Disclosed is an envelope tracking power supply circuit which can maintain a high efficiency even for a high-frequency signal having a wideband envelope. The envelope tracking power supply circuit (5), for generating an output voltage according to the envelope of a high frequency signal, comprises a voltage follower circuit (7) which receives an envelope signal and outputs a voltage according to the envelope signal (SE), two parallel resistors Rsense connected in parallel between the output of the voltage follower circuit (7) and an output terminal (Po), hysteresis comparators (9a, 9b) which detect voltage drops at the parallel resistors Rsense, respectively, and generate voltages according to the voltage drops, and switching converters (11a, 11b) which perform switching according to the voltages outputted from the hysteresis comparators (9a, 9b), respectively, and output a voltage to the output terminal (Po).

Envelope tracking power supply circuit and high-frequency amplifier including envelope tracking power supply circuit

The dynamic range of existing CMOS image sensors is limited. The present invention introduces an extended dynamic range CMOS pixel sensor circuit. The extended dynamic range CMOS pixel sensor circuit is relatively similar to existing CMOS pixel sensors except that a charge pump has been added to recharge the pixel sensor when the pixel sensor is nearing charge depletion. Every firing of the charge pump is counted. To create a final output for the extended dynamic range CMOS pixel sensor circuit, the number of charge pump firings is combined with a final analog voltage reading of the pixel sensor circuit.

High-dynamic range image sensors

A current driver to which image data including a plurality of grayscale values is input and which outputs an electric current according to the grayscale values of the image data, the current driver comprising: a first input section to which a first reference current is input, a current value of the first reference current being changed according to the grayscale values of the image data; a second input section to which a second reference current is input, the second reference current having a current value different from that of the first reference current; and a current divider circuit which uses the second reference current and the first reference current to output an electric current, the electric current having a value equal to or higher than that of the first reference current and equal to or lower than that of the second reference current.

Current driver and display device

A physical amount detecting apparatus, preferably, an acceleration sensor, includes a sensor element, an A/D converter, a control unit and an activation unit. The sensor element is activated by a supply voltage and outputs an electric signal in accordance with a predetermined physical amount. The A/D converter digitizes an analog electric signal and outputs digital data. The control unit calculates a control amount in order to control the sensor element, as the electric signal is set to a predetermined output, based on the digital data, and generates a control signal in accordance with the control amount. The activation unit activates the sensor element in accordance with the control signal. As a result, the control unit outputs a detecting signal indicating a physical amount in accordance with the control amount or the control signal.

Physical quantity detecting apparatus

The present invention relates to an internal voltage generating circuit. The internal voltage generating circuit comprises a reference voltage generating circuit for generating a reference voltage, which does not depend on an external power supply; and a comparator including a first input terminal, to which the reference voltage is supplied, a second input terminal, for comparing the voltages of the first and second input terminals and generating an output voltage according to the difference thereof at the output terminal; and an impedance element, which is selectively inserted between the output terminal and the second input terminal of the comparator according to an operation mode. An internal power supply voltage, which has a constant voltage during normal operation and has an accurate higher voltage during acceleration test, can be generated at the output terminal by inserting or not inserting a suitable impedance element between the second input terminal and output terminal according to the operation mode. The above-described comparator can be realized by a common differential amplifying circuit, for example. Further, a reference voltage value at normal operation can be fine-tuned by subdividing the impedance element. In the same way, the voltage value at acceleration test can be also fine-tuned by subdividing the impedance element.

Internal voltage generating circuit

A comparator circuit including a reference-voltage generating unit for generating a variable reference voltage, and a comparator having a first input terminal to which an input signal is supplied and a second input terminal to which the variable reference voltage from the reference-voltage generating unit is supplied. The comparator circuit also includes additional-voltage generating unit for generating an additional voltage that varies in proportion to the variable reference voltage, and a switching unit that is connected to the additional-voltage generating unit and activated or deactivated in response to an output of the comparator. When the switching unit is deactivated, the input signal is supplied to the first input terminal of the comparator and the variable reference voltage from the reference-voltage generating unit is supplied to the second input terminal of the comparator. When the switching unit is activated, the additional voltage from the additional-voltage generating unit is added to the input signal, and the sum of the input signal and the additional voltage is supplied to the first input terminal of the comparator so that an interpretation processing of the comparator is performed with a variable hysteresis characteristic corresponding to the additional voltage that varies in proportion to the variable reference voltage.

Comparator circuit with variable hysteresis characteristic

A signal converter includes a frequency-to-voltage converter for converting a frequency of an input signal received via an input terminal into a control voltage. The input signal contains a noise signal having a frequency different from the frequency of the input signal. The control voltage changes in accordance with a change of the frequency of the input signal. A filter has a variable cutoff frequency so that the noise signal is eliminated from the input signal and outputs a filtered signal. The variable cutoff frequency is changed in accordance with a change of the control voltage so that a change of the variable cutoff frequency follows a change of the frequency of the input signal. A comparator compares the filtered signal with a reference voltage and converts the filtered signal into a pulse signal having a pulse width corresponding to the frequency of the input signal.

Kunihiro Matsubara

Papers

Comparator circuit with variable hysteresis characteristic

Signal converter for converting analog signal into pulse signal and control system using the same