Blocking a leakage current
View Patent ↗An apparatus includes an oscillator circuit that includes terminals to couple a second circuit having an impedance to the oscillator circuit. The apparatus includes a third circuit that is coupled to at least one of the terminals to isolate a leakage current from at least part of the oscillator circuit.
1. An apparatus comprising:
an oscillator circuit comprising terminals to couple a second circuit having an impedance to the oscillator circuit; and
a filter coupled at least one of the terminals to isolate a leakage current from at least part of the oscillator circuit.
2. The apparatus of claim 1 , wherein the oscillator circuit comprises an amplifier, and the filter isolates the amplifier from the leakage current.
3. The apparatus of claim 2 , wherein the amplifier comprises a feedback impedance, and the filter isolates the feedback impedance from the leakage current.
4. The apparatus of claim 2 , wherein the terminals are coupled to an input terminal of the amplifier and an output terminal of the amplifier.
5. The apparatus of claim 1 , wherein the second circuit comprises a crystal.
6. The apparatus of claim 1 , wherein the oscillator circuit comprises:
an amplifier; and
capacitors coupled to the amplifier to form a resonant tank with the impedance.
7. The apparatus of claim 1 , further comprising:
an electrostatic discharge protection circuit coupled to at least one of the terminals and capable of generating the leakage current.
8. The apparatus of claim 7 , wherein the oscillator circuit, electrostatic discharge protection circuit and the filter are part of a semiconductor package, and the second circuit is external to the semiconductor package.
9. The apparatus of claim 1 , wherein the filter comprises a high pass filter.
10. The apparatus of claim 1 , further comprising a voltage reference circuit to bias a terminal of the filter.
11. The apparatus of claim 10 , wherein the voltage reference circuit comprises a transistor divider circuit that comprises:
at least one n-channel metal-oxide-semiconductor field-effect-transistor coupled between the terminal of the high pass filter and a first voltage supply terminal; and
at least one p-channel metal-oxide-semiconductor field-effect-transistor coupled between the terminal of the high pass filter and a second voltage supply terminal.
12. A method comprising:
coupling an electrostatic discharge protection circuit to an oscillator; and
isolating leakage current generated by the electrostatic discharge protection circuit from at least part of the oscillator during a state of the oscillator in which said at least part of the oscillator communicates an oscillating signal.
13. The method of claim 12 , wherein the isolating comprises:
isolating an amplifier of the oscillator from the leakage current.
14. The method of claim 12 , wherein the isolating further comprises:
isolating a feedback impedance of the amplifier from the leakage current.
15. The method of claim 14 , further comprising:
coupling the feedback impedance between an input terminal of the amplifier and an output terminal of the amplifier.
16. The method of claim 12 , further comprising:
coupling an impedance to the electrostatic discharge protection circuit and to the oscillator.
17. The method of claim 16 , wherein the impedance comprises a crystal.
18. A system comprising:
an oscillator circuit to provide a reference signal, the oscillator circuit comprising terminals to couple a second circuit having an impedance to the oscillator circuit;
an electrostatic discharge protection circuit coupled to one of the terminals and capable of generating a leakage current;
a fourth circuit to isolate the leakage current from at least part of the oscillator circuit while the oscillator circuit provides the reference signal; and
a radio frequency circuit to receive the reference signal.
19. The system of claim 18 , wherein the oscillator circuit comprises an amplifier, and the fourth circuit isolates the amplifier from the leakage current.
20. The system of claim 19 , wherein the amplifier comprises a feedback impedance, and the fourth circuit isolates the feedback impedance from the leakage current.
21. The system of claim 19 , wherein the terminals are coupled to an input terminal of the amplifier and an output terminal of the amplifier.
22. The system of claim 18 , wherein the second circuit comprises a crystal.
23. The system of claim 18 , wherein the oscillator circuit comprises:
an amplifier; and
capacitors coupled to the amplifier to form a resonant tank with the second circuit.
24. The system of claim 18 , wherein the radio frequency circuit comprises a transceiver.
25. The system of claim 18 , wherein the oscillator circuit, electrostatic discharge protection circuit and fourth circuit are part of a semiconductor package, and the second circuit is external to the semiconductor package.
26. The system of claim 18 , wherein the fourth circuit comprises a filter to isolate the leakage current.
27. An apparatus comprising:
a die comprising oscillator circuitry; and
a filter to isolate leakage current from at least part of the oscillator circuitry.
28. The apparatus of claim 27 , wherein the circuit is fabricated on the die.
29. The apparatus of claim 27 , wherein the circuit isolates an amplifier of the oscillator circuitry from the leakage current.
30. The apparatus of claim 27 , wherein the circuit isolates a feedback resistor of the amplifier from the leakage current.
31. The apparatus of claim 27 , wherein at least some of the leakage current originates with a source external to the die.
32. An apparatus comprising:
an oscillator circuit comprising terminals to couple a second circuit having an impedance to the oscillator circuit;
a high pass filter coupled to at least one of the terminals to isolate a leakage current from at least part of the oscillator circuit; and
a voltage reference circuit to bias a terminal of the high pass filter.
33. The apparatus of claim 32 , further comprising:
an electrostatic discharge protection circuit coupled to at least one of the terminals and capable of generating the leakage current.
34. The apparatus of claim 32 , wherein the voltage reference circuit comprises a transistor divider circuit.
35. A method comprising:
coupling an electrostatic discharge protection circuit to an oscillator;
isolating leakage current generated by the electrostatic discharge protection circuit from at least part of the oscillator, comprising isolating a first node of the oscillator from a second node of the oscillator;
coupling an impedance to the first node;
coupling the electrostatic discharge protection circuit to the first node; and
regulating a voltage of the first node.
36. The method of claim 35 , wherein the isolating comprises at least one of isolating an amplifier of the oscillator from the leakage current and isolating a feedback impedance of the amplifier from the leakage current.
37. A system comprising:
an oscillator circuit to provide a reference signal, the oscillator circuit comprising terminals to couple a second circuit having an impedance to the oscillator circuit;
an electrostatic discharge protection circuit coupled to one of the terminals and capable of generating a leakage current;
a high pass filter to isolate the leakage current from at least part of the oscillator circuit;
a radio frequency circuit to receive the reference signal; and
a voltage reference circuit to bias a terminal of the high pass filter.