CURRENT SOURCE WITH ACTIVE COMMON MODE REJECTION
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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).
5 Citations
17 Claims
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1-10. -10. (canceled)
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11. A current source with active common mode rejection, the current source comprising:
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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. - View Dependent Claims (12, 13, 14, 15)
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- 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.
Specification