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Method to find a value within a range using weighted subranges

Imported: 23 Feb '17 | Published: 22 Oct '02

William N. Thompson, John D. Porter, Larren Gene Weber

USPTO - Utility Patents

Abstract

A method of finding an unknown value from within a range of values is disclosed that divides the range into weighted subranges and then, beginning with an arbitrary search value within the range, performs a number of simple comparisons to determine the value for each subrange that will result in a match with the target value. This method can also detect those cases where the target value lies outside the range. In one embodiment, the method of finding an unknown value within a range of values is applied to impedance matching. In this embodiment, the output impedance of a pin on an integrated circuit is automatically matched to the impedance of the load connected to it. The output driver has a controllable impedance that can be adjusted within a specific range of impedances to match the external load impedance it is to drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of the general operation of the method of finding a value within range using weighted subranges.

FIG. 1A is a block diagram of one embodiment of an impedance matching system including a controllable impedance.

FIG. 1B is a block diagram of one embodiment of an impedance matching system including a variable impedance and a control system.

FIG. 2A is a diagram of a metal-oxide-semiconductor field-effect transistor (MOSFET) suitable for use in connection with one embodiment of the present invention.

FIG. 2B is a graph of the drain-to-source conductance of a MOSFET suitable for use as a variable impedance in one embodiment of the present invention.

FIG. 2C is a schematic diagram of a parallel connection of serially connected resistor-transistor pairs suitable for use in connection with one embodiment of the present invention.

FIG. 3 is a block diagram of a control system for use in connection with one embodiment of the present invention.

FIG. 4A is part one of a flow chart of one embodiment of an impedance matching method.

FIG. 4B is part two of a flow chart of one embodiment of an impedance matching method.

Claims

1. An impedance matching circuit, comprising:

2. An impedance matching circuit, comprising:

3. The impedance matching circuit of claim 2, wherein the controllable impedance includes a circuit connected to the second signal line for sensing the characteristic impedance looking into the second signal line and for adjusting the controllable impedance in response thereto.

4. An impedance matching circuit, comprising:

5. A dynamic impedance matching circuit, comprising:

6. An impedance matching system for an external pin on a integrated circuit, comprising:

7. An impedance matching circuit, comprising:

8. The impedance matching circuit of claim 7, wherein the controllable impedance includes a circuit connected to the second signal line for sensing the characteristic impedance looking into the second signal line and for adjusting the controllable impedance in response thereto.

9. An impedance matching circuit, comprising:

10. A dynamic impedance matching circuit, comprising:

11. An impedance matching system for an external pin on a integrated circuit, comprising:

12. An impedance matching circuit, comprising:

13. The impedance matching circuit of claim 12, wherein the controllable impedance includes a circuit connected to the second signal line for sensing the characteristic impedance looking into the second signal line and for adjusting the controllable impedance in response thereto.

14. An impedance matching circuit, comprising:

15. A dynamic impedance matching circuit, comprising:

16. An impedance matching system for an external pin or a integrated circuit, comprising:

17. An impedance matching circuit, comprising:

18. The impedance matching circuit of claim 17, wherein the controllable impedance includes a circuit connected to the second signal line for sensing the characteristic impedance looking into the second signal line and for adjusting the controllable impedance in response thereto.

19. An impedance matching circuit, comprising:

20. A dynamic impedance matching circuit, comprising:

21. An impedance matching system for an external pin on a integrated circuit, comprising:

22. The impedance matching system of claim 21, wherein the state machine is operable for generating count up and count down signals.

23. A dynamic impedance matching circuit, comprising:

24. The dynamic impedance matching circuit of claim 23, wherein the state machine is operable for generating count up and count down signals.