Abstract: A touch screen controller produces a first signal (DATA) representative of a self capacitance (Cselfj) of a touch screen (13A) during a presence scanning mode and representative of mutual capacitances (Cmij) of the screen during a location scanning mode. The first signal is calibrated during the presence scanning and during the location scanning to produce a second signal (?DATA) which may represent either self-capacitance changes (?Cselfj) caused by proximity of an element (22) during presence scanning or mutual capacitance changes (?Cmij) caused the element during location scanning. The second signal is operated upon during presence scanning to determine to determine proximity of the element relative to the screen and during location scanning to produce a magnitude map of the mutual capacitance changes.

Abstract: A capacitance measuring system includes analog-digital circuitry (15) coupled to row conductors (2i) and column conductors (3i) of a touch screen panel (13A) for producing a first digital signal (DATA) representative of cross-coupling capacitances (CSENij). Row drive circuitry (45) superimposes charge transfers from cross-coupling capacitances of the row conductors to a first column conductor to cause the first digital signal to be a convoluted signal. Calibration circuitry (39,40) subtracts base line data from the first digital signal to produce a second digital signal (?DATA) representing touch-induced capacitance change values (?CSENIJ). A deconvolution circuit (44) deconvolutes the second digital signal to produce a digital output (58) representing a magnitude map of the touch-induced capacitance change values.

Abstract: INL error in a SAR ADC (10) is reduced by providing correction capacitors (11B) each having a first terminal connected to a conductor (13) which is also connected to one terminal of the capacitors of a CDAC (11A) and to an input of a comparator (5) of the SAR ADC. Stored INL error information (18A) is utilized to control switches (32) coupled to second terminals of the correction capacitors to selectively couple them to either a ground voltage (GND) or a reference voltage (VREF) in response to the stored INL error information so as to reduce the INL errors.

Abstract: INL error in a SAR ADC (10) is reduced by providing correction capacitors (11B) each having a first terminal connected to a conductor (13) which is also connected to one terminal of the capacitors of a CDAC (11A) and to an input of a comparator (5) of the SAR ADC. Stored INL error information (18A) is utilized to control switches (32) coupled to second terminals of the correction capacitors to selectively couple them to either a ground voltage (GND) or a reference voltage (VREF) in response to the stored INL error information so as to reduce the INL errors.

Abstract: A capacitance measuring system includes analog-digital circuitry (15) coupled to row conductors (2i) and column conductors (3i) of a touch screen panel (13A) for producing a first digital signal (DATA) representative of cross-coupling capacitances (CSENij). Row drive circuitry (45) superimposes charge transfers from cross-coupling capacitances of the row conductors to a first column conductor to cause the first digital signal to be a convoluted signal. Calibration circuitry (39,40) subtracts base line data from the first digital signal to produce a second digital signal (?DATA) representing touch-induced capacitance change values (?CSENIJ). A deconvolution circuit (44) deconvolutes the second digital signal to produce a digital output (58) representing a magnitude map of the touch-induced capacitance change values.