Enhanced linearity, low switching perturbation resistor strings

• US 20040189438A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Govindarajulu, Srikanth, Nicholson, Richard, Churchill, Simon
• Granted Patent: US 6,911,896 B2
• Time in Patent Office: Days
• US Class Current: 338/320
• CPC Class Codes: H03M 1/0678 using additional components or elements, e.g. dummy components
• CPC Class Codes: H03M 1/36 simultaneously only, i.e. parallel type
• CPC Class Codes: H03M 1/76 using switching tree

Abstract

A resistor string that may have two resistor matrices laid out back-to-back with selected or all nominally equipotential nodes of the two matrices being interconnected. In certain applications, the matrix may have switch connections at each node, with the second matrix being an inactive matrix that may have the same number or different number, typically fewer resistors than the first matrix. In another embodiment, separate matrices may be used, and the inactive matrix may be smaller and have fewer resistors of a lower value to minimize the effect of gradients across the substrate. Preferred matrices and node connection switch configurations, as well as various embodiments of these and other features of the invention are disclosed.

Claims

1. A resistor string comprising:

a first matrix of N resistors connected in series;

a second matrix of M resistors connected in series;

a first lead connected to a first end of the first matrix and to a first end of the second matrix;

a second lead connected to a second end of the first matrix and to a second end of the second matrix;

at least one node between resistors in the first matrix being connected to a nominally equipotential node between resistors in the second matrix.

2. The resistor string of claim 1 wherein a plurality of nodes between resistors in the first matrix are each connected to nominally equipotential nodes between resistors in the second matrix.

3. The resistor string of claim 2 wherein M=N.

4. The resistor string of claim 2 wherein M is less than N.

5. The resistor string of claim 2 wherein each matrix comprises a matrix having a plurality of rows and columns of resistors.

6. The resistor string of claim 5 wherein the resistors in each matrix are electrically connected so that any two electrically connected rows of resistors in a matrix run in opposite directions across the matrix when traced from the first lead to the second lead.

7. The resistor string of claim 6 wherein the first and second matrices have the same number of rows of resistors, and wherein the rows of the first and second matrices are physically interleaved.

8. The resistor string of claim 7 wherein the current flow in each row of the first matrix, starting from the first lead, is in a different direction across the matrix than the current flow in the respective row of the second matrix, starting from the first lead.

9. The resistor string of claim 8 wherein there is an even number of rows of resistors in each matrix.

10. The resistor string of claim 9 wherein in each matrix, the electrical order of the rows is the same as the physical order of the rows, thereby forming a snake configuration.

11. The resistor string of claim 10 wherein the number of resistors in the second matrix is less than the number of resistors in the first matrix.

12. The resistor string of claim 11 wherein the resistance of the first and second matrix is the same.

13. The resistor string of claim 11 wherein the resistance of the second matrix is less than the resistance of the first matrix.

14. The resistor string of claim 10 wherein, in one of the matrices, the two center rows of resistors are physically adjacent each other without a row of resistors of the other matrix there between.

15. The resistor string of claim 9 wherein for each matrix, given a physical order of rows of 1, 2, . . . N numbering from the first lead, the first half and the second half of the electrical order of physical rows each alternate between rows above and rows below the physical middle of the matrix.

16. The resistor string of claim 15 wherein the row of resistors immediately above the physical middle of the resistor string and the row of resistors immediately below the physical middle of the resistor string are rows of resistors of the same resistor matrix.

17. The resistor string of claim 16 wherein the number of rows of resistors in each resistor string is 8, and wherein the electrical order of the rows is physical row 1, physical row 7, physical row 3, physical row 5, physical row 6, physical row 4, physical row 8, physical row 2.

18. The resistor string of claim 2 wherein M is less than N and wherein each matrix comprises a matrix having a plurality of rows and columns of resistors, the resistors in each matrix being electrically connected so that any two electrically connected rows of resistors in a matrix run in opposite directions across the matrix when traced from the first lead to the second lead, the second matrix being physically smaller and having a lower resistance than the first matrix, a plurality of nodes between resistors in the first matrix each being connected to nominally equipotential nodes between resistors in the second matrix.

19. The resistor string of claim 6 wherein the number of rows in each matrix is an even number, and further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors in the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

20. The resistor string of claim 19 further comprised of a row select transistor coupled to each row line.

39. The resistor string of claim 1 further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors of the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

40. The resistor string of claim 39 further comprised of a row select transistor coupled to each row line.

21. A resistor string comprising:

a first matrix of N resistors connected in series;

a second matrix of M resistors connected in series;

a first lead connected to a first end of the first matrix and to a first end of the second matrix;

a second lead connected to a second end of the first matrix and to a second end of the second matrix;

each matrix comprises a matrix having an even number of rows and a plurality of columns of resistors, each matrix being electrically connected so that any two electrically connected rows of resistors in a matrix run in opposite directions across the matrix when traced from the first lead to the second lead, the first and second matrices having the same number of rows of resistors, the rows of the first and second matrices being physically interleaved;

a plurality of nodes between resistors in the first matrix being connected, each to a nominally equipotential node between resistors in the second matrix.

22. The resistor string of claim 21 wherein for each matrix, given a physical order of rows of 1, 2, . . . N, the first half and the second half of the electrical order of physical rows alternates between rows above and rows below the physical middle of the matrix.

23. The resistor string of claim 22 wherein the row of resistors immediately above the physical middle of the resistor string and the row of resistors immediately below the physical middle of the resistor string are rows of resistors of the same resistor matrix.

24. The resistor string of claim 23 wherein the number of rows of resistors in each resistor string is 8, and wherein the electrical order of the rows is physical row 1, physical row 7, physical row 3, physical row 5, physical row 6, physical row 4, physical row 8, physical row 2.

25. The resistor string of claim 24 further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors of the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

26. The resistor string of claim 25 further comprised of a row select transistor coupled to each row line.

27. The resistor string of claim 26 wherein the current flow in each row of the first matrix, starting from the first lead, is in a different direction across the matrix than the current flow in the respective row of the second matrix, starting from the first lead.

41. The resistor string of claim 21 further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors of the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

42. The resistor string of claim 41 further comprised of a row select transistor coupled to each row line.

28. A resistor string comprising:

a first matrix of N resistors connected in series;

a second matrix of M resistors connected in series;

a first lead connected to a first end of the first matrix and to a first end of the second matrix;

a second lead connected to a second end of the first matrix and to a second end of the second matrix;

each matrix having the same even number of rows and a plurality of columns of resistors, the electrical order of the rows in each matrix being the same as the physical order of rows, thereby forming a snake configuration, the rows of the first and second matrices being physically interleaved with each row of the first matrix, starting from the first lead, being physically adjacent the respective row of the second matrix, starting from the second lead;

a plurality of nodes between resistors in the first matrix being connected, each to a nominally equipotential node between resistors in the second matrix.

29. The resistor string of claim 28 wherein the number of resistors in the second matrix is less than the number of resistors in the first matrix.

30. The resistor string of claim 29 wherein the resistance of the first and second matrices is the same.

31. The resistor string of claim 29 wherein the resistance of the second matrix is less than the resistance of the first matrix.

32. The resistor string of claim 28 wherein, in one of the matrices, the two center rows of resistors are physically adjacent each other without a row of resistors of the other matrix there between.

33. The resistor string of claim 28 further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors in the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

34. The resistor string of claim 33 further comprised of a row select transistor coupled to each row line.

35. The resistor string of claim 34 wherein the current flow in each row of the first matrix, starting from the first lead, is in a different direction across the matrix than the current flow in the respective row of the second matrix, starting from the first lead.

36. A resistor string comprising:

a first matrix of N resistors connected in series;

a second matrix of M resistors connected in series;

a first lead connected to a first end of the first matrix and to a first end of the second matrix;

a second lead connected to a second end of the first matrix and to a second end of the second matrix;

at least one node between resistors in the first matrix being connected to a nominally equipotential node between resistors in the second matrix;

wherein M is less than N and wherein each matrix comprises a matrix having a plurality of rows and columns of resistors, the resistors in each matrix being electrically connected so that any two electrically connected rows of resistors in a matrix run in opposite directions across the matrix when traced from the first lead to the second lead, the second matrix being physically smaller and having a lower resistance than the first matrix, a plurality of nodes between resistors in the first matrix each being connected to nominally equipotential nodes between resistors in the second matrix.

37. The resistor string of claim 36 wherein the number of rows in the first matrix is an even number, and further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors in the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

38. The resistor string of claim 37 further comprised of a row select transistor coupled to each row line.

43. A resistor string comprising:

a first matrix of N resistors connected in series;

a second matrix of M resistors connected in series;

a first lead connected to a first end of the first matrix and to a first end of the second matrix;

a second lead connected to a second end of the first matrix and to a second end of the second matrix;

each matrix comprises a matrix having the same even number of rows and a plurality of columns of resistors, each matrix being electrically connected so that any two electrically connected rows of resistors in a matrix run in opposite directions across the matrix when traced from the first lead to the second lead, the rows of the second matrix when traced from the first lead to the second lead being interconnected in the same order as the rows of the second matrix when traced from the first lead to the second lead, the matrices being physically oriented so that the current flow in each row of the first matrix, starting from the first lead, is in a different direction across the matrix than the current flow in the respective row of the second matrix, starting from the first lead, the rows of the first and second matrices being physically interleaved, a plurality of nodes between resistors in the first matrix being connected, each to a nominally equipotential node between resistors in the second matrix.

44. The resistor string of claim 43 wherein the row of resistors immediately above the physical middle of the resistor string and the row of resistors immediately below the physical middle of the resistor string are rows of resistors of the same resistor matrix.

45. The resistor string of claim 44 wherein the number of rows of resistors in each resistor string is 8, and wherein the electrical order of the rows is physical row 1, physical row 7, physical row 3, physical row 5, physical row 6, physical row 4, physical row 8, physical row 2.

46. The resistor string of claim 45 further comprising a plurality of node select transistors, each having a control terminal controlling the conduction through the respective node select transistor between first and second transistor terminals, each node select transistor having its first terminal coupled to a respective node along the series connection of resistors in the first matrix, the control terminal of the node select transistors in each column being coupled to a respective column select line, and the second terminal of each node select transistor in each row of the array being coupled to a respective row line.

47. The resistor string of claim 46 further comprised of a row select transistor coupled to each row line.

48. The resistor string of claim 47 wherein M=N.

49. The resistor string of claim 47 wherein M is less than N.