System for driving an array of MEMS structures and corresponding driving method

Patent metadata

Field	Value
Publication number	US-9604842-B2
Application number	US-201514675230-A
Country	US
Kind code	B2
Filing date	Mar 31, 2015
Priority date	May 27, 2014
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

A system for driving a MEMS array having a number of MEMS structures, each defining at least one row terminal and one column terminal, envisages: a number of row driving stages, each for supplying row-biasing signals to the row terminal of each MEMS structure associated to a respective row; a number of column driving stages, each for supplying column-biasing signals to the column terminal of each MEMS structure associated to a respective column; and a control unit, for supplying row-address signals to the row driving stages for generation of the row-biasing signals and for supplying column-address signals to the column driving stages for generation of the column-biasing signals. The control unit further supplies row-deactivation and/or column-deactivation signals to one or more of the row and column driving stages, for causing deactivation of one or more rows and/or columns of the MEMS array.

First claim

The invention claimed is:

1. A system to drive a MEMS array, the system comprising:
a plurality of row driving stages coupled to the MEMS array, the MEMS array having a plurality of MEMS structures that each have a row terminal and a column terminal, each of the plurality of row driving stages being configured to supply row-biasing signals to the row terminal of each MEMS structure associated with a respective row;
a plurality of column driving stages coupled to the MEMS array, each of the plurality of column driving stages being configured to supply column-biasing signals to the column terminal of each MEMS structure associated with a respective column;
a plurality of failure-detection stages coupled to the MEMS array and configured to detect at least one failure associated with one or more of said MEMS structures; and
a control unit configured to supply row-address signals to said row driving stages to generate the row-biasing signals and to supply column-address signals to said column driving stages to generate the column-biasing signals,
the control unit being configured to further supply row-deactivation and column-deactivation signals to one or more of said row and column driving stages to cause deactivation of one or more rows and columns of said MEMS array, the control unit being coupled to said failure-detection stages and configured to identify a position of the failure at the one or more of said MEMS structures and to cause deactivation of the one or more rows and columns of said MEMS array that correspond to said position, the control unit being configured to enable the respective row-deactivation and column-deactivation signals associated with the position of the failure,
wherein each of said row driving stages includes:
a respective row driving stage high-side transistor coupled between the associated row terminal and a respective high-voltage supply terminal configured to receive a high supply voltage;
a respective row driving stage low-side transistor coupled between the associated row terminal and a respective low-voltage supply terminal configured to receive a first intermediate supply voltage; and
a respective row driving stage control block configured to receive the respective row-deactivation signal and to supply control signals to the respective row driving stage high-side and low-side transistors to switch off both said respective row driving stage high-side and low-side transistors

wherein each of said column driving stages includes:
a respective column driving stage high-side transistor coupled between the associated column terminal and a respective high-voltage supply terminal configured to receive a second intermediate supply voltage;
a respective column driving stage low-side transistor coupled between the associated column terminal and a respective low-voltage supply terminal configured to receive a low supply voltage; and

a respective column driving stage control block configured to receive the respective column-deactivation signal and to supply control signals to the respective column driving stage high-side and low-side transistors to switch off both said respective column driving stage high-side and low-side transistors.

2. The system according to claim 1 wherein said MEMS array comprises one or more redundancy rows and columns; and said control unit is configured to activate one or more of said redundancy rows and columns upon deactivation of the one or more rows and columns of said MEMS array.

3. The system according to claim 1 wherein said row and column driving stages are configured, upon reception of the respective row-deactivation or column-deactivation signal to bring into a floating state the associated row terminal or column terminal.

4. The system according to claim 1 wherein each of said column driving stages includes a first unidirectional-conduction element, set between the associated column terminal and the respective high-side transistor and a recirculation circuit branch includes a second unidirectional current-conduction element in series with a recirculation transistor, which are coupled between the associated column terminal and the associated high-voltage supply terminal.

5. The system according to claim 1 wherein the row driving stage includes a first unidirectional-conduction element, set between the associated row terminal and the respective low-side transistor and a recirculation circuit branch includes a second unidirectional current-conduction element in series with a recirculation transistor, which are coupled between the associated row terminal and the associated low-voltage supply terminal.

6. The system according to claim 1 , wherein each of the plurality of failure-detection stages is associated with a respective one of said row driving stages and column driving stages and configured to detect and identify a presence of at least one failure associated with the corresponding MEMS structure.

7. The system according to claim 1 , wherein the plurality of failure-detection stages are coupled to said high-voltage supply terminals and low-voltage supply terminals and are configured to detect a passage of a failure current associated with said terminals that indicates a condition of failure of one or more of the MEMS structures of said MEMS array.

8. The system according to claim 7 wherein said control unit, upon detection of said failure current by said failure-detection stages, is configured to:
supply the row-deactivation and column-deactivation signals to the respective row and column driving stages to deactivate the rows and columns of the MEMS array to cause interruption of the failure current; and
implement a procedure of identification of a position of the failure at said one or more of the MEMS structures of said MEMS array; said identification procedure includes selective activation of each combination of row and column and identification of the position of the failure at the row and column combination that causes passage of the failure current.

9. The system according to claim 7 wherein each of said failure-detection stages includes:
a resistive detection element coupled to a respective high-voltage supply terminal or low-voltage supply terminal and is configured to be traversed by the failure current; and
a comparator block coupled to the resistive detection element and configured to compare a detection voltage indicating a voltage across said resistive detection element with a threshold voltage configured to supply a failure-detection signal.

10. The system according to claim 7 wherein said failure-detection stages include:
a first failure-detection stage coupled in series to the current path towards the high-voltage supply terminal associated with said row driving stages and is configured to detect a failure current coming from said high-voltage supply terminal;
a second failure-detection stage coupled in series to the current path towards the low-voltage supply terminal associated with said row driving stages and is configured to detect a failure current coming from said low-voltage supply terminal;
a third failure-detection stage coupled in series to the current path towards the respective high-voltage supply terminal associated with said column driving stages and is configured to detect a failure current coming from said respective high-voltage supply terminal; and
a fourth failure-detection stage coupled in series to the current path towards the low-voltage supply terminal associated with said column driving stages and is configured to detect a failure current supplied to said respective low-voltage supply terminal.

11. The system according to claim 9 wherein said threshold voltage has an adjustable v

Assignees

• St Microelectronics Srl

Inventors

• Cattani Alberto
• Gasparini Alessandro
• Guanziroli Federico
• Confalonieri Pierangelo

Classifications

• H04R2201/003

  Mems transducers or their use · CPC title

• B81B7/04 Primary

  Networks or arrays of similar microstructural devices · CPC title

• B81B7/008 Primary

  MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00) · CPC title

• B81B2201/0257

  Microphones or microspeakers · CPC title

• B81B3/00

  Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes (B81B5/00 takes precedence) · CPC title