Holtek Microelectronics Inc.

Rong-Tyan Wu

Chern-Jsair Chang

Herman Chung

Chi-Yung Wu

An intelligent bias voltage generating circuit capable of providing an electronic device with a reliable bias signal includes a power input terminal which is electrically connected to a power generating device for providing a power input, and a bias voltage generating circuit which is electrically connected to the power input terminal for responding to power fluctuations and generating a bias voltage signal output by a multi-section linear variation method.

Intelligent bias voltage generating circuit

An adjustable-period dual-tone multifrequency (DTMF) generator, which includes a plurality of programmable counters or up/down counters, a control unit, a memory unit for storing data, a digital adder, and a digital-to-analog converter. The programmable counter and the control unit are combined together to form into at least two programmable counting address generators, in which the circuit is a digit-process circuit for overcoming the problem of signal distortion that usually exists in an analog circuit.

Adjustable-period dual-tone multifrequency generator

The present invention relates to methods and devices for generating cycled waveforms of nonsingle period, and more particularly to an improvement from the one-way counter used by conventional cycled waveform generator of nonsingle period into an up-down counter or a programmable up-down counter, along with an adder/subtracter. Thus, only the varied values in waveform relative to a DC level have to be filled into a table, and then the varied values in waveform (i.e. the digital waveform sampling values) are input into said adder/subtracter to obtain a periodic digital values by adding/subtracting with a predetermined DC level. Finally, cycled waveforms of nonsingle period are obtained by digital-to-analog converting of said digital values. With the methods and devices of the present invention, not only the fillings in said table can be decreased to reduce the cost, but also the DC output level can be fixed or adjusted arbitrarily for convenient signal processing.

Methods and devices for generating cycled waveforms of nonsingle period

A cycle-modulating DTMF generator for generating a DTMF signal; the generator comprises a programmable time-pulse generator, counters or up/down counters, a memory unit for storing data, a digital adder, and a digital-to-analog converter. The circuit of such generator is substantially a digital circuit so as to overcome the problem of signal distortion, which usually exists in an analog circuit.

Cycle-modulating type of dual-tone multifrequency generator

A multi-function telephone dialer display device which is equipped with a display screen for displaying the use status and the caller identification information, and a dialer for responding to data input and for generating a data signal to the display screen to display the corresponding use status. When dialing with numerical keys, with standard non-numerical keys or when setting up a function, the data signal is coded into a numerical code representing the original digit, coded into a standard non-numerical code representing the original non-numerical keys or coded into a function key code representing the function, respectively. A display driver is electrically connected to the display screen, to the telephone dialer and to a caller data signal line for receiving and processing the data signals, the timing signals and the identification signal representing the caller information, and then transferring the result of the processing to the display screen for displaying a corresponding status and caller identification information.

Multi-function telephone dialer display

The present invention is related to a display control device adapted to be used in a communication apparatus providing an information for transmitting the information to a display and transmitting the information to a second device when the information is required by the second device, which includes a buffer device storing therein the information, a decoder electrically connected to the buffer device for decoding the information stored in the buffer device and outputting the decoded information to the display, a bidirectional transmission device electrically connected to the buffer device for transmitting the information to the display and transmitting the information to the second device when the information is required by the second device, and a controller electrically connected to the bidirectional transmission device for controlling a transmission between the bidirectional transmission device and the second device. The present invention receives information and transmits received information to a display and/or another circuit through a simple structure.

Display control device allowing information transmission to both display

A monitor-controlling device is disclosed. The monitor-controlling device, used for a system having a monitor and a first circuit, includes a buffer for storing data from the system; a decoder electrically connected to the buffer for receiving and decoding the data; a bi-directional transmitter electrically connected to the buffer for providing the buffer with a path to transmit the data to the first circuit; and a controlling circuit electrically connected to the bi-directional transmitter for controlling the path on or off.

Monitor-controlling device

This present invention relates to a level-shift type digital to analog converter including a selection circuit, a multiple voltage level generation circuit, a stabilization circuit and a level-shift type buffer stage circuit. The multiple voltage level generation circuit is composed by a divided-step voltage output circuit and a level voltage output circuit, for generating a plurality of voltage levels to directly output to a level-shift type buffer stage circuit or alternatively, to be processed through voltage selection in order to respectively output the divided-step voltage output values and the level voltage output values to a level-shift type buffer stage circuit. A stabilization circuit generates a reference voltage or a reference current insensitive to the power supply voltage V.sub.DD for other elements of the converter. Finally, the level-shift type buffer stage circuit synthesizes the received divided-step voltage and the level voltage, amplifies them with appropriate times and finally converts them to analog output signals.

Level-shift type digital to analog converter

A cost effective waveform-generating apparatus that generates accurate and precise waveforms is disclosed. The present waveform-generating apparatus includes a memory for storing a sequence of sampled amplitudes of a waveform, said sampled amplitudes constituting at least two periods of said waveform; a counting circuit, electrically connected to the memory, responsive to a clock signal for generating counting signals; a controlling circuit, electrically connected to the memory and the counting circuit, responsive to the counting signals for controlling the memory to output the sampled amplitudes recurrently; and a digital to analog converter, electrically connected to the memory, for converting the recurrent sampled amplitudes into an analog output.

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Hsinchu, Taiwan

Rong-Tyan Wu