Abstract: An amplifier circuit apparatus for driving a laser device, the apparatus comprising a multistage amplifier including an output stage, wherein at least one device for band limiting a signal is coupled to the multistage amplifier prior to the output stage.

Abstract: An inter-stage matching circuit 26 comprises a one-stage high pass filter type matching unit 28 and a one-stage low pass filter type matching unit 29 serially connected with each other.

Abstract: A power amplifier circuit includes a power amplifier responsive to a power mode signal, the power amplifier having a power amplifier output node, and a power amplifier load circuit also responsive to the power mode signal, the power amplifier load circuit having a load circuit input node connected to the power amplifier output node. The power amplifier load circuit has a first transmission line coupled between the load circuit input node and a first node, a harmonic filter coupled between the load circuit input node and a common node, a first capacitor coupled between the first node and the common node, and a first switch coupled between the common node and ground, where the first switch is responsive to the power mode signal.

Abstract: A resonance circuit of a transmission line and a capacitor is connected to the base circuit of a transistor. The transmission line is shorter than one-quarter wavelength to make the resonant frequency of the resonant circuit higher than the frequency of a second harmonic. As a result, the angle of the reflection coefficient of the second harmonic when an input matching circuit side is viewed from the input terminal of the transistor ranges from 170° to 270° on a polar chart, and phase difference between the fundamental wave of the base current and the second harmonic decreases.

Abstract: A differential amplifier and a method for amplifying an input signal are disclosed. The differential amplifier comprises an amplification stage configured to amplify an input signal to produce an amplified output, a current source configured to provide a bias current for the amplification stage, and an impedance network connected to the amplification stage and the current source. The impedance network is configured to provide a high common mode impedance within the range of operating frequencies.

Abstract: A high frequency power amplifier that can improve efficiency of an operation of a transistor without limiting any input-side higher harmonic load of an impedance matching circuit to a short-circuit load, and can increase reflection of higher harmonics. By adjusting line lengths and line widths of signal lines, a 2nd harmonic can be adjusted to be an open load (a reflected phase angle of &Ggr;in: 0-90°, the quantity of reflection: 0.6-1.0), and a 3rd harmonic is adjusted to be a short-circuit load (the reflected phase angle of &Ggr;in: 110-270°, the quantity of reflection: 0.6-1.0). With this input-side higher harmonic load of the impedance matching circuit, efficiency of transistor operation can be improved. By disposing a higher harmonic processing circuit closer to a transistor, a high frequency power amplifier with a shortened line length between the higher harmonic processing circuit and the transistor, and increased quantity of reflection of higher harmonics is produced.

Abstract: An amplifier chain with sequential DC offset correction for use in a radio receiver is provided. The amplifier chain has at least first and second amplifier stages connected in series. The first and second stages include an amplifier and a track and hold circuit connected in parallel across the amplifier. The track and hold circuit has a tracking state and a holding state. A control signal is coupled to the track and hold circuits of the first and second stages. The control signal is configured to set the track and hold circuits to the tracking state, which may be done simultaneously, and to sequentially set the track and hold circuit of the first stage to the holding state and then set the track and hold circuit of the second stage to the holding state.

Abstract: Acoustic resonators such as surface acoustic wave (SAW) devices and thin film bulk acoustic resonators (FBAR) can be configured to produce a band reject filter. Such a filter overcomes the insertion loss and power handling limitations of conventional band pass configurations and as such can be used in power amplifier and duplexer applications.

Abstract: A method and apparatus is disclosed for providing highly linear resistance with high sheet values, and for implementing resistors in a conventional CMOS process when either drain or source must operate near the rail of a circuit. Accordingly, a five terminal distributed MOS resistor device includes a drain terminal, a source terminal, and a channel region disposed between the drain terminal and the source terminal. A bulk terminal is adjacent the channel region. A first gate terminal is adjacent the source terminal and a second gate terminal is adjacent the drain terminal. Lastly, a gate region of resistive material is disposed between the first gate terminal and the second gate terminal, wherein upon application of a voltage to the first gate terminal and the second gate terminal, a voltage drop across the gate region is equally distributed along a length of an electrical channel in the channel region.

Abstract: In a parallel multistage band-pass filter, a transmission line having an electrical length substantially equal to half (&lgr;/2) of the wavelength of the transmission signal is incorporated between the port on the input terminal side of the odd number (2n−1)th resonator numbered from the input terminal side and the port on the input terminal side of the even number (2n)th resonator numbered from the input terminal side; and a transmission line having an electrical length substantially equal to &lgr;/2 is incorporated between the port on the output terminal side of the even number (2n)th resonator numbered from the input terminal side and the port on the output terminal side of the odd number (2n+1)th resonator numbered from the input terminal side. Moreover, a transmission line for adjustment of a transmission phase between the input terminal and the output terminal is incorporated between the first resonator numbered from the output terminal side and the output terminal.

Abstract: A bias circuit is provided for attenuating harmonic distortions of a signal having a simple construction and which can be applied to a high-frequency amplifier used in a communication device, such as a mobile telephone. The circuit reduces a voltage drop therein and thus provides a high-frequency amplifier having reduced power consumption and an increased operating efficiency. The high-frequency amplifier includes an amplifier circuit, an output matching circuit, and the bias circuit. In the bias circuit, a parallel circuit including a first transmission line and a first capacitor has one end connected between the amplifier and the output matching circuit. The other end of the parallel circuit is connected to a power source and is grounded via a second capacitor. In the circuit, the bias circuit can be short-circuited in a desired frequency band while being an open circuit in a frequency band of a signal to be amplified, hence attenuating the harmonic distortions without using a low pass filter.

Abstract: A distributed amplifier consistent with certain embodiments of the present invention has a plurality of amplifier sections 1 through N (302, 306) with each amplifier section having an input and an output. A plurality of N input transmission line sections are connected in series, with inputs of the 1 through N amplifier sections interconnected at their inputs along the series of input transmission line sections. A plurality of N output transmission line sections are also connected in series, with outputs of the 1 through N amplifier sections interconnected at their outputs along the series of input transmission line sections. A load (160) can be driven by an output at the Nth amplifier section (108). A high-pass filter (310) connects a dummy load (150) to the output of the first amplifier section (302). The input and output transmission line sections can, for example, be lumped element T sections and the high-pass filter can be made of a lumped element half section.

Abstract: Second-order harmonic tuning of an active device, such as a transistor used in a radio frequency (RF) power amplifier circuit, is accomplished by positioning a quarter-wavelength stub along a transmission line coupled to an output of the device, such that the output is presented with a desired impedance for the second harmonic.

Abstract: A micro-wave power amplifier which amplifies a micro-wave signal including a plurality of carrier frequencies different from one another, includes (a) a field effect transistor having a grounded source, (b) a first difference frequency circuit which is electrically connected to a drain of the field effect transistor, and is short-circuited at a difference frequency between the carrier frequencies, and (c) a second difference frequency circuit which is electrically connected to a gate of the field effect transistor, and is short-circuited at a difference frequency between the carrier frequencies.

Abstract: A circuit for tuning a transconductance amplifier includes a first transconductance amplifier outputting a first current from its output, a second transconductance amplifier outputting a second current from an output that is coupled to the output of the first transconductance amplifier, and a feedback loop. The feedback loop provides a control signal that varies with a difference between the first current and the second current and is used to adjust the transconductance of the second transconductance amplifier.

Abstract: In a multi-stage amplifier comprising an output stage, the driving of complex loads, such as laser diodes, results in the generation of Electromagnetic Interference (EMI) by current flowing through the complex load. Regulation of this EMI can be difficult. Protection from Electrostatic Discharge (ESD) is also required. A prior technique to protect against ESD employs ESD diodes. However, this solution does not provide EMI regulation and the use of ESD diodes is not an effective measure to protect against ESD when ESD events are too fast for the ESD diodes. The present invention provides ESD protection and EMI regulation by regulating edges of drive signals prior the output stage (300) of the multi-stage amplifier (200).

Abstract: The present invention provides a slope equalizer for use in a voice frequency channel card, which is preferably electronically and remotely controllable, and retrocompatible with existing telecommunication systems. The slope equalizer of the invention includes a high-pass filter followed by a variable gain stage amplifier, where the variable gain stage amplifier is an operational amplifier with a plurality of parallel input signal paths, each of the signal paths being a series-connected resistor and switch. The switch is preferably a FET transistor that is electronically and, optionally, remotely controllable. The circuit topology allows the use of FET transistors having relatively high on-resistances. A further advantage of the topology is that the FET switches are connected to a virtual ground by way of an operational amplifier, thereby reducing on-resistance modulation caused by signal variations across the FET.

Abstract: Systems and methods for increasing the efficiency of direct current (DC) power to radio frequency (RF) power include a harmonic matching network that inhibits harmonic current flow for a number of harmonic frequencies. The matching network includes a number of sections, where each section generates an impedance that resonates with the output capacitance at a harmonic frequency. Each section of the matching network also creates a high impedance to the amplifier at the respective odd harmonic frequency.

Abstract: A high frequency power amplifier is provided that prevents loop oscillation at a low frequency caused by a closed loop formed between combined semiconductor devices. Previously, coupled-line directional couplers or capacitors for low frequency rejection have been used to prevent the closed loop from being formed. Also, a circuit including a resistance component required for attenuating self-oscillation has been provided. Therefore, to prevent both loop oscillation and self oscillation, two circuits have been required. Accordingly, a high frequency power amplifier is provided with a low frequency prevention circuit that attenuates the passing of each frequency of loop oscillation and self oscillation to each signal line divided by a power divider. Thus, the two circuits respectively required for preventing the loop oscillation and self oscillation of a travelling wave combine type amplifier can be formed by one low frequency prevention circuit.

Abstract: In order to decrease a change in the offset caused by high-frequency noise, filter circuits for cutting high-frequency noise are inserted between the input terminals of a differential amplifier circuit and input nodes of a differential amplifier stage, the filter circuits having a cut-off frequency which is higher than a cut-off frequency of the differential amplifier circuit but is lower than a cut-off frequency of a parasitic filter circuit constituted by a parasitic capacity and a parasitic resistance in the input unit.

Abstract: A feedforward amplifier and notch filter (150) according to the present invention uses a direct coupling of an amplifier stage (158) with the amplifier's load (RL). The main amplifier (202) is coupled through a transmission line (210) to the load. This direct coupled amplifier stage (158) is driven by an signal that induces a very low impedance in parallel with the load at the receive frequency, but appears as an open circuit at the desired frequencies so that the desired signal from the main amplifier is virtually unaffected while output components at the receive frequency are cancelled.

Abstract: A current mirror circuit incorporates a resistor-capacitor (RC) filter circuit in the base-coupling path of input and output current mirror transistors, to realize a highly integrated low pass filter current mirror architecture, that reduces implementation complexity, and complies with reduced power supply parameters of a subscriber line interface circuit. A filter resistor is connected in series between the bases of the input and output current mirror transistors. A filter capacitor is coupled between the base of the output transistor and the power supply rail. The effect of this low pass filter circuit is such that the output current is equal to the frequency content of the input current below the cut-off frequency as defined by the RC time constant of the filter.

Abstract: A radio frequency power amplifier module for a dual-band type mobile communication apparatus that can transmit and receive a first frequency f1 and second frequency f2 (f2=2×f1). It includes a drive stage amplifier having the gain peaks at f1 and f2 with a matching circuit and a radio frequency power output circuit including a radio frequency power output transistor. The output circuit has a transmission line connected to the drain end of the output transistor, a parallel resonance circuit connected in series to the transmission line to resonate at harmonics of a frequency twice the frequency f2, a series resonance circuit provided between one end of the resonance circuit and the ground to resonate at harmonics of a frequency twice the frequency f2 and an output matching circuit provided in series to the other end of the parallel resonance circuit for matching with f1 and f2.

Abstract: A apparatus for providing a waveform as a switched input into an output matching network of a standard class E amplifier. The apparatus includes a switch in communication with the input and the combining device receiving amplitude and phase information from the primary waveform. The combining device functions to combine the amplitude and phase information to create a control signal which is used to control the switch and create a secondary waveform for input to the matching network. In this way, an amplitude modulated waveform is amplified at high efficiency, enabling application of either all or part of the phase and/or amplitude modulation at the input of the amplifier.

Abstract: An electrically tunable radio frequency (RF) amplifier includes a resonant circuit having a voltage variable capacitance as one of its elements. In one approach, a drain diffusion capacitance of one of the transistors within the amplifier is used as the voltage variable capacitance. A voltage adjustment unit is provided to adjust a bias voltage on the voltage variable capacitance to change the capacitance value thereof and thus modify the operating frequency range of the amplifier. In one embodiment, the voltage adjustment unit also provides a power supply noise blocking function.

Abstract: Low pass filters at the output stage of a D-class amplifier, in which a high channel separation between adjacent signal amplifying channels, a small size, implementation at a high density can be attained. Induced electromotive forces by a leakage magnetic flux from the adjacent channels are set off by a plurality of pairs of inductors in one low pass filter. The low pass filter of each channel is formed by the same construction and the same circuit. The inductors are arranged in a manner that center axes of coils of the two corresponding pairs of inductors in the adjacent channels are located at vertexes of a rectangular parallelogram, and combinations of the winding directions of the coils of the corresponding inductors of the adjacent channels are set to the same direction and the opposite directions every other inductor.

Abstract: A linear amplifier using a low frequency 2nd intermodulation feed-forwarding method to offset the 3rd intermodulation component of a fundamental signal is provided. This linear amplifier includes a transistor for amplifying the power of the fundamental signal, a first filter unit, one end of which is connected to the gate of the transistor, for filtering a 2nd order intermodulation signal from the fundamental signal, a low frequency amplifier connected to the other end of the first filter unit, for amplifying the 2nd order intermodulation signal with a predetermined voltage gain, and a second filter unit connected in series between the output port of the low frequency amplifier and the drain output port of the transistor, for filtering the amplified 2nd intermodulation signal and feeding the same to the output port of the transistor.

Abstract: A band pass filter includes a pair of filters having different center frequencies and a difference amplifier coupled to the outputs of the filters. The filters preferably have response curves that intersect at −3 dB. The separation of the center frequencies determines, in part, the ripple in the response curve of the band pass filter.

Abstract: The present invention describes the method and system of applying filter synthesis technique to distributed amplifier design. The method for synthesizing a distributed amplifier comprises the steps of determining an appropriate filter design characteristic, computing inductor and capacitor values, converting the equivalent values into a distributed amplifier with response characteristics that mirror that of the chosen filter. Applying filter synthesis techniques to distributed amplifier design results in predictable amplifier response characteristics. Filter synthesis techniques are used to design filters with controllable characteristics such as gain, cut-off frequency, and roll-off slope. Depending on the desired filter characteristics, appropriate inductor and capacitor sizes can be determined. Transferring these chosen inductors and capacitors sizes to the distributed amplifier results in amplitude and phase responses that behave like a preferred embodiment or prototype filter.

Abstract: Receive band filtering between the last two stages of an N-stage power amplifier can reduce the Rx band noise. There are N−1 interstage matching networks interposing N stage amplifiers, where N≧2. The interstage matching networks and stage amplifiers are electrically connected in series. The N−1th interstage matching network includes a receive band reject filter positioned proximate to the output of the N−1th stage power amplifier.

Abstract: An amplifier circuit for amplifying an input signal to generate an amplifier output signal incorporates a cascaded series of reflection amplifiers arranged along a signal path and operative to amplify signals propagating in a forward direction along the signal path. The circuit is operative to counteract signal propagation in a reverse direction along the signal path, thereby hindering spontaneous oscillation from arising within the circuit. Incorporation of reflection amplifiers into the circuit enables it to provide high gain, for example 50 dB, while consuming low currents, for example, tens of microamperes. The circuit is especially suitable for use at intermediate frequencies in radio receivers such as mobile telephones.

Abstract: A T-type circuit having series resistors and a parallel resistor is arranged on the outside of an amplifier, a signal is amplified in the amplifier while stabilizing the signal by using the T-type circuit functioning as a stabilizing circuit, and the amplified signal is output. In this case, values of the series resistors and the parallel resistor of the T-type circuit are determined so as to set an output load impedance obtained by seeing the output side of the high-frequency amplifier from the amplifier to a value near to or slightly lower than a value of the conjugate complex impedance of an output impedance of the amplifier. Therefore, the output signal having a high output electric power and a low distortion can be obtained in the high-frequency amplifier while keeping a gain and a noise characteristic of the high-frequency amplifier.

Abstract: An impedance matched frequency dependent gain compensation network for multi-octave passband equalization. A first stage amplifier outputs an amplified signal to an equalizer, which in turn outputs an equalized signal to a second stage amplifier. The equalizer varies the attenuation in accordance with the frequency to provide minimum gain variation, thereby providing optimal noise characteristics and generally constant linearity.

Abstract: Systems and methods for increasing the efficiency of direct current (DC) power to radio frequency (RF) power include a harmonic matching network that inhibits harmonic current flow for a number of harmonic frequencies. The matching network includes a number of sections, where each section generates an impedance that resonates with the output capacitance at a harmonic frequency. Each section of the matching network also creates a high impedance to the amplifier at the respective odd harmonic frequency.

Abstract: The amplification element is configured by amplifying a multicarrier signal by combining plural carrier waves modulated independently There is disclosed a high-frequency amplifier for amplifying multicarrier signals generated by combining plural carrier waves modulated independently. The amplifier performs a predetermined filtering processing at its output end. An amplification element is also disclosed which is integrated with a circuit for suppressing main components of nonlinear distortions, thus forming an integrated circuit. In electronic appliances, equipments, or systems to which the invention is applied, achievement of reduction in price and size, improvement in reliability, and maintenance and operation being done more efficiently at reduced costs can be accomplished.

Abstract: A radio frequency power amplifier module for a dual-band type mobile communication apparatus that can transmit and receive the first frequency f1 and the second frequency f2 (f2=2×f1) is structured as explained below. This radio frequency power amplifier module for dual-band type mobile communication apparatus is comprised of a drive stage amplifier having the gain peaks at f1 and f2 with a matching circuit and a radio frequency power output circuit including a radio frequency power output transistor.

Abstract: An integrated circuit (IC) differential amplifier is disclosed. The differential amplifier comprises two amplifier stages each containing a transistor amplifier stage connected to one of the inputs of a push-pull input (RFin, RFXin) and a cascode stage connected to one of the outputs of a push-pull output (RFout, RFXout), where the cascode stages can be switched by a changeover switch (DC gain switch).

Abstract: A variable bandpass filter system passes a selected range of frequencies while rejecting other frequencies in an RF input signal. The system includes a switch and an oscillator. The switch receives the RF input signal and an oscillating calibration signal, and passes the RF input signal or said oscillating calibration signal based on a control signal. The oscillator receives an output of the switch, and frequency and gain control signals. The frequency control signal selects an operating frequency of the oscillator, such that the operating frequency determines a range of frequencies to pass. The gain control signal selects gain of the oscillator, where the oscillating calibration signal allows the oscillator to be calibrated by varying the gain such that the oscillator acts as a filter.

Abstract: A microwave amplifier includes a bias circuit including a micro-strip line and a capacitor for biasing an output line of a FET with a DC voltage, and a filter block implemented by a low-pass-filter or a band-rejection-filter and a capacitor serially connected between the output line and the ground. The filter block passes a beat frequency generated by two of the carrier signals included in the input signal of the FET while maintaining the carrier signals on the output line.

Abstract: A microwave amplifier includes a bias circuit including a micro-strip line and a capacitor for biasing an output line of a FET with a DC voltage, and a filter block implemented by a low-pass-filter or a band-rejection-filter and a capacitor serially connected between the output line and the ground. The filter block passes a beat frequency generated by two of the carrier signals included in the input signal of the FET while maintaining the carrier signals on the output line.

Abstract: The invention provides a high frequency power amplifier that prevents loop oscillation at a low frequency which is caused by a closed loop formed between combined semiconductor devices in case plural power combine circuits are used for tournament connection. Heretofore, for a countermeasure for the loop oscillation, a coupled-line directional coupler is used or a capacitor for low frequency rejection to prevent a closed loop from being formed is inserted into each signal line and a bias circuit is provided separately. Also, as a semiconductor device causes self oscillation by impedance applied to the input and output, a circuit including a resistance component required for attenuating an oscillated signal is provided. Therefore, to prevent both loop oscillation and self oscillation, two circuits are required.

Abstract: A radio-frequency amplifier including a power amplifier for amplifying the power of a radio-frequency signal in a desired frequency band; and a band rejection filter for receiving the radio-frequency signal from the power amplifier and for restricting the spread of the signal spectrum into frequency bands which lie adjacent to the desired band of the radio-frequency signal. The band rejection filter includes a first line, which is formed of a non-superconducting material and which receives a radio-frequency signal, and a second line, used for resonance, which is formed of a superconducting material and which resonates with adjacent frequencies. Because the thus arranged superconducting filter is employed, a radio-frequency signal is transmitted at a high power along the first line, while a radio-frequency signal in an adjacent frequency band, for which the power is comparatively low and is to be removed, is suppressed along the second line, which is formed of a superconducting material.

Abstract: A semiconductor integrated circuit device comprises a multiple-stage amplifier including a plurality of transistors. The multiple-stage amplifier has a first stage comprising a plurality of bipolar transistors each having a single emitter structure. The bipolar transistors are connected parallel to each other. The semiconductor integrated circuit device can easily be designed, is of a self-aligned structure, and has a single transistor size. The semiconductor integrated circuit device may be used as a low-noise, high-power-gain high-frequency amplifier.

Abstract: A signal amplification system involves transforming at least one signal to be amplified into at least one transformed signal which is amplified and the resulting amplified transformed signal(s) can be used to produce a version(s) of the at least one original signal. The at least one transformed signal can be produced from the at least one original signal by using the at least one original signal to amplitude and/or angle (phase or frequency) modulate the at least one original signal. After amplification of the at least one transformed signal, the resulting at least one amplified transformed signal is de-modulated to produce a version(s) of the at least one signal. In transforming the at least one original signal to produce the at least one transformed signal, the at least one original signal is transformed into a more desirable form, such as a more power efficient form, for amplification.

Abstract: In order to decrease a change in the offset caused by high-frequency noise, filter circuits for cutting high-frequency noise are inserted between the input terminals of a differential amplifier circuit and input nodes of a differential amplifier stage, the filter circuits having a cut-off frequency which is higher than a cut-off frequency of the differential amplifier circuit but is lower than a cut-off frequency of a parasitic filter circuit constituted by a parasitic capacity and a parasitic resistance in the input unit.

Abstract: An amplifier stage having a first and a second transistor connected in series to each other between a first and a second reference potential line. The first transistor has a control terminal connected to an input of the amplifier stage through a first inductor, a first terminal connected to the second reference potential line through a second inductor, and a third terminal connected to a first terminal of the second transistor. The second transistor has a second terminal forming an output of the amplifier stage, and connected to the first reference potential line through a load resistor. To improve the noise figure, a matching capacitor is connected between the control terminal and the first terminal of the first transistor.

Abstract: A band pass filter includes a pair of notch filters having different notch frequencies and a difference amplifier coupled to the outputs of the notch filters. The notch filters preferably have response curves that intersect at −3 dB. The separation of the notch frequencies determines, in part, the ripple in the response curve of the band pass filter.

Abstract: A circuit is designed with a first transconductor circuit (903) with a first input terminal (901) coupled to receive a voltage signal, a second input terminal (1017) coupled to receive a control signal and an output terminal. The first transconductor circuit has a gain responsive to the control signal. A first integrator circuit (905) has an input terminal coupled to the first transconductor circuit output terminal and has an output terminal. A second transconductor circuit (909) has an input terminal coupled to the first integrator circuit output terminal and an output terminal. A second integrator circuit (911) has an input terminal coupled to the second transconductor circuit output terminal and has an output terminal.

Abstract: An inventive FET balun transformer uses a positive power supply alone, not a negative one, thus downsizing a device including the balun transformer. In the FET balun transformer, a voltage supplied from the positive power supply is divided by a voltage divider consisting of a pair of resistors. The gate of a first FET is biased at a positive voltage, which is obtained by getting the divided supply voltage further divided by a first resistor. The gate of a second FET is grounded with an AC grounded capacitor interposed therebetween and biased at a positive voltage, which is obtained by getting the divided supply voltage further divided by a second resistor. Thus, the gate and source of a third FET do not have to be set at a negative potential, but may be grounded directly and via a biasing resistor, respectively.

Abstract: A high efficiency dual-band RF power amplifier has an output and/or input of a high frequency transistor well terminated at the second harmonic frequency for dual-band operation. Diode switches or voltage controlled varactors implement dual-band resonators such that they can offer low impedance at the second harmonic of each frequency band, while, in some cases, presenting high impedance at the fundamental frequency as an RF choke circuit.