Abstract: A quasi-differential amplifier with an input port and an output port. The amplifier has a phase shifter network with a first port connected to the input port, a second port, and a third port. A first amplifier has an input connected to the second port of the phase shifter network, and an output, and a second amplifier has an input connected to the third port of the phase shifter network, and an output. A balun circuit includes a first differential port connected to an output of the first amplifier, a second differential port connected to an output of the second amplifier, and a single-ended port. An output matching network is connected to the single-ended port of the balun circuit and to the output port.
Abstract: An apparatus includes a first amplifier having a first feedback resistance and an output configured to be coupled to a first input of a second amplifier having a second feedback resistance. The apparatus includes a third amplifier coupled to an input of the first amplifier and having an output configured to be coupled to a second input of the second amplifier.
Abstract: A power amplifier according to the present invention includes: an apparatus housing (10) having a hole (11) for maintenance formed therein; a transmission line unit (12) disposed in a location covered by the apparatus housing (10), a transmission line length of the transmission line unit being adjusted depending on a frequency band of an input signal; and an element (13) that requires no adjustment of a transmission line even when an adjustment of the transmission line unit (12) is required along with a change in the frequency band of the input signal. The transmission line unit (12) is disposed near a surface of an apparatus that is accessible from outside through the hole (11) for maintenance, and the element (13) that requires no adjustment of the transmission line is buried in a location within the apparatus housing that is inaccessible through the hole for maintenance (11).
Abstract: An amplifier device includes an initial amplifier stage configured to receive a differential input signal at a first leg and a second leg; a final amplifier stage coupled to outputs of the initial amplifier stage, the final amplifier stage including a primary signal amplifier and an error amplifier in each of the first and second legs; and wherein an output of the error amplifier of the first leg is combined with an output of the primary signal amplifier in the second leg, and an output of the error amplifier of the second leg is combined with an output of the primary signal amplifier in the first leg.
Abstract: A power amplifier unit for a magnetic resonance device includes at least two power amplifier modules. Symmetrical output signals from the at least two power amplifier modules are fed to a shared balun. The shared balun is provided on a printed circuit board (PCB) and is realized in a unit with the at least two power amplifier modules. The balun is configured to asymmetrize a sum signal.
July 22, 2011
July 26, 2012
Adam Albrecht, Horst Kröckel, Markus Vester
Abstract: A power amplifier includes an amplifying circuit, and first through third transmission lines. The amplifying circuit amplifies an input signal having a fundamental frequency to generate a first amplified signal and a second amplified signal whose phase is opposed to the first amplified signal. The first transmission line adds a first group of phases, different in correspondence with a frequency, to the first amplified signal by using a left-handed material to generate a first transmission signal. The second transmission line adds a second group of phases, different in correspondence with a frequency, to the second amplified signal by using a right-handed material to generate a second transmission signal. The third transmission line overlaps the first and the second transmission signals to generate an output signal. The first and the second group of phases include a phase difference configured to weaken a second harmonic and a third harmonic.
Abstract: A low noise amplifier (LNA) with combined input matching, balun, and/or transmit/receive (T/R) switch is described. In one exemplary design, an apparatus includes a coupled inductor and an LNA. The coupled inductor receives a single-ended input signal, performs single-ended to differential conversion, and provides a differential input signal. The LNA receives and amplifies the differential input signal and provides a differential output signal. The coupled inductor includes magnetically coupled first and second coils. The first coil provides input impedance matching when the LNA is enabled. A resonator circuit formed with the first coil provides high input impedance when the LNA is disabled. A tuning capacitor coupled to the second coil provides amplitude imbalance tuning for the differential input signal. A transmit switch is coupled between the first coil and a transmitter.
Abstract: A calibration unit calibrates a power amplifier load impedance to achieve a nominal amplifier load impedance after the connection of one or more external elements, e.g., antenna, to improve the accuracy and effectiveness of output power calibration. The calibration unit comprises an adaptive impedance unit and a controller. The adaptive impedance unit includes first and second variable impedance elements connected between the amplifier and the external load, e.g., antenna. The controller independently calibrates the imaginary and real parts of the load impedance by respectively selecting first and second calibration values for the first and second variable impedance elements based on a reference voltage. More particularly, the controller selects calibration values for the first and second variable impedance elements from a plurality of impedance values based on a comparison between a reference voltage and the calibrated voltages produced at the output of the power amplifier responsive to the impedance values.
December 30, 2010
March 29, 2012
Hendrik Visser, Roeland Heijna, Norbert Van Den Bos
Abstract: Systems and methods are provided for a transformer or balun function with reference enhancement. The systems and methods may include a transformer having at least a primary winding and a secondary winding for reference enhancement, where the primary winding includes a center tap, where the secondary winding includes a first port and a second port, and an electrical connection that electrically connects the second port and the center tap of the primary winding to provide a common reference for the primary winding and the secondary winding. The primary winding of the transformer may be configured to receive differential outputs of a power amplifier, and the transformer may be configured to convert the differential outputs from a balanced signal to an unbalanced signal available at the first port of the secondary winding.
Abstract: An amplifier circuit includes a pair of amplifying devices, a first balun coupled between an input port of the amplifier circuit and RF input ports of the pair of amplifying devices and a second balun coupled between RF output ports of the pair of amplifying devices and an output port of the amplifier circuit wherein the first and second baluns are configured such that the amplifier circuit operates under open condition for signals at a second harmonic frequency even when the second harmonic frequency is within an operating frequency band of a fundamental frequency of the amplifier circuit. In one embodiment, the amplifier circuit includes a bypass circuit which selectively couples balun ports to ground such that in response to a first control signal, the amplifier circuit operates in an amplifying mode and in response to a second control signal, the amplifier circuit operates in a bypass mode.
Abstract: A differential to single ended converting circuit includes a transconductance circuit having input terminals for receiving differential input voltages and having a first current output terminal for outputting a first current and a second current output terminal for outputting a second current; an offset cancellation circuit having a first controllable current source connected to the first current output terminal and a second controllable current source connected to the second current output terminal; a first transimpedance circuit having an input terminal connected to the first current output terminal and an output terminal for outputting a first voltage; a second transimpedance circuit having an input terminal connected to the second current output terminal and an output terminal for outputting a second voltage; and a first inverter having an input terminal connected to the output terminal of the first transimpedance circuit and an output terminal for outputting a first single ended output voltage.
Abstract: The present invention relates to a variable gain amplifier. The variable gain amplifier includes an input unit including first and second input nodes and an output node, the input unit being configured to receive first and second input signals. The variable gain amplifier further includes a first clipping unit operable to clip a voltage level at the output node to be equal to or lower than a level of a first reference voltage and a second clipping unit operable to clip a voltage level at the output node to be equal to or greater than a level of a second reference voltage, wherein the second reference voltage is lower than the first reference voltage. A predetermined level of a voltage is outputted through an output unit included in the variable gain amplifier based on the clipped voltage level.
Abstract: Device, system, and method of low-noise amplifier. For example, an apparatus includes a low-noise amplifier to convert a single-ended wireless communication signal into a corresponding differential signal.
Abstract: A transceiver front end includes a transmit/receive (T/R) switch, a first balun, a second balun, a low noise amplifier, a power amplifier, and compensation circuitry. The T/R switch is operably coupled to an antenna for receiving inbound radio frequency (RF) signals and for transmitting outbound RF signals. The first balun includes a single ended winding and a differential winding, where the single ended winding is operably coupled to the T/R switch. The second balun includes a single ended winding and a differential winding, where the single ended winding is operably coupled to the T/R switch. The low noise amplifier is operably coupled the differential winding of the first balun. The power amplifier is operably coupled to the differential winding of the second balun. The compensation circuitry is operably coupled to the first balun to compensate for at least one of phase imbalance, amplitude imbalance, and impedance imbalance of the first balun.
May 24, 2004
Date of Patent:
September 11, 2007
Janice Chiu, Shahla Khorram, Qiang (Tom) Li
Abstract: A circuit interfacing a balanced RF power amplifier with unbalanced load has a first shunt inductor and a series capacitor connected to a first output and a first shunt capacitor and series inductor connected to a second output of amplifier. The circuit comprises a second shunt inductor connected to the second output and feeding current to the second output. The first shunt capacitor may correspond to a sum of capacitors required to resonate with the series inductor and second shunt inductor. The second shunt inductor may exceed a value required to resonate with the capacitance of the first shunt capacitor less the capacitance required to resonate with the series inductor, by the same amount as the first shunt inductor exceeds the value required to resonate with the series capacitor. The circuit may further comprise a second shunt capacitor connected to first output, whereby first shunt capacitor exceeds sum of capacitors required to resonate with series inductor and second shunt inductor.
Abstract: A multiplexed audio-video signal transmission system has a camera-equipped intercom which produces a balanced audio-video signal. A twisted pair-wire connected to the intercom transmits a multiplexed signal of audio signal, video signal modulated to a frequency band not overlapping the audio signal frequency, and DC power. The audio signal and video signal are carried in the pair-wire in opposite phase in a balanced condition, and the DC power is carried between the pair-wire. A relay device is inserted in the pair-wire to refine the video signal. Main line branching device and door branching device are provided to branch out the multiplexed signal to a television equipped control unit 17.
April 14, 1994
Date of Patent:
July 7, 1998
Matsushita Electric Industrial Co., Inc.
Abstract: A broadband optical receiver which exhibits low noise and distortion characteristics. An active bias feedback circuit stabilizes the quiescent operating currents of a low noise amplifier coupled to the receiver photodetector. A transformer matches the impedance of the amplifier to an attenuator.
Abstract: A matching circuit is connected between a source circuit and a load circuit. The matching circuit is made up of an impedance transforming circuit and a balance-to-unbalance signal-transforming circuit. If necessary, means for blocking the DC components intervene between those transforming circuits. The impedance transforming circuit is made up of inductive and capacitive elements. The matching circuit is reversible.
Abstract: A correction circuit is provided to improve current accuracy by sensing the error current of a first variable current source and substracting it from the output of a second variable current source. It also increases output impedence by sensing incremental output current and cancelling its effect.
Abstract: An improved transducer amplifier includes a first operational amplifier having low drift of its input offset voltage characteristic and having a first output of a transducer connected to its positive input and a second output of the transducer connected by means of an input resistor to its negative input. The gain of the first operational amplifier is set by a feedback resistor. A second operational amplifier having low current drain is connected as a voltage follower with its input connected to the first transducer output. A differential signal produced between the voltage follower output and the output of the first operational amplifier is applied to a conventional differential to single ended converter circuit with precisely matched input and feedback resistors to eliminate the common mode voltage component of the differential signal and to reference an amplified error signal component of the differential signal to ground.
Abstract: Low level analog signals from remote locations are amplified after being converted into two consecutive analog signals of opposite polarities and a digital system causes A/D conversion to occur in two successive readings corresponding to said polarities and an algebraic combination of the two successive readings in binary form provides a true reading which is made available for digital processing by a special control circuit.