Chemical sensor array with leakage compensation circuit

• US 8,742,471 B2
• Filed: 03/21/2013
• Issued: 06/03/2014
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: Life Technologies Corporation (Thermo Fisher Scientific Incorporated)
• Original Assignee: Life Technologies Corporation (Thermo Fisher Scientific Incorporated)
• Inventors: Fife, Keith G.
• Primary Examiner(s): MENZ, LAURA MARY
• Application Number:
  US13/848,444
• Publication Number:
  US 20130214795A1
• Time in Patent Office: 439 Days
• Field of Search: 257/253, 257/292, 257/316
• US Class Current: 257/253
• CPC Class Codes: C12Q 1/6869 Methods for sequencing
• CPC Class Codes: G01J 1/46 using a capacitor
• CPC Class Codes: G01N 27/4143 Air gap between gate and channel, i.e. suspended gate [SG] FETs work function measurement per se G01N27/002
• CPC Class Codes: G01N 27/4145 specially adapted for biomolecules, e.g. gate electrode with immobilised receptors
• CPC Class Codes: G01N 27/4148 Integrated circuits therefor, e.g. fabricated by CMOS processing CMOS processing per se H01L21/82
• CPC Class Codes: G01N 33/00 Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
• CPC Class Codes: G01R 29/26 Measuring noise figure; Measuring signal-to-noise ratio
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 29/66 Types of semiconductor device ; Multistep manufacturing processes therefor
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: Y10T 436/25875 Gaseous sample or with change of physical state

Abstract

To reduce the pixel size to the smallest dimensions and simplest form of operation, a pixel may be formed by using only one ion sensitive field-effect transistor (ISFET). This one-transistor, or 1T, pixel can provide gain by converting the drain current to voltage in the column. Configurable pixels can be created to allow both common source read out as well as source follower read out. A plurality of the 1T pixels may form an array, having a number of rows and a number of columns and a column readout circuit in each column.

Claims

1. A device comprising:

an array of chemically-sensitive field-effect transistors (chemFETs) coupled to a plurality of lines; and

a circuit for reading a selected chemFET in the array, the selected chemFET coupled to a first line and a second line in the plurality of lines, the circuit to;

induce a current between the first line and the second line through the selected chemFET to establish a voltage on the second line;

compensate for leakage current through at least one additional chemFET coupled to the second line; and

read the selected chemFET based on the voltage on the second line.

2. The device of claim 1, wherein the circuit includes a current sink coupled to the second line to compensate for the leakage current.

3. The device of claim 1, wherein the voltage on the second line indicates an ion-concentration of an analyte solution coupled to the selected chemFET.

4. The device of claim 1, wherein the circuit includes a pre-charge circuit to pre-charge the second line to a pre-charge voltage level.

5. The device of claim 4, wherein the pre-charge circuit comprises a switch coupled between the second line and a reference voltage.

6. The device of claim 1, wherein the circuit includes a sample circuit to sample the voltage level on the second line to read the selected chemFET.

7. The device of claim 6, wherein the sample circuit includes a sample and hold circuit to hold an analog value of the voltage on the second line, and an analog to digital converter to convert the analog value to a digital value.

8. The device of claim 6, wherein the sample circuit includes an analog to digital converter to directly convert the voltage on the second line to a digital value.

9. The device of claim 1, wherein the circuit to compensate for the leakage current establishes a minimum current level on the second line.