Circuit comprising a capacitive circuit component
View Patent ↗A circuit has a first capacitive circuit component, having a first terminal and a second terminal, and an amplifier, having a first input and an output, the first input coupled to the first terminal and the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal.
1. A circuit, comprising:
a first capacitive circuit component, having a first terminal and a second terminal,
an amplifier, having a first input, a second input, and an output, the first input coupled to the first terminal, the second input to a first reference potential, to amplify a potential difference between a potential of the first input and the first reference potential, and the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal,
a second capacitive circuit component coupled between the first terminal and a second reference potential, and
a resistor having a resistor terminal directly to the first terminal and the second capacitive circuit component.
2. A circuit according to claim 1 , wherein the amplifier has a negative gain.
3. A circuit according to claim 1 , further comprising:
a voltage follower coupled between the first terminal and the first input of the amplifier.
4. A circuit according to claim 1 , further comprising:
a low-pass filter coupled between the output of the amplifier and the second terminal.
5. A circuit according to claim 1 , wherein the first and second reference potentials are equal.
6. A circuit according to claim 1 , further comprising:
an alternating voltage generator, coupled to the first terminal, to generate an alternating potential at the first terminal.
7. A device, comprising:
a first circuit node,
a second circuit node,
a first capacitive circuit component, having a first terminal and a second terminal, the first terminal coupled to the first circuit node and the second terminal coupled to the second circuit node,
an amplifier, having a first input, a second input, and an output, the first input coupled to the first circuit node, the second input coupled to a first reference potential, to amplify potential difference between a potential of the first circuit node and the first reference potential, and the output coupled to the second circuit node, wherein the first circuit node replicates a terminal of an emulated capacitance,
a second capacitive circuit component coupled between the first circuit node and a second reference potential, and
a resistor having a resistor terminal directly coupled to the first circuit node and the second capacitive circuit component.
8. A circuit according to claim 7 , wherein a magnitude of the emulated capacitance depends on a gain of the amplifier.
9. A circuit according to claim 7 , wherein a gain of the amplifier is negative.
10. A circuit according to claim 7 , further comprising:
a voltage follower coupled between the first circuit node and the first input of the amplifier.
11. A circuit according to claim 7 , further comprising:
a low-pass filter coupled between the output of the amplifier and the second circuit node.
12. A device, comprising:
a first circuit node,
a second circuit node,
means for generating a first capacitance between the first circuit node and the second circuit node,
means for generating a potential difference between the first circuit node and the second circuit node to emulate a terminal of an emulated capacitance at the first circuit node,
means for generating a second capacitance between the first circuit node and a reference potential, and
means for providing a resistance directly coupled to the first circuit node and the second capacitance.
13. A circuit according to claim 12 , wherein a value of the emulated capacitance depends on a value of the potential difference.
14. A filter, comprising:
a first capacitive circuit component, having a first terminal and a second terminal,
an amplifier, having an input, a second input, and an output, the input coupled to the first terminal, the second input coupled to a first reference potential, to amplify a potential difference between a potential of the first input and the first reference potential, and the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal,
a second capacitive circuit component coupled between the first terminal and a second reference potential, and
a resistor having a resistor terminal directly coupled to the first terminal and the second capacitive circuit component.
15. A filter according to claim 14 , wherein the first capacitive circuit component generate a pole of a transfer function of the filter.
16. A filter, comprising:
a first circuit node,
a second circuit node,
a first capacitive circuit component, having a first terminal and a second terminal, the first terminal coupled to the first circuit node and the second terminal coupled to the second circuit node,
an amplifier, having an input, a second input, and an output, the input coupled to the first circuit node, the second input coupled to a first reference potential, to amplify a potential difference between a potential of the first circuit node and the first reference potential, and the
output coupled to the second circuit node, wherein the first circuit node replicates a terminal of an emulated capacitance,
a second capacitive circuit component coupled between the first circuit node and a second reference potential, and
a resistor having a resistor terminal directly coupled to the first circuit node and the second capacitive circuit component.
17. A filter according to claim 16 , wherein the first capacitive circuit component generates a pole of a transfer function of the filter.
18. A phase-locked loop device, comprising:
a loop filter, comprising: a first capacitive component, having a first terminal and a second terminal,
an amplifier, having an input, a second input, and an output, the input coupled to the first terminal, the second input coupled to a first reference potential, to amplify potential difference between a potential of the first input and the first reference potential, and the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal,
a second capacitive circuit component coupled between the first terminal and a second reference potential, and
a resistor having a resistor terminal directly coupled to the first terminal and the second capacitive circuit component.
19. A phase-locked loop device according to claim 18 , wherein the amplifier has a negative gain.
20. A phase-locked loop device according to claim 18 ,wherein the first capacitive circuit component generates a pole of a transfer function of the phase-locked loop device.
21. A phase-locked loop device according to claim 18 , wherein the phase-locked loop device is a type 2 phase-locked loop device.
22. A phase-locked loop device, comprising:
a loop filter, comprising:
a first circuit node,
a second circuit node,
a first capacitive circuit component, having a first terminal and a second terminal, the first terminal coupled to the first circuit node and the second terminal coupled to the second circuit node,
an amplifier, having a first input, a second input, and an output, the first input coupled to the first circuit node, the second input coupled to a first reference potential, to amplify a potential difference between a potential of the first circuit node and the first reference potential, and the output coupled to the second circuit node, wherein the first circuit node replicates a terminal of an emulated capacitance,
a second capacitive circuit component coupled between the first circuit node and a second reference potential, and
a resistor having a resistor terminal directly coupled to the first circuit node and the second capacitive circuit component.
23. A phase-locked loop device according to claim 22 , wherein a value of the emulated capacitance depends on a gain of the amplifier.
24. A phase-locked loop device according to claim 22 , wherein the first capacitive circuit component generates a pole of a transfer function of the phase-locked loop device.
25. A phase-locked loop device according to claim 22 , wherein the phase-locked loop device is a type 2 phase-locked loop device.
26. A circuit, comprising:
a first capacitive circuit component including a first terminal and a second terminal,
an amplifier including a first input, a second input, and an output, the first input coupled to the first terminal, the second input coupled to a first reference potential, to amplify a potential difference between a potential of the first input and the first reference potential, and
the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal,
a second capacitive circuit component including a first terminal directly coupled to the first terminal of the first capacitive circuit component and a second terminal coupled to a second reference potential, and
a resistor including a resistor terminal coupled to the first terminal of the first capacitive circuit component.
27. A circuit, comprising:
a first capacitive circuit component including a first terminal and a second terminal,
an amplifier including a first input, a second input, and an output, the first input coupled to the first terminal, the second input coupled to a first reference potential, to amplify a potential difference between a potential of the first input and the first reference potential, and
the output coupled to the second terminal to generate a potential difference between the first terminal and the second terminal,
a second capacitive circuit component coupled between the first terminal of the first capacitive circuit component and a second reference potential, and including a first terminal which is at the same potential as the first terminal of the first capacitive circuit component, and
a resistor including a resistor terminal coupled to the first terminal of the first capacitive circuit component.