Abstract:
PURPOSE: A digital predistortion method, a system, and a computer-readable recording medium for compensating nonlinear power amplifier which receives OFDM(Orthogonal Frequency Division Multiplexing) signal are provided to obtain the degree of frequency dependent phase shift of the OFDM input signal by using the AM-PM distortion of the power amplifier. CONSTITUTION: A power amplifier feature acquisition unit(210) obtains the frequency dependent phase shift degree of OFDM input signal frequency band by the AM-PM distortion feature of a power amplifier. By the obtained phase shift degree, a first compensation unit(220) compensates phase shift about a complex signal corresponding to one of sub input signal carrier frequencies. A second compensation unit(230) compensates the distorted wave length and phase of the output signal which is converted by the degree of the input signal about the compensated signal.
Abstract:
본 발명은 출력채널수가 감소된 다채널 검출기에 관한 것으로서 입력 신호를 선형으로 증폭하는 선형 증폭기, 선형 증폭기에 독립적인 회로로 구성되며, 내부에 연산 증폭기를 포함하고, 연산 증폭기의 증폭율에 따라 달라지는 오프셋 수준을 보정하는 오프셋 보정부, 선형 증폭기의 출력 신호의 이득을 미세하게 조절하여 입력신호의 불균일 특성을 저하시키는 균일도 보정부, 비교부 및 신호 판별부로부터 출력신호가 발생하고, 스위치 회로가 신호 판별부로부터 트리거를 받는 시점까지 균일도 보정부의 출력 신호를 지연하는 신호 지연기, 균일도 보정부의 출력 신호를 일정 레벨의 신호와 비교하는 비교부, 비교부로부터 트리거 신호를 수신하여, 이벤트가 발생한 채널인 채널 위치 정보를 판별하고, 판별된 채널위치의 스위치 회로에 트리거 신호� � 전송하며, 판별된 위치정보를 출력하는 신호 판별부, 및 신호 판별부로부터 판별된 채널위치의 스위치 회로에 트리거 신호가 입력되면, 에너지 정보, 시간 정보, 또는 이벤트가 발생한 채널 위치 정보를 입력받는 채널 정보 처리부를 포함하는 것을 특징으로 하며, 이벤트가 일어난 채널 위치 정보와 에너지 정보뿐만 아니라, 클럭 발생기와 신호 판별 회로를 추가로 사용하여 시간정보까지 제공할 수 있다.
Abstract:
PURPOSE: A PET device and a signal process method of the PET device are provided to improve the sensitivity of a PET device by increasing a counting rate. CONSTITUTION: A PET device comprises a pre-amplification unit(220), an ADC(Analog to Digital Converter, 230) and a signal processing unit(240). The pre-amplification unit receives a detected gamma-ray signal and amplifies the rise time of the output waveform under 100ns. The ADC changes the signal, amplified by pre-amplification unit, into digital signal. The signal processing unit receives the digital signal and stores the signal having the energy value, in which the photoelectric effect generates.
Abstract:
PURPOSE: A RF oscillator is provided to simplify the design of a load network with optimally maintaining load impedance on a transistor. CONSTITUTION: A RF oscillator (300) comprises a transistor (T), a load network (30), a feedback network (32), and a resonance circuit (34). The resonance circuit receives oscillation signals, and generates resonance signals in basic frequencies. The feedback network is connected to the resonance circuit in series, and feedbacks the resonance signals. The transistor receives the resonance signals, and generates the oscillation signals. The load network receives the oscillation signals, and maintains optimum impedance in high and low frequencies. The resonance circuit operates the load network as an open circuit, and comprises a first capacitor and a first inductor which are connected to each other in series. The optimum impedance is obtained by a harmonic load-full simulation. [Reference numerals] (30) Load network
Abstract:
PURPOSE: An RF(Radio Frequency) power amplifier capable of using a laminate transistor is provided to maintain the drain source voltage of each transistor constantly in spite of the increase of an input power and to improve the linearity of the power amplifier. CONSTITUTION: A circuit using a laminate transistor comprises a plurality of transistors(110,120,130), a plurality of resistors(210,220,230), a plurality of capacitors(310,320) and a diode(400). A plurality of transistors is connected in serial and a source of a second transistor(120) is connected to a drain of a first transistor(110). The drain of the second transistor is connected to the source of the third transistor(130), the source of the first transistor is earthed, and the drain of the third transistor is connected to an output terminal. A gate of the plurality of transistors is connected through the gate of the adjacent transistor which is connected in serial and resistors(220,230) components, and the gate of the first transistor is earthed through some of the resistor(210) components. The capacitor distributes the voltage appropriately to maintain the voltage swing between the gate source and the gate drain within the collapse voltage. The diode maintains the drain voltage of a plurality of transistors constantly even if the input power in which is inputted when the power amplifier operates increases.