A light-emitting unit outputs an optical signal corresponding to an input electric signal. A light-receiving unit is electrically insulated from the light-emitting unit and outputs an electric signal according to the received optical signal as an output signal. In the light-receiving unit, a first light-receiving device outputs an optical current according to the optical signal. A second light-receiving device is provided not to receive the optical signal. A current duplication circuit duplicates a current flowing through the second light-receiving device. A current-voltage conversion circuit converts a current, which is generated by subtracting the current duplicated by the current duplication circuit from a current flowing through the first light-receiving device, into a voltage signal. A comparator output a result of a comparison between the voltage signal converted by the current-voltage conversion circuit and a threshold voltage as the output signal.

A power source supply circuit includes: a plurality of power sources (11-1, 11-2) that generate power source voltages different from each other; a switch circuit (14) that switches and outputs the power source voltages generated in the plurality of power sources (11-1, 11-2); a voltage output terminal (16) that outputs outside the power source voltages output from the switch circuit (14); an RF choke circuit (15) provided between the switch circuit (14) and the voltage output terminal (16), the RF choke circuit (15) including a first capacitor; and a second capacitor (12-1, 12-2) provided between the plurality of power sources (11-1, 11-2) and the switch circuit (14), the second capacitor (12-1, 12-2) having a larger capacitance than the first capacitor.

Provided is a receiver for human body communication, the receiver including a comparator, a clock and data recovery circuit, and resistors or passive elements having a resistance property in power supply and ground connection units of other digital operation components and a power supply and ground connection unit of a printed circuit board (PCB) to remove or suppress a digital noise reflowed into a human body in the receiver and to raise reception performance by amplifying, with a high gain, a very small transmission signal transmitted through the human body causing a very high loss.

A hybrid combination of analog RF beamforming and digital pre-coding is used to improve signal-to-noise ratio and mitigate interference as between an RF base station and a plurality of wireless receivers within a cell area of the base station. Feedback overhead for beamforming training may be reduced by using indices for identifying the preferred beams of each wireless receiver. Scheduling for channel training may be based on identifying non-colliding ones of the RF beams and assigning these to corresponding wireless receivers which can best use the assigned beams in shared transmission slots.

Method and apparatus for transferring a data signal including receiving a digital data signal by a first data input of a transmitter multiplexer; inverting the digital data signal by a first inverter, thereby providing an inverted digital data signal; receiving the inverted digital data signal by a first inverted data input of the transmitter multiplexer; counting, by a first counter, a clock signal; transmitting, by the first counter and in response to the first counter counting a threshold number of clock cycles, a first selection signal to a first selection signal input of the transmitter multiplexer; and alternately transmitting, in response to the first selection signal and by a first digital data signal output of the transmitter multiplexer, the digital data signal and the inverted digital data signal as the transmitter output signal to a receiver, the receiver and the digital data signal output operably coupled to a data link.

A method and apparatus for removal of a parasitic coupling of a signal source to an output of an antenna array comprising at least one antenna element connected via an associated controllable switch to a signal receiver connected to the output of said antenna array, the method includes measuring a parasitic coupling signal received by the signal receiver connected to the output of said antenna array while all switches of the antenna array are switched off and a first reference signal received by a reference signal receiver; measuring a total reception signal for each antenna element and a second reference signal; calculating a parasitic coupling free reception signal for each antenna element by subtracting a ratio between the measured parasitic coupling signal and the measured first reference signal from a ratio between the total reception signal.

A system and/or method is provided for enhanced listening of audio signals acquired via a telecoil by performing hum filtering. The system may include a telecoil and a telecoil hum filter. The telecoil hum filter may include a comb notch filter. The comb notch filter may include a delay module and a comb notch filter summing module. The telecoil may be operable to receive a magnetic signal and convert the magnetic signal to an input audio signal. The delay module of the comb notch filter may be configured to generate a delayed signal by applying a delay to the input audio signal. The delay may be based on a fundamental hum frequency. The comb notch filter summing module may be configured to generate a comb notch filter output signal by adding the input audio signal and the delay signal.

A surface acoustic wave (SAW) filter that receives an aggregate circuit and outputs two or more sub-signals on outputs each of a different frequency band. The sub-signals are amplified by low noise amplifiers and, in one implementation, the amplified sub-signals can be summed. The outputs are connected via a switched passive network so that portions of the sub-signals on the outputs that are not in the selected frequency band are at least partially terminated.

A surface acoustic wave (SAW) filter that receives an aggregate circuit and outputs two or more sub-signals on outputs each of a different frequency band. The sub-signals are amplified by low noise amplifiers and, in one implementation, the amplified sub-signals can be summed. The outputs are connected via a switched passive network so that portions of the sub-signals on the outputs that are not in the selected frequency band are at least partially terminated.

An example embodiment provides a transceiver for communication includes a timing determiner that detects a fall from high level to low level of a bus signal generated by pulse width modulation of a clock signal and input from a communication bus; a transmission data signal delay adjuster that determines a second timing having a predetermined time difference from a first timing, the bus signal rising from the low level to the high level at the first timing; an encoder that extends a low level of the bus signal by changing a data signal to be output to the communication bus from high level to low level; and a timing adjustment circuit that changes the data signal to the low level at the second timing.