Noise cancellation circuit

1 . An apparatus, comprising:

a load circuit configured to draw a first current;

a sense resistor configured to provide a voltage based on the first current; and

a current compensation circuit configured to generate a second current based on the voltage, wherein the second current is drawn away from the load circuit, and wherein the current compensation circuit comprises an amplifier circuit having a first input connected to a first terminal of the sense resistor and a second input connected to a second terminal of the sense resistor.

2 . The apparatus of claim 1 , further comprising:

a mid-frequency noise suppression filter circuit electrically connected to a circuit node between the sense resistor and the load circuit; and

a high-frequency noise suppression filter circuit electrically connected to the circuit node.

3 . The apparatus of claim 2 , wherein the mid-frequency noise suppression filter circuit comprises:

a transconductance circuit; and

a capacitor electrically connected to the transconductance circuit in a parallel arrangement.

4 . The apparatus of claim 2 , wherein the high-frequency noise suppression filter circuit comprises a decoupling capacitor.

5 . The apparatus of claim 1 , wherein the current compensation circuit further comprises:

a voltage reference generator electrically connected to the first terminal of the sense resistor and to the first input of the amplifier circuit;

a transistor with a gate terminal electrically connected to an output of the amplifier circuit and a source/drain terminal electrically connected to the second terminal of the sense resistor.

6 . The apparatus of claim 5 , wherein the voltage reference generator comprises:

a reference resistor; and

an adjustable current source electrically connected to the reference resistor and configured to generate a reference current.

7 . The apparatus of claim 1 , wherein the current compensation circuit further comprises a voltage reference generator electrically connected to the first terminal of the sense resistor and to the first input of the amplifier circuit.

8 . The apparatus of claim 1 , wherein the current compensation circuit further comprises a transistor with a gate terminal electrically connected to an output of the amplifier circuit and a source/drain terminal electrically connected to the second terminal of the sense resistor.

9 . The apparatus of claim 1 , further comprising a noise suppression filter circuit electrically connect to the sense resistor.

10 . A system, comprising:

a power distribution network configured to provide a supply voltage;

a circuit electrically connected to the power distribution network and configured to receive the supply voltage; and

a noise cancellation circuit between the power distribution network and the circuit, wherein the noise cancellation circuit is configured to generate a compensation current drawn away from the power distribution network by the circuit, wherein the noise cancellation circuit comprises:

a sense resistor comprising a first terminal and a second terminal; and

an amplifier circuit comprising a first input connected to the first terminal of the sense resistor and a second input connected to the second input of the sense resistor.

11 . The system of claim 10 , wherein the noise cancellation circuit is further configured to suppress noise over a first frequency range.

12 . The system of claim 11 , further comprising:

a mid-frequency noise suppression filter circuit configured to suppress noise over a second frequency range lower than the first frequency range; and

a high-frequency noise suppression filter circuit configured to suppress noise over a third frequency range higher than the second frequency range.

13 . The system of claim 12 , wherein the noise cancellation circuit and the high-frequency noise suppression filter circuits are configured to operate with noise suppression levels higher than that of the mid-frequency noise suppression filter circuit.

14 . The system of claim 10 , wherein the transconductance circuit noise cancellation circuit further comprises:

a voltage reference generator

electrically connected to the amplifier circuit and to the sense resistor; and

a transistor electrically connected to the amplifier circuit and to the sense resistor.

15 . The system of claim 14 , wherein the voltage reference generator comprises:

a reference resistor; and

an adjustable current source electrically connected to the reference resistor.

16 . A method, comprising:

drawing, with a load circuit, a load current from a power distribution network;

providing a voltage based on the load current flowing through a sense resistor;

generating a compensation current based on the voltage being received by a current compensation circuit that comprises an amplifier circuit having a first input connected to a first terminal of the sense resistor and a second input connected to a second terminal of the sense resistor; and

setting a current level of the power distribution network substantially equal to a summation of the load current and the compensation current.

17 . The method of claim 16 , further comprising:

suppressing a noise at a first noise suppression level for a first frequency range;

suppressing the noise at a second noise suppression level for a second frequency range lower than the first frequency range; and

suppressing the noise at a third noise suppression level for a third frequency range higher than the second frequency range, wherein the first and third noise suppression levels are higher than the second noise suppression level.

18 . The method of claim 16 , wherein generating the compensation current comprises controlling a gate terminal of a transistor based on an output of the amplifier circuit.

19 . The method of claim 16 , wherein generating the compensation current comprises calibrating a bleed current in a noise cancellation circuit.

20 . The method of claim 19 , wherein generating the bleed current comprises:

setting the load circuit to a peak current;

setting an adjustable current source to a first current;

measuring one or more voltages in the noise cancellation circuit at the first current;

setting the adjustable current source to a second current;

measuring one or more voltages in the noise cancellation circuit at the second current; and

setting an operating current of the adjustable current source based on the one more voltages measurements from the noise cancellation circuit.