Capacitive charge pump
First Claim
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1. A device comprising:
- an array of chemically-sensitive field-effect transistors (chemFETs), chemFETs in the array including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer;
a plurality of column lines and a plurality of row lines coupled to chemFETs in the array of chemFETs; and
circuitry coupled to the plurality of column lines and the plurality of row lines for reading a selected chemFET coupled to a selected column line and a selected row line, the circuitry comprising;
bias circuitry to apply a read voltage to the selected row line during a read interval; and
charge pump circuitry comprising;
a plurality of capacitors;
a first set of switches responsive to a first switching signal to connect the plurality of capacitors in parallel to sample a voltage level on the selected column line at a circuit node during a first stage of the read interval; and
a second set of switches responsive to a second switching signal to connect the plurality of capacitors in series to amplify the sampled voltage level at the circuit node during a second stage of the read interval.
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Abstract
One or more charge pumps may be used to amplify the output voltage from a chemically-sensitive pixel that comprises one or more transistors. A charge pump may include a number of track stage switches, a number of boost phase switches and a number of capacitors. The capacitors are in parallel during the track phase and in series during the boost phase, and the total capacitance is divided during the boost phase while the total charge remains fixed. Consequently, the output voltage is pushed up.
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Citations
12 Claims
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1. A device comprising:
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an array of chemically-sensitive field-effect transistors (chemFETs), chemFETs in the array including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer; a plurality of column lines and a plurality of row lines coupled to chemFETs in the array of chemFETs; and circuitry coupled to the plurality of column lines and the plurality of row lines for reading a selected chemFET coupled to a selected column line and a selected row line, the circuitry comprising; bias circuitry to apply a read voltage to the selected row line during a read interval; and charge pump circuitry comprising; a plurality of capacitors; a first set of switches responsive to a first switching signal to connect the plurality of capacitors in parallel to sample a voltage level on the selected column line at a circuit node during a first stage of the read interval; and a second set of switches responsive to a second switching signal to connect the plurality of capacitors in series to amplify the sampled voltage level at the circuit node during a second stage of the read interval. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for reading a selected chemically-sensitive field effect transistor (chemFET) including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer, the selected chemFET coupled to a selected column line and a selected row line, the method comprising:
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applying a read voltage to the selected row line during a read interval; connecting a plurality of capacitors in parallel to sample a voltage level on the selected column line at a circuit node during a first stage of the read interval; and connecting the plurality of capacitors in series to amplify the sampled voltage level at the circuit node during a second stage of the read interval. - View Dependent Claims (9, 10, 11, 12)
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Specification