Fci, Inc.

Myung-Woon Hwang

Min-Chul Kang

In-chul Hwang

Je-cheol Moon

Hyun-ha Jo

Seong-Heon Jeong

An adaptive power amplifier and a radio frequency transmitter thereof are described. The radio frequency transmitter is a transmitter to transmit a transmission signal for a wireless communication system. The radio frequency transmitter includes at least one direct-current (DC) to direct-current (DC) converter coupled to an external power supply device for operation, a digital-to-analog converter configured to convert a digital signal into an analog signal, a filter configured to filter a harmonic component of the analog signal to generate an input signal, a RF up-converter configured to up-convert the input signal according to a desired channel frequency for generating a modulated signal, and a power amplifying circuit coupled to the DC-to-DC converter and the external power supply device, for selectively receiving one of different supply voltages for operation, and amplifying the modulated signal to generate a RF output signal.

Adaptive power amplifier and radio frequency transmitter thereof

A dual operation mode power amplifier is disclosed. In the power amplifier in accordance with an embodiment of the present invention, a bias circuit part can be converted to decrease power consumption. Different from the prior art, performance of the present invention is not reduced in a high power mode, and no additional passive components like inductors or transformers with a large area are necessary to be further added. Furthermore, a tunable impedance matching circuit provides impedances respectively matching impedances of a fully differential amplifier and a single-ended amplifier, thereby improving the performance of the power amplifier.

Dual operation mode power amplifier

An apparatus for receiving signals in a radio frequency system includes a low noise amplifier that amplifies and filters a signal received from an antenna; a first frequency mixer that mixes the signal output from the low noise amplifier and an oscillation signal supplied from a local oscillator to create a signal of an intermediate frequency; a second frequency mixer that mixes the signal of an intermediate frequency and one or more oscillation signals that have an offset added to have different frequency channels, which have a predetermined bandwidth, to create one or more signals of a baseband frequency; a channel selection filter that divides one or more signals generated in the second frequency mixer into one or more different frequency channels having a predetermined bandwidth using the offset; and an amplifier that amplifies the signals that have been filtered in the channel selection filter.

Apparatus for transmitting and receiving signals in radio frequency system

The present invention relates to a direct current (DC) offset suppression circuit to suppress DC offsets occurring when a communication circuit where a complex filter is adopted performs self-mixing. The DC offset is suppressed by a DC feedback circuit adopted by a filter which is substituted for a complex filter in the communication circuit. But, the DC offset cannot be suppressed when a complex filter is used in the communication circuit. It is because phase changes of the complex filter cause output signal fed back to the input of the complex filter to generate phase differences. The present invention includes a phase compensation unit and a DC feedback unit. The phase compensation unit compensates a change in frequency between input and output of the complex filter for phase compensation. The DC feedback unit inverses and feeds back the compensated phase to an input of the complex filter.

DC offset suppression circuit for a complex filter

A low noise reference voltage circuit without using an amplifier inside is capable of transforming a current Iin positive proportion to absolute temperature into a voltage Vin positive proportion to absolute temperature, and outputting it to a ring oscillator. The low noise reference voltage circuit improves a degradation of noise performance compared with a conventional band-gap reference voltage circuit and is in characteristic of low noise and higher PSRR.

Growing community of inventors

Seongnam-si, South Korea

Myung-Woon Hwang