Method of collecting signals sensed from sensing transistors, corresponding sensor device and imaging camera

Patent metadata

Field	Value
Publication number	US-2022377260-A1
Application number	US-202217745465-A
Country	US
Kind code	A1
Filing date	May 16, 2022
Priority date	May 20, 2021
Publication date	Nov 24, 2022
Grant date	—

Abstract

Current signals indicative of sensed physical quantities are collected from sensing transistors in an array of sensing transistors. The sensing transistors have respective control nodes and current channel paths therethrough between respective first nodes and a second node common to the sensing transistors. A bias voltage level is applied to the respective first nodes of the sensing transistors in the array and one sensing transistor in the array of sensing transistors is selected. The selected sensing transistor is decoupled from the bias voltage level, while the remaining sensing transistors in the array of sensing transistors maintain coupling to the bias voltage level. The respective first node of the selected sensing transistor in the array of sensing transistors is coupled to an output node, and an output current signal is collected from the output node.

First claim

1 . A method for collecting current signals indicative of sensed physical quantities from sensing transistors in an array of sensing transistors, wherein the sensing transistors in the array of sensing transistors have respective control nodes and current channel paths therethrough between respective first nodes and a second node common to the sensing transistors in the array, the method comprising:
applying a bias voltage level to the first nodes of all of the sensing transistors in the array; selecting a sensing transistor in the array of sensing transistors; decoupling the first node of the selected sensing transistor from said bias voltage level while simultaneously maintaining coupling of the first nodes of the sensing transistors in the array of sensing transistors other than the selected sensing transistor to said bias voltage level; coupling the first node of the selected sensing transistor to an output node; and collecting an output current signal from said output node.

2 . The method of claim 1 , wherein selecting comprises sequentially selecting a different sensing transistor in the array of sensing transistors whose first node is decoupled from the bias voltage level, and wherein collecting comprises sequentially collecting current signals provided from each of the sequentially selected sensing transistors.

3 . The method of claim 1 , wherein a plurality of arrangements of matching transistors in the array of sensing transistors are configured to selectively couple respective first nodes of sensing transistors to a biasing voltage source providing the bias voltage level and to the output node in an alternative manner based on a plurality of control signals, wherein decoupling the selected sensing transistor from said bias voltage level while simultaneously maintaining coupling of the first nodes of the sensing transistors in the array of sensing transistors other than the selected sensing transistor to said bias voltage level comprises:
setting a selected control signal of a respective selective arrangement matching the selected sensing transistor to a first value and setting control signals in the plurality of control signals other than the selected control signal to a second value opposite said first value.

4 . The method of claim 3 , comprising:
providing at least one clock signal; producing a binary signal indicative of a number of clock cycles of the at least one clock signal; and producing the control signals based on said binary signal indicative of the number of clock cycles of the at least one clock signal.

5 . The method of claim 1 , wherein at least one reference sensing transistor is configured to provide a blind reference current, the method further comprising:
coupling the selected sensing transistor in the array to the at least one reference sensing transistor; subtracting said blind reference current from a current signal of the selected sensing transistor; and producing a normalized current signal resulting from the subtraction; wherein coupling comprises coupling the normalized current signal to the output node for collection as said output current signal.

6 . The method of claim 5 , further comprising outputing the blind reference current from the reference sensing transistor to at least one further output terminal for collection.

7 . The method of claim 1 , wherein the array of sensing transistors is a planar array, a position of a sensing transistor in the array of sensing transistors and of the matching selective arrangements being identified with a tuple of indices, and wherein the method further comprises:
providing a biasing voltage level and coupling thereto said respective first nodes of sensing transistors and the at least one reference transistor in the array of sensing transistors; selecting a sensing transistor in every row of the array of sensors; decoupling the selected sensing transistor in every row from said bias voltage level while simultaneously maintaining coupled to the bias voltage level the sensing transistors in the array of sensing transistors other than the sensing transistor selected; and coupling each of the selected sensing transistor in every row of the array of sensing transistors to a respective output node in a plurality of output nodes and collecting the respective current signals in parallel therefrom.

8 . A sensor device, comprising:
an array of sensing transistors configured to provide respective current signals indicative of sensed physical quantities, wherein the sensing transistors in the array of sensing transistors have respective control nodes and current channel paths therethrough between respective first nodes and a second node common to the sensing transistors in the array; and circuitry coupled to the array of sensing transistors and configured to collect signals from sensing transistors in the array of sensing transistors by:
applying a bias voltage level to the first nodes of all of the sensing transistors in the array;
selecting a sensing transistor in the array of sensing transistors;
decoupling the first node of the selected sensing transistor from said bias voltage level while simultaneously maintaining coupling of the first nodes of the sensing transistors in the array of sensing transistors other than the selected sensing transistor to said bias voltage level; and
coupling the first node of the selected sensing transistor to an output node; and
collecting an output current signal from said output node.

9 . The sensor device of claim 8 , wherein said sensing transistors in the array of sensing transistors comprise thermal MOS (TMOS) transistors configured to detect infra-red light.

10 . The sensor device of claim 8 , wherein said circuitry is further configured to sequentially select a different sensing transistor in the array of sensing transistors, and sequentially collecting current signals provided from said different selected sensing transistors.

11 . The sensor device of claim 8 , wherein the plurality of arrangements of matching transistors in the array of sensing transistors are configured to selectively couple respective first nodes of sensing transistors to a biasing voltage source and the output node in an alternative manner based on a plurality of control signals, and wherein the circuitry, in decoupling the selected sensing transistor from said bias voltage level while maintaining coupling to said bias voltage level the sensing transistors in the array of sensing transistors other than the selected sensing transistor, is configured to:
set a selected control signal of a respective selective arrangement matching the selected sensing transistor to a first value and set control signals in the plurality of control signals other than the selected control signal to a second value opposite said first value.

12 . The sensor device of claim 11 , wherein the circuitry is further configured to:
provide at least one clock signal; produce a binary signal indicative of a number of clock cycles of the at least one clock signal; and produce the control signals based on said binary signal indicative of the number of clock cycles of the at least one clock signal.

13 . The sensor device of claim 8 , further comprising at least one reference sensing transistor configured to provide a blind reference current, and wherein the circuitry is further configured to:
couple the selected sensing transistor in the array to the at least one reference sensing transistor; subtract said blind reference current from a current signal of the selected sensing transistor; and produce a normalized current signal as a result of the subtraction; wherein

Assignees

• St Microelectronics Srl

Inventors

• Lombardo Pierpaolo
• Vaiana Michele

Classifications

• G01J5/064 Primary

  Ambient temperature sensor; Housing temperature sensor; Constructional details thereof · CPC title

• G01J5/24

  Use of specially adapted circuits, e.g. bridge circuits · CPC title

• G01J2005/0077

  Imaging · CPC title

• G01J5/08

  Optical arrangements · CPC title

• G01J5/20 Primary

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title