Electrically trimmable resistor device and trimming method thereof

Patent metadata

Field	Value
Publication number	US-9230720-B2
Application number	US-201313924159-A
Country	US
Kind code	B2
Filing date	Jun 21, 2013
Priority date	Jun 22, 2012
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

An integrated circuit has a circuit part and a trimmable resistor, the resistance whereof may be modified by Joule effect. The trimmable resistor has first and second connection terminals coupled to the circuit part, and an intermediate terminal that divides the trimmable resistor into two portions. The first and the second connection terminals and the intermediate terminal are coupled to respective pads configured to receive electrical quantities designed to cause, in use, a respective trimming current flow in each portion. In this way, a substantially zero voltage drop is maintained between the first and second connection terminals while current is flowing in the resistor to change an electrical characteristic of the resistor, such as resistance or thermal coefficient.

First claim

The invention claimed is:

1. A circuit, comprising:
a circuit part;
first and second connection pads; and
a trimmable resistor trimmable by Joule effect, the trimmable resistor having:
first and second connection terminals electrically coupled to the circuit part, at least one of the first and second connection terminals being configured to be electrically coupled in a trimming phase to the first connection pad;
an intermediate terminal electrically coupled to the second connection pad; and
first and second resistor portions, the first resistor portion positioned between the first connection terminal and the intermediate terminal and the second resistor portion positioned between the second connection terminal and the intermediate terminal, the first and second connection pads being configured to receive a substantially zero voltage drop between the first and the second connection terminals and the intermediate terminal being configured to receive an electrical quantity able to generate in the first and second resistor portions respective trimming current flows that modify an electric characteristic of the trimmable resistor.

2. The circuit of claim 1 , comprising a trimming circuit having:
an electrical quantity source coupled to the intermediate terminal of the trimmable resistor; and
a connection circuit configured to electrically couple the first and second connection terminals to each other;
the trimming circuit being configured to generate the respective trimming current flows that modify the electric characteristic of the trimmable resistor while maintaining the substantially zero voltage drop between the first and the second connection terminals.

3. The circuit according to claim 2 , wherein the electrical characteristic is one of electrical resistance and temperature coefficient and the trimming circuit is configured to cause the current flows to modify the resistance or the temperature coefficient of the trimmable resistor.

4. The circuit according to claim 2 , wherein the electrical quantity source is a voltage source.

5. The circuit according to claim 2 , wherein the electrical quantity source is configured to apply current pulses to the intermediate terminal.

6. The circuit according to claim 2 , wherein the trimming circuit comprises:
a resistance measure circuit configured to measure a resistance of the trimmable resistor and provide a resistance measurement signal; and
a control unit configured to control the electrical quantity source based on the resistance measurement signal.

7. The circuit according to claim 6 , wherein:
the electrical quantity source has a first terminal, electrically coupled to the intermediate terminal, and a second terminal; and
the resistance measure circuit includes:
a first current gauge electrically coupled between the first connection terminal and the second terminal of the electrical quantity source; and
a second current gauge electrically coupled between the second connection terminal and the second terminal of the electrical quantity source.

8. The circuit according to claim 1 , further comprising a first and a second switch series-coupled between the first and the second connection terminals of the trimmable resistor.

9. The circuit according to claim 8 , wherein the first and the second switches respectively are first and second transistors having respective first and second terminals and a control terminal, the first terminal of the first transistor being coupled to the first connection terminal of the trimmable resistor, the first terminal of the second transistor being coupled to the second connection terminal of the trimmable resistor, the second terminals of the first and the second transistors being coupled to each other and to the first connection pad and the control terminals of the first and the second transistors being coupled to each other, the first and second transistors being configured to be on during the trimming phase and off during an operating phase of the integrated circuit.

10. The circuit according to claim 9 , further comprising a third connection pad electrically coupled to the control terminals of the first and second transistors, the first and third connection pads being configured to be biased so as to turn on the first and the second transistors during the trimming phase and turn off the first and the second transistors during the operating phase of the integrated circuit.

11. The circuit according to claim 1 , wherein the trimmable resistor has a structure selected from among: linear, zigzag and spiral-like.

12. The circuit according to claim 1 , further comprises a third connection pad, wherein the first and second connection pads are directly connected to the first and second connection terminals.

13. The circuit according to claim 1 , wherein the trimmable resistor is configured to generate, in response to the electrical quantity, the trimming current flows that both enter the intermediate terminal.

14. The circuit according to claim 1 , wherein the trimmable resistor is configured to generate, in response to the electrical quantity, the trimming current flows that both exit the intermediate terminal.

15. A trimming method, comprising:
applying a substantially zero voltage drop between first and second connection terminals of a trimmable resistor;
simultaneously with applying the substantially zero voltage drop, applying a non-zero electrical quantity to an intermediate terminal that divides the trimmable resistor into first and second resistor portions; and
generating a first trimming current flow in the first resistor portion and a second trimming current flow in the second resistor portion, the first and second current flows causing a change in an electrical characteristic of the trimmable resistor.

16. The trimming method according to claim 15 , wherein the electrical quantity is a voltage.

17. The trimming method according to claim 15 , wherein the electrical characteristic of the trimmable resistor is one of electric resistance and temperature coefficient.

18. The trimming method according to claim 15 , further comprising interrupting applying the electrical quantity, measuring a change in the electrical characteristic of the trimmable resistor, and repeating applying the electrical quantity.

19. The trimming method according to claim 15 , wherein measuring the change in the electrical characteristic of the trimmable resistor comprises:
before performing applying the substantially zero voltage drop and applying the non-zero electrical quantity:
biasing an integrated circuit that includes a circuit part and the trimmable resistor;
measuring an electrical quantity of the integrated circuit;
disconnecting the integrated circuit from a supply source; and

after applying the substantially zero voltage drop, applying the non-zero electrical quantity, and generating the first and second trimming current flows, repeating the biasing and measuring the electrical quantity of the integrated circuit, followed again by applying a zero voltage drop, the applying a non-zero electrical quantity, and the generating a first and a second trimming current flows until reaching a desired value for said electrical quantity of the integrated circuit.

20. The trimming method according to claim 15 , wherein the first and second current flows both enter the intermediate terminal.

21. The trimming method according to claim 15 , wherein the first and second current flows both exit the intermediate terminal.

Assignees

• St Microelectronics Srl

Inventors

• Santangelo Antonello
• Privitera Stefania Maria Serena

Classifications

• H10P74/207

  Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics · CPC title

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H10W20/498

  Resistive arrangements or effects of, or between, wiring layers · CPC title

• H01C10/50 Primary

  structurally combined with switching arrangements (H01C10/36 takes precedence) · CPC title

• H01C17/232 Primary

  Adjusting the temperature coefficient; Adjusting value of resistance by adjusting temperature coefficient of resistance · CPC title