TEMPERATURE SENSOR WITH DIGITAL BANDGAP

• US 20080259998A1
• Filed: 10/01/2007
• Published: 10/23/2008
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kutz, Harold, Mar, Monte, Venkataraman, Garthik
• Granted Patent: US 8,092,083 B2
• Time in Patent Office: Days
• US Class Current: 374/170
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: H03K 5/2481 with at least one differential stage
• CPC Class Codes: H03K 5/249 using clock signals
• CPC Class Codes: H03M 3/43 the quantiser being a single bit one
• CPC Class Codes: H03M 3/456 the modulator having a first order loop filter in the feedforward path

Abstract

A system comprises a temperature sensor generate multiple base-emitter voltage signals by sequentially providing various currents to a transistor, and a system controller to determine a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.

Claims

1. A method comprising:

generating multiple base-emitter voltage signals by sequentially providing various currents to a transistor;

determining a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.

2. The method of claim 1

generating a first base-emitter voltage signal when a first current signal is provided to the transistor;

generating a second base-emitter voltage signal when a second current signal is provided to the transistor;

determining a difference between the first base-emitter voltage signal and the second base-emitter voltage signal;

determining the differential voltage signal, at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal.

3. The method of claim 2 includes

generating a third base-emitter voltage signal when a third current signal is provided to the transistor;

determining difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal; and

determining the differential voltage signal, at least in part, according to the determined difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal.

4. The method of claim 3 where determining the differential voltage signal includes averaging multiple differences determined between various base-emitter voltage signals.

5. The method of claim 3 where determining the differential voltage signal includes selecting one of the differences to represent the differential voltage signal.

6. The method of claim 1 where the multiple base-emitter voltage signals are analog base-emitter voltage signals;

and

converting the analog base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal.

7. The method of claim 1 where converting the analog base-emitter voltage signals to digital base-emitter voltage signals is performed by a passive analog-to-digital converter.

8. A system comprising:

means for generating multiple base-emitter voltage signals by sequentially providing various currents to a transistor;

means for determining a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.

9. The method of claim 8

means for generating a first base-emitter voltage signal when a first current signal is provided to the transistor;

means for generating a second base-emitter voltage signal when a second current signal is provided to the transistor;

means for determining a difference between the first base-emitter voltage signal and the second base-emitter voltage signal;

means for determining the differential voltage signal at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal.

10. The method of claim 9 including

means for generating a third base-emitter voltage signal when a third current signal is provided to the transistor;

means for determining difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal; and

means for determining the differential voltage signal, at least in part, according to the determined difference between at least one of the first base-emitter voltage signal and the third base-emitter voltage signal or the second base-emitter voltage signal and the third base-emitter voltage signal.

11. The method of claim 10 including means for averaging multiple differences determined between various base-emitter voltage signals to determine the differential voltage signal.

12. The method of claim 10 including means for selecting one of the differences to represent the differential voltage signal to determine the differential voltage signal.

13. The method of claim 8 where the multiple base-emitter voltage signals are analog base-emitter voltage signals;

and

means for converting the analog base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal.

14. A system comprising:

a temperature sensor generate multiple base-emitter voltage signals by sequentially providing various currents to a transistor;

a system controller to determine a differential voltage signal according to the multiple base-emitter voltage signals, the differential voltage signal proportional to an environmental temperature associated with the transistor.

15. The system of claim 14 where the temperature sensor includes a variable current source to generate a first current signal and provide the first current signal to the transistor to generate a first base-emitter voltage signal, and to generate a second current signal and provide the second current signal to the transistor to generate a second base-emitter voltage signal.

16. The system of claim 15 where the variable current source includes a plurality of fixed current sources that are selectively activated when generating various current signals.

17. The system of claim 16 including a switch network to selectively couple one or more of the fixed current sources to the transistor.

18. The system of claim 17 where the temperature sensor includes a sequencer to direct the switch network to couple one or more of the fixed current sources to the transistor when prompted by the system controller.

19. The system of claim 15 where the system controller is configured to determine a difference between the first base-emitter voltage signal and the second base-emitter voltage signal, and to determine the differential voltage signal, at least in part, according to the determined difference between the first base-emitter voltage signal and the second base-emitter voltage signal.

20. The system of claim 14 including an analog-to-digital converter to convert base-emitter voltage signals to digital base-emitter voltage signals for use in determining the differential voltage signal, where the analog-to-digital is a passive converter.