Supply-noise-rejecting current source
| DWPI Title: Supply-noise-rejecting current source for providing constant current, has operational amplifier whose input is connected to voltage source such that constant current depends upon resistance value and voltage output of voltage source |
| 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: Supply-noise-rejecting current source for providing constant current. |
| Advantage: The feedback loop of the circuit forces the voltage at the resistor and node to be constant for rejecting the current being induced into the drain of transistor through the node or the voltage supply node. The current mirror can increase the 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 (400) has a second transistor (M32) which is configured to feed-back supply noise to a feedback resistor (R11). An operational amplifier (op-amp) (U11) outputs the supply noise to a gate (302) of a first transistor (M31) responsive to the second transistor feeding back the supply noise to the feedback resistor. An operational bandwidth network including a second resistor and a capacitor (C21) connected in series with the second resistor. A first terminal of the operational bandwidth network connected to an output of the op-amp. An operational bandwidth is provided based upon a resistance value of the second resistor and a capacitance value of the capacitor. A second input of the op-amp is connected to a control voltage source connected to a ground reference node (GND). A constant current depends upon a resistance value of the feedback resistor and a voltage output of the control voltage source. |
| Filed: 6/25/2018 |
| Application Number: US16016818A |
| Tech ID: SD 14499.0 |
| 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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