Enhanced linearity, low switching perturbation resistor strings

• US 6,911,896 B2
• Filed: 03/31/2003
• Issued: 06/28/2005
• Est. Priority Date: 03/31/2003
• Status: Expired due to Term

• 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
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US10/403,945
• Publication Number:
  US 20040189438A1
• Time in Patent Office: 820 Days
• Field of Search: 338/260, 338/295, 338/320, 341/153, 341/154
• US Class Current: 338/260
• 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;

each matrix comprises a matrix having an even number of rows and a plurality of columns of resistors, the resistors in each matrix being electrically connected in an order, any two successively connected rows of resistors in a matrix having resistors that are ordered 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;

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;

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

2. The resistor string of claim 1 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.

3. The resistor string of claim 2 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.

4. The resistor string of claim 3 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.

5. The resistor string of claim 4 further comprised of a row select transistor coupled to each row line.

6. The resistor string of claim 5 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.

7. 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 member of rows and a plurality of columns of resistors, the resistors in each matrix being electrically connected in an order, any two successively connected rows of resistors in a matrix having resistors that are ordered 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.

8. The resistor string of claim 7 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.

9. The resistor string of claim 8 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.

10. The resistor string claim 9 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.

11. The resistor string of claim 10 further comprised of a row select transistor coupled to each row line.

12. The resistor string of claim 11 wherein M=N.

13. A resistor string comprising:

a first matrix of N resistors connected in series, the first matrix having a plurality of rows and columns of resistors;

a second matrix of M resistors connected in series, the second matrix having a plurality of rows and columns of resistors;

the first and second matrices having the same number of rows of resistors, the rows of the first and second matrices being physically interleaved,

the resistors in each matrix being electrically connected in an order, any two successively connected rows of resistors in a matrix having resistors that are ordered in opposite directions across the matrix when traced from the first lead to the second lead;

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;

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;

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

14. The resistor string of claim 13 wherein there is an even number of rows of resistors in each matrix.

15. The resistor string of claim 13 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 13 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.

19. The resistor string of claim 18 further comprised of a row select transistor coupled to each row line.