Encoder circuit with feedback DAC

Patent metadata

Field	Value
Publication number	US-9810583-B2
Application number	US-201314033917-A
Country	US
Kind code	B2
Filing date	Sep 23, 2013
Priority date	May 17, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A temperature sensing system can include first and second temperature sensing circuits and a digitizing encoder. The first and second temperature sensing circuits can include respective devices with semiconductor junction areas. Temperature information can be determined from one or more characteristic signals measured from the temperature sensing circuits. A feedback circuit can be configured to provide one or more offset signals to the digitizing encoder. The one or more offset signals can correspond to components or characteristics of the first and second temperature sensing circuits. In an example, at least one of the first and second temperature sensing circuits can include an adjustable load circuit for use with the other of the first and second temperature sensing circuits.

First claim

What is claimed is:

1. A sensing system for providing a digital output signal based on analog signals from multiple sensors, the sensing system comprising:
a digitizing encoder circuit having first and second encoder inputs and an encoder output;
a first sensing circuit configured to provide a first analog signal to the first encoder input; and
a second sensing circuit configured to provide a second analog signal to the first encoder input;
wherein the digitizing encoder circuit is coupled to the first sensing circuit and to the second sensing circuit, and the digitizing encoder circuit is configured to encode the first analog signal or the second analog signal into a digital signal, and
wherein the digitizing encoder circuit includes a feedback path with a digital-to-analog converter (DAC) circuit configured to receive an encoder output signal from the encoder output and, in response, provide an analog offset voltage signal at the second encoder input of the digitizing encoder circuit, wherein the offset voltage signal is based on one of the first analog signal from the first sensing circuit and the second analog signal from the second sensing circuit.

2. The sensing system of claim 1 , wherein the second sensing circuit is configured to operate at a selected one of multiple different bias parameter values; and
wherein the first sensing circuit includes a sensing first mode and a load circuit second mode, wherein in the second mode the first sensing circuit is selectively configurable to provide a specified load condition to the second sensing circuit using information about the selected bias parameter of the second sensing circuit.

3. The sensing system of claim 2 , wherein the second sensing circuit includes a semiconductor junction configured to operate at one of multiple different currents; and
wherein the first sensing circuit includes multiple switchable semiconductor junctions configured to use, in the second mode, information about the current through the semiconductor junction of the second sensing circuit to provide a uniform current as the load condition provided to the second sensing circuit.

4. The sensing system of claim 2 , wherein the first sensing circuit includes first and second diodes selectively coupled in parallel;
wherein in response to a first bias current, the first diode is decoupled from the second diode, and the first diode is configured to provide a uniform load condition to the second sensing circuit; and
wherein in response to a different second bias current, the first and second diodes are coupled in parallel and are configured to provide a uniform load condition to the second sensing circuit.

5. The sensing system of claim 4 , wherein the first and second diodes have different semiconductor junction areas.

6. The sensing system of claim 1 , wherein the digitizing encoder circuit includes an offset adjustment circuit configured to generate a first offset signal based on a characteristic of the digitizing encoder circuit, and further configured to generate a second offset signal based on a characteristic of the second sensing circuit;
wherein the digitizing encoder circuit is configured to encode the first analog signal into a temperature-indicating digital signal using the first offset signal, and the digitizing encoder is configured to encode the second analog signal into a temperature-indicating digital signal using the second offset signal.

7. The sensing system of claim 6 , wherein the offset adjustment circuit is configured to generate the second offset signal based on a characteristic semiconductor junction voltage induced by a reference current in the second sensing circuit.

8. The sensing system of claim 1 , wherein the digitizing encoder circuit includes a sigma-delta analog-to-digital converter (ADC) circuit, and wherein the offset voltage signal is generated by successive approximation of the one of the first and second analog signals.

9. The sensing system of claim 8 , wherein the DAC circuit is configured to provide the analog offset voltage signal as a signal between about −10 mV and 10 mV when the offset voltage signal is generated by successive approximation of the first analog signal, and the DAC circuit is configured to provide the analog offset voltage signal as a signal between about 0 V and 1 V when the offset voltage signal is generated by successive approximation of the second analog signal.

10. The sensing system of claim 1 , wherein the second sensing circuit includes first and second diodes arranged in an anti-parallel configuration or first and second diode-connected transistors that are arranged in an anti-parallel configuration.

11. The sensing system of claim 1 , wherein the first sensing circuit includes a diode, and wherein the diode provides the first analog signal as a forward bias voltage of the diode.

12. The sensing system of claim 1 , wherein the second sensing circuit includes a bipolar junction transistor, wherein the base and collector of the transistor are electrically coupled, and wherein the transistor provides the second analog signal as a base-emitter bias voltage of the transistor.

13. The sensing system of claim 1 , wherein the first and second sensing circuits include respective semiconductor devices coupled in series.

14. The sensing system of claim 1 , wherein the second sensing circuit is electrically coupled to a first reference ground, and wherein the digitizing encoder circuit is coupled to a different second reference ground.

15. A sensing system for providing temperature-indicating output signals based on temperature-indicating analog signals from an off-die sensor circuit, the sensing system comprising:
a temperature sensing circuit, located remotely from an integrated circuit die, the temperature sensing circuit configured to provide temperature-indicating analog signals in response to respective different bias parameter values;
a load circuit, included on the integrated circuit die, the load circuit including at least two semiconductor junctions configured to provide an adjustable load condition to the temperature sensing circuit based on information about the selected bias parameter value of the temperature sensing circuit; and
a digitizing encoder circuit, included on the same integrated circuit die as the load circuit, the digitizing encoder circuit coupled to the load circuit and to the temperature sensing circuit, the digitizing encoder circuit configured to encode the temperature-indicating analog signals from the temperature sensing circuit into a temperature-indicating digital signal and wherein the digitizing encoder circuit includes a feedback path with a digital-to-analog converter (DAC) circuit configured to provide an analog offset voltage signal at a different input of the digitizing encoder circuit, wherein the offset voltage signal is based on one of the temperature-indicating analog signals from the temperature sensing circuit.

16. The sensing system of claim 15 , wherein the digitizing encoder circuit includes a sigma-delta analog-to-digital converter (ADC) circuit, and wherein the offset voltage signal provided by the DAC circuit is generated by successive approximation of the one of the temperature-indicating analog signals.

17. The sensing system of claim 15 , wherein the load circuit is configured to provide impedance matching between the temperature sensing circuit and the digitizing encoder circuit according to the load condition provided by the load circuit.

18. The sensing system of claim 15 , wherein the temperature sensing circuit incl

Assignees

• Analog Devices Inc

Inventors

• Bernardinis Gabriele

Classifications

• G01D5/2454

  Encoders incorporating incremental and absolute signals · CPC title

• G01K7/01 Primary

  using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence) · CPC title