Texas Instruments Corporation

Shigetoshi Nakao

Toshihiko Hamasaki

Hitoshi Kondoh

Masahito Satoh

A time division multiplex transmission system transmits information on multiple channels by using a transmission path with variable time division multiplexing. The variable time division multiplex transmission system of this invention is equipped with multiple channel devicesand a single transmission pathconnected to these multiple channel devices. The multiple channel devicestransmit or receive data over the transmission path. Additionally, the system is equipped with a circuit that determines consecutive time slots for using the transmission path, and each of the channel devices transmits or receives data using consecutive time slots. Data can be transmitted in two or more different transmission bands, and the different transmission bands are realized by making the number of time slots used for a communication frame different.

Variable time division multiplex transmission system

A digital-to-analog (D/A) converter with a required accuracy can be implemented in a smaller chip area and at a lower cost. The D/A converter comprises a decoder which receives a digital input signal comprised of a first number of bits, and divides the first number of bits into a second number of bit groups. Bit group converters equal in number to the second number, are provided for the second number of bit groups, and each selects and uses a form of weight for each of the bit groups associated therewith to convert the bit group into an analog form in response to the second number of bit groups, thereby generating the second number of bit group analog outputs. An adder adds the second number of the bit group analog outputs to form an analog signal output representative of the digital signal input.

Digital-to-analog converting method and digital-to-analog converter

A method and apparatus for improving an S/N ratio in a digital-to-analog conversion of a PDM signal are provided. A digital-to-analog conversion system comprises an S/N ratio improving section. The S/N ratio improving section has a signal component extractor which extracts a signal component included in the PDM signal, and outputs a digitally filtered output signal. The digitally filtered output signal has a second full scale smaller than a first full scale of the PDM signal. The S/N ratio improving section also comprises a full-scale matching unit which matches the second full scale of the digitally filtered output signal with a third full scale of digital-to-analog conversion.

Method and apparatus for improving S/N ratio in digital-to-analog conversion of pulse density modulated (PDM) signal

A digital-to-analog converter is provided for accomplishing analog output characteristics using different digital-to-analog conversion type digital signal processing schemes. A plurality of bits of a received digital signal are divided into a plurality of bit groups. A digital signal processing unit includes a plurality of bit group digital signal processors for receiving the plurality of bit groups. The plurality of digital signal processors employ one or more digital-to-analog conversion type digital signal processing schemes for generating a plurality of digital signal processed outputs. The converter adds the plurality of digital signal processed outputs to generate a composite signal processed output, and includes a weight generating unit for controlling a plurality of shared weight generating elements in response to the composite digital signal processed output to generate an analog output signal.

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Tokyo, Japan

Shigetoshi Nakao