Supply-noise-rejecting current source
| DWPI Title: Current source for outputting constant current, in which operational bandwidth is based upon resistance value of second resistor and capacitance value of capacitor |
| Abstract: Various technologies pertaining to a high-impedance current source are described herein. The current source outputs a substantially constant current by way of a first transistor that draws current from a supply. The current source is configured to feed back noise from the supply to a feedback resistor at an input of an operational amplifier (op-amp) by way of a second transistor. The feedback resistor and the op-amp are configured such that responsive to receiving the supply noise feedback, the op-amp drives a gate voltage of the first transistor to cause the first transistor to reject the supply noise and cause the output of the current source to remain substantially constant. |
| Use: Current source for outputting constant current. |
| Advantage: The current source is configured to feed back noise from the supply to a feedback resistor at an input of an op-amp by way of a second transistor. The current mirror increases an output impedance of the current source at the output terminal of the current source by feeding back stimulation received at the output terminal to the feedback resistor connected to the first input of the op-amp. |
| Novelty: The current source has an operational amplifier (op-amp), a feedback resistor connected to an input of the op-amp and a ground reference node, a first transistor that sources current from a supply. A source (112,120) or a drain (110,118) of the first transistor is an output terminal (116) of the current source. A second transistor is configured to feed-back supply noise to the feedback resistor. The op-amp outputs the supply noise to a gate (114,122) of the first transistor responsive to the second transistor feeding back the supply noise to the feedback resistor. A second resistor is connected to the output of the op-amp. A capacitor is connected to the second resistor and the ground reference node. An operational bandwidth of the current source is based upon a resistance value of the second resistor and a capacitance value of the capacitor. |
| Filed: 7/26/2017 |
| Application Number: US15660296A |
| Tech ID: SD 14208.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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