Freescale Semiconductor,inc.

Nxp Usa, Inc.

Liang Qiu

Xiaolei Wu

Bin Feng

John M Pigott

Meng Wang

Wenzhong Zhang

Meng Liu

A voltage regulation system has a voltage regulator, a current-limiting circuit, and a feed-forward circuit. The voltage regulator regulates an output voltage to a desired voltage level. The current-limiting circuit controls an output current of the voltage regulator to a desired current level. The feed-forward circuit, which has a fast response time, controls an inrush current in the output current caused by a decrease in an output voltage.

Voltage regulator with current-limiting and feed-forward circuit

An electronic device includes mutual capacitance sensing circuitry for a capacitive touch pad. The touch pad has pairs of transmit and receive electrodes. The sensing circuitry intermittently charges and discharges the transmit electrode, and then measures corresponding voltage level changes at the receive electrode. A non-linear voltage-to-current converter is used to detect the voltage level changes, which allows for great sensitivity to mutual capacitance changes.

Mutual capacitance sensing circuit with increased sensitivity

A sensor for providing an output signal that is a function of a sensed capacitance, in a touch interface for example. The sensor includes a charger for repetitively applying first and second voltages to charge the sensed capacitance to first and second charge values in first and second phases respectively. A sampler provides first and second sample signals that are a function of the first and second charge values respectively. An accumulator uses an accumulator signal to provide the output signal. The accumulator repetitively uses the first sample signal incrementally and the second sample signal decrementally in providing the accumulator signal. The accumulator signal is a progressive function of the sensed capacitance but tends to cancel a noise in the first and second sample signals at frequencies less than a repetition rate of operation of the accumulator.

Capacitance sensor with noise rejection

In a touch interface, a sensor provides an output signal that is a function of a sensed capacitance. The sensor includes a charger for repetitively applying first and second voltages to charge the sensed capacitance to first and second charge values in first and second phases respectively. A sampler includes a first current mirror for providing first and second sample current signals that are a function of the first and second charge values respectively. An accumulator uses an accumulator signal to provide the output signal. The accumulator repetitively uses the first and second sample current signals differentially to modify a charge on an accumulator capacitor and provide the accumulator signal. The accumulator signal is a progressive function of the sensed capacitance but cancels noise in the first and second sample signals at frequencies less than a repetition rate of operation of the accumulator.

A spread-spectrum clock (SSC) generator for generating an SSC signal. The SSC generator has a first up/down counter that operates for a fixed, first duration (t1), a first PRBS generator that operate for a variable, second duration (t2), a second up/down counter that operates for a fixed, third duration (t3), and a second PRBS generator that operates for a variable, fourth duration (t4). A state machine sequentially triggers the first counter and the first PRBS generator to generate a positive portion of a cycle of the SSC signal and then sequentially triggers the second counter and the second PRBS generator to generate a negative portion of the cycle of the SSC signal. For a set of parameters stored in configurable registers, the first and third durations are fixed from cycle to cycle, while the second and fourth durations vary from cycle to cycle.

Spread-spectrum clock generator

A voltage level shifter for high voltage applications has a low voltage domain current mirror having first and second branches. A high voltage switch and a resistor are connected in series with the second branch. An output stage provides an output signal that is a function of a voltage difference across the resistor, and the output stage and the resistor are in the high voltage domain. Assertion of an input signal in the low voltage domain develops a first current in the first branch, and causes the high voltage switch to pass in the resistor a second current from the second branch that is a function of the first current and develops the voltage difference across the resistor. Only the high voltage switch needs to have high breakdown voltage characteristics.

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Tianjin, China

Liang Qiu