differential element is connected to the input of the regulating element, the output of the regulating element is connected to the output of the active compensation circuit, while the regulating element is of proportional-integral-derivative type or proportional-integral type, or of integral type.

13. A current source with active common mode rejection according to claim 12 wherein an input unit has a voltage follower or voltage amplifier to follow or amplify signal/signals from an input of an active compensation circuit, while an input of the active compensation circuit is applied to the input of the voltage follower or amplifier and the output of the voltage follower or amplifier is interconnected through an impedance with an output of the input unit.

14. A current source with active common mode rejection according to claim 13 wherein a differential element and a regulating element is represented by an operational amplifier in a connection of a summing integrator, the time constant of which is determined by a capacitor connected between an inverting input and an output of the operational amplifier and impedances connected to an output of an input unit, which is connected to the inverting input of the operational amplifier, while a non-inverting input of the operational amplifier is connected to an input of a reference potential and an output of the operational amplifier is connected to an output of an active compensation circuit.

15. A current source with active common mode rejection according to claim 11 wherein an output element for the voltage and/or current amplification front-ends an output of an active compensation circuit.

16. A current source with active common mode rejection for generation of alternating currents wherein a load is connected between a voltage controlled current control unit for provision of current to the load and an active compensation circuit for setting the potential level of the load, connected by means of an output to the load, while an input of the active compensation circuit is used to sense a signal from the load, subsequently a signal from an input by means of an input unit of the active compensation circuit is converted to the common mode voltage corresponding to voltages at the voltage terminals and of the load or to the voltage close to the common mode voltage corresponding to voltages at the voltage terminals and of the load and which is applied to an output of the input unit, subsequently by means of a phase-sensitive detector the difference between potential on an output of the input unit and a reference potential is measured, while voltage directly proportional to the alternating current flowing through the load or voltage representing frequency and phase of the alternating current flowing through the load serves as a reference signal for the phase-sensitive detection, and it is applied to a reference input of the active compensation circuit, while the reference input is interconnected with the reference input of the phase-sensitive detector, signal from the output of the phase-sensitive detector is applied to the input of a regulating element by means of its output signal applied to a control input of a variable gain amplifier and where the voltage directly proportional to the alternating current flowing through the load is applied to the input of the variable gain amplifier, while the branch comprising the input unit, the phase-sensitive detector, the regulating element and the variable gain amplifier has a negative feedback circuit configuration for setting the zero value signal on the output of the phase-sensitive detector.

17. A current source with active common mode rejection according to claim 16 wherein an input of a variable gain amplifier is interconnected with a reference input of an active compensation circuit, to which voltage directly proportional to alternating current flowing through a load is applied.