A voltage detector comprising, a first voltage reference generator for generating a first voltage reference signal; a second voltage reference generator for generating a second voltage reference signal, wherein the second voltage reference signal is higher than the first voltage reference signal; a trigger, powered by an input signal to the voltage detector, and having an input for receiving either the first or second voltage reference signal and an output for generating a detection signal; and a switch for selectively connecting the input of the trigger to the first or second voltage reference signal, wherein the switch is operative to connect the input of the trigger to the first voltage reference signal when the detection signal output by the voltage detector is low and is operative to connect the input of the trigger to the second voltage reference signal when the detection signal output by the voltage detector is high, and a voltage detector system for monitoring an input signal and outputting a detection signal when a voltage of the input signal meets a first threshold, the voltage detector system comprising: a first voltage detector having an input for receiving the input signal and an output for outputting a detection signal, wherein the first voltage detector is configured to output the detection signal when the voltage of the input signal meets a first rising input voltage threshold, a second voltage detector having an input for receiving the input signal and an output for outputting a detection signal, wherein the second voltage detector is configured to output the detection signal when the voltage of the input signal meets a second rising input voltage threshold which is higher than the first threshold, wherein the output of the second voltage detector controls a connection between the input signal and the input of the first voltage detector such that when the voltage of the input signal meets the second rising input voltage threshold the connection between the input and the input of the first voltage detector is inhibited or disconnected.

A current mirror calibration circuit, coupled to an error amplifier of a pulse-width modulation controller, includes a first voltage generation unit, a second voltage generation unit, a calibration unit and a current mirror circuit. During an initial period, the first voltage generation unit and second voltage generation unit provide a first default voltage and a second default voltage respectively. The current mirror circuit includes a first current unit and a second current unit. The first current unit receives an original current. The second current unit generates a mirror current having a proportional relationship with original current. The first current unit has a first node coupled to the first voltage generation unit and a second node coupled to a third default voltage. The second current unit has a third node coupled to the second voltage generation unit and calibration unit and a fourth node coupled to calibration unit and an output terminal of error amplifier.

A current mirror calibration circuit, coupled to an error amplifier of a pulse-width modulation controller, includes a first voltage generation unit, a second voltage generation unit, a calibration unit and a current mirror circuit. During an initial period, the first voltage generation unit and second voltage generation unit provide a first default voltage and a second default voltage respectively. The current mirror circuit includes a first current unit and a second current unit. The first current unit receives an original current. The second current unit generates a mirror current having a proportional relationship with original current. The first current unit has a first node coupled to the first voltage generation unit and a second node coupled to a third default voltage. The second current unit has a third node coupled to the second voltage generation unit and calibration unit and a fourth node coupled to calibration unit and an output terminal of error amplifier.

A voltage detector (200) for monitoring an input signal and outputting a detection signal at an output when a voltage of the input signal meets a first threshold having: an input configured for receiving the input signal; a voltage reference circuit for receiving an input voltage and producing a reference voltage having a maximum value independent of the input voltage; and a trigger configured to compare the input signal and the reference voltage and to output a detection signal to the output when the voltage of the input signal reaches the first threshold. The voltage reference circuit comprises a reset input connected to either the input or the output and is configured to reduce the reference voltage when a predetermined reset signal is received. The voltage reference circuit may include: an input for receiving the input voltage; a first current controlling element (210), such as a diode, which allows current to flow as an increasing, non-linear function of voltage at least within a first range of voltages; a second current controlling element (240), such as a transistor, which allows current to flow as an increasing, non-linear function of voltage at least with a second range of voltages; and an output at which the output reference voltage is produced. The first current controlling element and the second current controlling element are connected in series between the input and a common reference, with the second current controlling element between the first current controlling element and a common reference, the output comprises a node between the two current controlling elements, the first and second range of voltages overlap and the second current controlling element is configured to vary the function by which it allows current to flow in dependence on the input voltage.

A circuit includes a first transistor having a control terminal and a current path between first and second current path terminals. A second transistor has a control terminal and a current path between first and second current path terminals. The first current path terminal of the first transistor is coupled to the first current path terminal of the second transistor at an intermediate point. A first current buffer has an input and an output. The input of the first current buffer is coupled to the second current path terminal of the first transistor. A second current buffer has an input and an output, the input of the second current buffer being coupled to the second current path terminal of the second transistor. A summation node is coupled to the outputs of the first and second current buffer.

The present invention provides a touch panel and a controlling method thereof. The controlling method comprises: during a display period of the touch panel, turning on a bias voltage generation circuit to generate a bias voltage signal, turning on a reverse bias voltage generation circuit to generate a reverse bias voltage signal, turning on a positive voltage generation circuit to generate a positive voltage signal, turning on a negative voltage generation circuit to generate a negative voltage signal, and turning off a modulating voltage generation circuit; during a touch period of the touch panel, turning off the bias voltage generation circuit, the reverse bias voltage generation circuit, the positive voltage generation circuit, and the negative voltage generation circuit, and turning on the modulating voltage generation circuit to generate a modulating voltage signal, wherein the modulating voltage signal is same as a touch sensing signal of the touch panel.

A current mirror calibration circuit, coupled to an error amplifier of a pulse-width modulation controller, includes a first voltage generation unit, a second voltage generation unit, a calibration unit and a current mirror circuit. During an initial period, the first voltage generation unit and second voltage generation unit provide a first default voltage and a second default voltage respectively. The current mirror circuit includes a first current unit and a second current unit. The first current unit receives an original current. The second current unit generates a mirror current having a proportional relationship with original current. The first current unit has a first node coupled to the first voltage generation unit and a second node coupled to a third default voltage. The second current unit has a third node coupled to the second voltage generation unit and calibration unit and a fourth node coupled to calibration unit and an output terminal of error amplifier.

A current mirror calibration circuit, coupled to an error amplifier of a pulse-width modulation controller, includes a first voltage generation unit, a second voltage generation unit, a calibration unit and a current mirror circuit. During an initial period, the first voltage generation unit and second voltage generation unit provide a first default voltage and a second default voltage respectively. The current mirror circuit includes a first current unit and a second current unit. The first current unit receives an original current. The second current unit generates a mirror current having a proportional relationship with original current. The first current unit has a first node coupled to the first voltage generation unit and a second node coupled to a third default voltage. The second current unit has a third node coupled to the second voltage generation unit and calibration unit and a fourth node coupled to calibration unit and an output terminal of error amplifier.

A Proportional-To-Absolute-Temperature (PTAT) current source is used for high-resolution temperature measurement. The PTAT current source is coupled to a capacitor for a fixed amount of time so as to charge the capacitor to a voltage which is proportional to the current applied to the capacitor, and thus proportional to the temperature. The voltage on the capacitor is measured, and a temperature is calculated or determined from the measured voltage.

A reference current generating circuit includes a current source circuit configured to generate a reference current based on an internal resistor; and a compensation circuit configured to comprise a first compensation circuit comprising a first compensation resistor and a second compensation resistor, and the first compensation resistor and the second compensation resistor are configured to convert the reference current into a first output current and compensate for process variation of the current source circuit.