Renesas Electronics Corporation

Kosuke Fuwa

Masato Hirai

Yuki Higuchi

Takeshi Kuwano

A reception unit () sequentially selects a plurality of sensor coils and receives a signal from a position indicator via the sensor coil that has been selected, and an operational circuit () detects, using an amplitude value and a phase value of the signal received by the reception unit () via each of the plurality of sensor coils, coordinates of a position indicated by the position indicator and a writing force of the position indicator. When the sensor () includes a sensor capacitor, a transmission unit () outputs a signal to the sensor capacitor, the reception unit () receives a signal generated at a connecting point between the sensor capacitor and the transmission unit (), and the operational circuit () detects whether a touch key corresponding to the sensor capacitor has been touched using a phase value of the signal received by the reception unit ().

Semiconductor device, position detection device, and control method of semiconductor device

A current output circuit includes a separation circuit that separates a digital pseudo sine wave into first and second digital pseudo half-waves, a first digital-to-analog (DA) converter that converts the first digital pseudo half-wave into a first analog half-wave signal, and a second DA converter that converts the second digital pseudo half-wave into a second analog half-wave signal. The pseudo sine wave is represented by a digital code having an n bit width, in which n is a natural number. The separation circuit includes a plurality of OR circuits that output a logical OR between a value of a most significant bit representing a code in the digital code and values of bits other than the most significant bit as the first pseudo half-wave.

Current output circuit

The speed of pen position detection is improved without increasing the circuit area and the current consumption. A sampling circuit samples a signal and outputs sampling data. A arithmetic circuit calculates a real part and an imaginary part of the sampling data. The arithmetic circuit classifies the real part of the sampling data into one of a plurality of groups and classifies the imaginary part of the sampling data into one of the groups according to an order of output of the sampling data from the sampling circuit. Then, the arithmetic circuit adds together real parts of sampling data belonging to a group and adds together imaginary parts of sampling data belonging to a group for each of the groups, and calculates amplitude and phase of the signal by using an addition result of the real parts and an addition result of the imaginary parts of each of the groups.

A current output circuit includes a separation circuit that separates a digital pseudo sine wave into first and second digital pseudo half-waves; a first digital-to-analog (DA) converter that converts the first digital pseudo half-wave into a first analog half-wave signal; a second DA converter that converts the second digital pseudo half-wave into a second analog half-wave signal; and a voltage-current conversion circuit that converts voltages of the first and second half-wave signals into currents and outputs a current obtained by combining the currents, wherein the pseudo sine wave is represented by a digital code having an n (n is a natural number) bit width, and the separation circuit includes: a plurality of OR circuits that output a logical OR between a value of a most significant bit representing a code in the digital code and values of bits other than the most significant bit as the first pseudo half-wave.

Provided is a current output circuitincluding a pseudo sine wave separation circuitthat separates a pseudo sine wave represented by a digital code Din into two pseudo half-waves represented by digital signals Dand D, a DA converterthat converts the pseudo half-wave represented by the digital signal Dinto an analog half-wave signal V, a DA converterthat converts the pseudo half-wave represented by the digital signal Dinto an analog half-wave signal V, and a voltage-current conversion circuitthat converts voltages of the half-wave signals Vand Vinto currents and outputs a current Iout obtained by combining the currents.

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Tokyo, Japan

Kosuke Fuwa