Multiple range current measurement system with low power dissipation, fast setting time, and low common mode voltage error
AssigneeAgilent Technologies, Inc.
InventorMichael J. Benes
Life of this patent
Estimating the term…
Abstract
A multi-range measuring circuit for measuring a flow of electrical current between a first node and a second node. A measurement resistor is connected to the first node to develop a voltage having a high range output. A summing node connected in series with the measurement resistor acts as an input to an amplifier for developing a second voltage having a low range output having a higher scale factor than the high range output. If the capacity of the amplifier to maintain the low range as a linear function is exceeded, a bypass circuit bypasses excess current flow to the second node.
Claims20
A multi-range measuring circuit for measuring a flow of electrical current, the circuit comprising:
- an in-line sensor which outputs a first signal proportional to the current and having a first scale factor;
- an amplifier circuit having an input serially connected with the in-line sensor and which outputs a second signal proportional to the current and having a second scale factor greater than the first scale factor;
- and
- a bypass circuit which bypasses a portion of the current around the amplifier circuit at values of the input current where the amplifier circuit is non-linear.
A multi-range measuring circuit for measuring a flow of electrical current between a first node and a second node, the circuit comprising:
- a summing node;
- a resistor which conducts the current from the first node to the summing node;
- a first amplifier having a differential input connected across the resistor, to output a first signal representative of a value of the current and according to a first scale factor;
- an inverting amplifier having an input connected to the summing node;
- a non-inverting amplifier connected to an output of the inverting amplifier to output a second signal;
- a feedback resistor connected between an output of the non-inverting amplifier and the summing node, to regulate the second signal to be proportional to the current and according to a second scale factor;
- a detector which outputs a control signal where the second signal is greater than a first predetermined value or less than a second predetermined value;
- and
- a bypass circuit which bypasses a portion of the current from the summing node to the second node according to the control signal.
A multi-range measuring circuit for measuring a flow of electrical current between a first node and a second node, the circuit comprising:
- a resistor which is connected in series between the first node and a third node and which senses the current flow, to output a first voltage representative of the current and having a first scale factor;
- a bypass circuit which is serially connected with the third node and the second node, the bypass circuit having a non-conductive state and a conductive state according to a control signal;
- an amplifier circuit connected to the third node, to output a second voltage representative of a value of the current and to return the current to the second node, the second output voltage having a second scale factor;
- and
- a detector which outputs the control signal to place the bypass circuit in the conductive state, if the magnitude of the current exceeds a predetermined value.
Dependencies are inferred from the claim text.