Electronics and Telecommunications Research Institute

Korea Advanced Institute of Science and Technology

Seung Hyun Jang

Bong Hyuk Park

Hui Dong Lee

Byoung Whi Kim

Sun Woo Kong

Chul Soo Lee

Eui Suk Jung

Kwang Chun Lee

Jae Ho Jung

Young Kyun Cho

Dong Seung Kwon

Seok Bong Hyun

Kwang Seon Kim

Sung Jun Lee

Seung Hun Wang

Chang Hee Lee

Myung Don Kim

Jin Serk Baik

Nam Sik Ryu

Ki Man Choi

Hyun Sik Min

Keun Youl Park

Eul Suk Jung

Jee Hoon Park

A reconfigurable circuit for differential network includes: first circuit which is a two-port differential circuit; first cross-coupled switch circuit connected to first port on one side of the first circuit in parallel; and second circuit connected to second port on the other side of the first cross-coupled switch circuit in series. The first cross-coupled switch circuit includes: first-series switch disposed between and connected to first terminal of the first port and first terminal of the second port in series; second-series switch disposed between and connected to second terminal of the first port and second terminal of the second port in series; first cross-coupled element disposed between and connected to the first terminal of the first port and the second terminal of the second port; and second cross-coupled element disposed between and connected to the second terminal of the first port and the first terminal of the second port.

Reconfigurable circuit for differential network including cross-coupled switch

A differential transmission line having a switch may comprise: a first transmission line comprising a first distribution element having a first impedance; a second transmission line comprising a second distribution element having a second impedance; and a first switch block connected between a first end of the first transmission line and a first end of the second transmission line, wherein the first switch block comprises a first switch connected in series to the first end of the first transmission line, a second switch connected in series to the first end of the second transmission line, a first-cross capacitor connected between a first terminal of the first switch and a second terminal of the second switch, and a second cross-capacitor connected between a first terminal of the second switch and a second terminal of the first switch.

Differential transmission line having high isolation and configuration method thereof

An amplifier may comprise first and second matching networks; first and second transistors; and a transformer including first to third inductors. Also, a gate and a source of the first transistor are connected to the first matching network, one end of the first inductor is connected to a drain of the first transistor, the other end of the first inductor is connected to a source of the second transistor, one end of the second inductor is connected to a gate of the second transistor, the other end of the second inductor is grounded, one end of the third inductor is connected to a drain of the second transistor, and the other end of the third inductor is connected to the second matching network.

Amplifier for reusing current by using transformer and method thereof

Disclosed are a method for signal modulation based on pulse density modulation and an apparatus therefore. The method for signal modulation is performed in an apparatus for modulating a signal based on pulse density modulation and includes performing pulse density modulation on an analog signal input to the apparatus through a pulse density modulator of the apparatus, converting a bandwidth of the pulse density modulated signal into a bandwidth required for the apparatus through a correlative encoder of the apparatus, transmitting the bandwidth converted signal to a radio frequency (RF) unit of the apparatus based on an electrical-to-optical (E/O) converter and an optical-to-electrical (O/E) converter of the apparatus, filtering a frequency band of the bandwidth converted signal and outputting the frequency band filtered signal via the RF unit.

Method for signal modulation based on pulse density modulation and apparatus therefor

An envelope signal time delay adjustment apparatus includes a negative group delay unit for converting an envelope signal input from a signal generator into an envelope signal having a group delay of a negative value whose frequency increases from a predetermined frequency band; an envelope-tracking modulator for power-amplifying and outputting the envelope signal output from the negative group delay unit; and a frequency limiting unit for limiting a bandwidth of the envelope-tracking modulator to be lower than an original bandwidth of the envelope-tracking modulator.

Apparatus for envelope delay control in an envelope-tracking power amplifier

The present invention relates to a central office device, a remote site device, and a communication method thereof that can be used in a radio over fiber (RoF) technique. Provided are a central office device and a communication method thereof that convert an analog signal into a signal having a carrier with an intermediate frequency and converts the converted signal into a digital signal to transmit the converted digital signal to a remote site device. Provided are a remote site device and a communication method thereof that filter a digital signal having a carrier with an intermediate frequency to easily induce a corresponding analog signal.

Central office device, remote site device, and communication method thoseof

Provided is an apparatus for adjusting an envelope signal delay in an envelope-tracking power amplifier. The apparatus includes: an envelope signal providing unit configured to provide an envelope signal; a variable negative group delay unit configured to adjust a group delay of the envelope signal received from the envelope signal providing unit and output the adjusted envelope signal; an envelope modulator configured to modulate the envelope signal outputted from the variable negative group delay unit; a group delay difference detecting unit configured to detect a group delay difference between the envelope signal which is outputted from the envelope signal providing unit and the envelope signal which is outputted from the envelope modulator; and a control signal generating unit configured to generate a control signal to control a group delay value of the variable negative group delay unit according to the group delay difference.

Apparatus and method for adjusting envelope signal delay in envelope-tracking power amplifier

Disclosed is a technique for a transmission apparatus. A method of generating a differential signal includes adding a predetermined offset to an envelope signal to generate a first signal having the same magnitude as the envelope signal with respect to 0, scaling the first signal at a predetermined rate to generate a second signal, changing a sign of the second signal to generate a third signal that is an inverted signal of the second signal, and forming a differential signal using the second signal and the third signal.

Apparatus and method for generating differential signal, and transmission apparatus and method having the same

A delta-sigma modulator and a transmitter apparatus including the same are disclosed. The delta-sigma modulator includes a first integrator, a second integrator, a first comparator configured to compare an output signal of the second integrator and a reference signal, and output a first comparison signal, a second comparator configured to compare the output signal of the second integrator and the reference signal, and output a second comparison signal, a first DAC configured to output the first signal corresponding to the first comparison signal and the second comparison signal, a second DAC configured to output the second signal corresponding to the first comparison signal and the second comparison signal, a delayer configured to generate a delayed signal that delays the first comparison signal and the second comparison signal by a predetermined time, and an output DAC configured to generate an output signal having a multi-level corresponding to the delayed signal.

Delta-sigma modulator and transmitter including the same

The present invention relates to a passive optical network, which inexpensively improves the spectral efficiency of an access network and is capable of increasing the number of subscribers per channel by using WDM in combination with Time Division Multiplexing (TDM) or SubCarrier Multiple Access (SCMA) to expand a conventional WDM passive optical network. The passive optical network includes light providing means provided in a central office to provide broadband incoherent light; a multiplexer connected to the central office via an optical fiber to divide the light transmitted from the light providing means according to wavelengths and to multiplex upstream signals; a plurality of splitters to branch divided lights and to combine the upstream optical signals; and a plurality of subscribers connected to the splitters, the subscribers including wavelength-locked Fabry-Perot laser diodes capable of performing direct and analog modulation, and means for directly modulating lights of the Fabry-Perot laser diodes and transmitting modulated lights to the subscribers using time division multiplexing.

Optical access network using wavelength-locked WDM optical source injected by incoherent light

Provided are an optical transmission apparatus and an optical access network for a wavelength-division multiplexing optical network with sub-carrier multiplex and sub-carrier multiple access schemes. The optical transmission apparatus includes: a multiplexer and/or demultiplexer demultiplexing M forward A band optical signals having wavelengths each comprising a plurality of sub-carriers and multiplexing M backward B band optical signals having wavelengths each comprising a plurality of sub-carriers; a plurality of optical power splitters splitting each of the M forward A band optical signals into N optical signals; a plurality of optical receivers receiving backward optical signals belonging to a C band; and M optical transmitters converting the backward optical signals in the C band into the M backward B band optical signals.

Optical transmission apparatus and optical access network for wavelength-division multiplexing optical network with both sub-carrier multiplex and sub-carrier multiple access schemes

An apparatus for measuring Optical Beat Interference (OBI) noise is applied to a central office in a Subcarrier Multiple Access (SCMA) optical network. The central office includes an optical receiver for converting an optical signal received through an optical fiber into an electrical signal. The OBI noise measurement apparatus includes a power divider, first and second filters, and a power measurement unit. The power divider divides the power of a signal output from the optical receiver into two signals. The first filter passes one of the two signals divided by the power divider in a low band of frequencies below a band of subcarrier signals. The second filter passes the other of the two signals divided by the power divider in a high band of frequencies above the band of subcarrier signals. The power measurement unit measures the power of each signal passed through the first and second filters.

Apparatus for measuring optical beat interference noise in subcarrier multiple access optical network

Provided are an apparatus and method for processing analog monitoring signals by using a serial bus. The apparatus includes a multiplexer receiving at least one analog signal and outputting only one of the at least one analog signal in response to a predetermined control signal; an analog-to-digital converter converting the output analog signal into a digital signal; a first controller generating the control signal, outputting the control signal to the multiplexer, and controlling the operation of the analog-to-digital converter; and a bus controller outputting the digital signal via an external serial bus. Accordingly, analog monitoring signals are received, converted into digital data, and output via serial bus even when a large number of analog monitoring signals are present, only if the address input to the apparatus is identical to unique address of the apparatus.

Apparatus and method for processing analog signals and outputting digitally converted analog signals using serial bus

An optical transceiver for transmitting light source control information, which is applied to a Subcarrier Multiplexing optical network, is disclosed. The optical transceiver includes a controller, an SCM frame generation/restoring unit, a modulator/demodulator, and an EO/OE converter. The controller controls transmission of light source control information or collects received light source control information. The SCM frame generation/restoring unit generates an SCM frame containing light source control information received from the controller. The modulator/demodulator modulates an SCM frame generated by the SCM frame generation/restoring unit into a signal suitable for transmission. The EO/OE converter converts a transmission signal modulated by the modulator/demodulator into an optical signal and transmits the optical signal through an optical fiber. An optical network having a telephone office OLT and subscriber ONTs, each having the optical transceiver, is also disclosed.

Growing community of inventors

Daejeon, South Korea

Seung Hyun Jang