Abstract: The multi-modal imaging system, in particular for brain imaging, comprising a pump signal generator which emits at least one pump signal in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit, which comprises at least one parametric resonator circuit with multiple resonance modes, wherein the at least one parametric resonator circuit comprises at least two varactors, at least one capacitor and at least one inductance, wherein, in a first detection mode, the pump signal, having a first power P1, induces a first pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated below its oscillation threshold and generates a first output signal by amplifying a first input signal, which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device receives the first output signal, wherein, in a second detection mode, the pump signal, having a second power P2, induces a

Abstract: In accordance with an aspect of the present disclosure, there is provided a power amplification apparatus, the apparatus comprising: an input part; a first-1 transformer and a first-2 transformer connected to the input part in parallel; a first amplifier and a second amplifier connected to the first-1 transformer and the first-2 transformer, respectively; a first switch connected to one side of the first-2 transformer; a second-1 transformer and a second-2 transformer connected to the first amplifier and the second amplifier, respectively, and connected to an output part in parallel; and a second switch connected to one side of the second-2 transformer.

Abstract: Systems and methods for suppressing and mitigating harmonic distortion in a circuit are disclosed. In one example, a disclosed circuit includes a radio frequency (RF) oscillator and a power amplifier. The RF oscillator is configured to generate an RF signal. The power amplifier is configured to generate an amplified RF signal based on the RF signal. The power amplifier includes a transformer including a primary winding and a secondary winding, and a feedback capacitor electrically coupled to the primary winding and the secondary winding.

Abstract: An amplifier, comprising: an amplifying element having an input side and an output side; a first transformer on the output side of the amplifying element arranged to mutually couple a fraction of the output current from the amplifying element onto the input side of the amplifying element; a second transformer on the input side of the amplifying element arranged to increase the input voltage on the input side via mutual coupling of its primary and secondary windings; wherein a primary winding of the first transformer is connected to an output of the amplifying element; wherein a secondary winding of the first transformer is ac connected to a secondary winding of the second transformer; and wherein the primary winding of the first transformer is dc blocked from the secondary winding of the second transformer. The negative and the positive reactive feedback loops are not formed from the same trifilar transformer.

Abstract: A power amplifier circuit includes: a first differential amplifier that amplifies a first signal split from the input signal and outputs a second signal; a second differential amplifier that amplifies a third signal split from the input signal and outputs a fourth signal; a first transformer including a first input-side winding to which the second signal is input and a first output-side winding; a second transformer including a second input-side winding to which the fourth signal is input and a second output-side winding; a first phase conversion element that is connected in parallel with the first output-side winding and outputs a fifth signal; and a second phase conversion element that is connected in parallel with the second output-side winding and outputs a sixth signal. The first and second output-side windings are connected in series and output a signal obtained by adding voltages of the fifth and sixth signals together.

Abstract: An apparatus is disclosed that includes a wireless transceiver with reconfigurable transformers. In an example aspect, the wireless transceiver includes an amplifier, a set of transformers, and switch circuitry. The amplifier includes an amplifier input and an amplifier output. The set of transformers includes a first transformer and a second transformer. The first transformer includes a first inductor and a second inductor, and the second transformer also includes a first inductor and a second inductor. The switch circuitry is configured to switchably couple the set of transformers to the amplifier input and the amplifier output of the amplifier.

Abstract: A power amplifier circuit includes: a first differential amplifier that amplifies a first signal split from the input signal and outputs a second signal; a second differential amplifier that amplifies a third signal split from the input signal and outputs a fourth signal; a first transformer including a first input-side winding to which the second signal is input and a first output-side winding; a second transformer including a second input-side winding to which the fourth signal is input and a second output-side winding; a first phase conversion element that is connected in parallel with the first output-side winding and outputs a fifth signal; and a second phase conversion element that is connected in parallel with the second output-side winding and outputs a sixth signal. The first and second output-side windings are connected in series and output a signal obtained by adding voltages of the fifth and sixth signals together.

Abstract: A high frequency amplifier circuit includes a transistor including a drain, a gate, and a source, an inductance-capacitor (LC) tank connected to the drain, and a transformer connected to the gate and the source.

Abstract: A circuit for amplifying a source signal generated by a signal source having a first impedance includes a transmission line transformer (TLT) having a first, a second, a third, and a fourth port wherein the TLT is coupled to receive the source signal at the first port and configured to output a corresponding impedance matched signal at the second port, the second port is coupled to the third port of the TLT, the circuit also including a TLT load having a first terminal coupled to the fourth port of the TLT and a second terminal coupled to a reference potential. The circuit additionally includes an amplifier device responsive to the impedance matched signal to generate an amplified signal.

Abstract: Methods and devices are described for overcoming insertion loss notches in RF systems. In one case programmable impedances are used to move an insertion loss notch outside a frequency band of interest.

Abstract: Differential power amplifier circuitry includes a differential transistor pair, an input transformer, and biasing circuitry. The base contact of each transistor in the differential transistor pair may be coupled to the input transformer through a coupling capacitor. The coupling capacitors may be designed to resonate with the input transformer about a desired frequency range, thereby passing desirable signals to the differential transistor pair while blocking undesirable signals. The biasing circuitry may include a pair of emitter follower transistors, each coupled at the emitter to the base contact of each one of the transistors in the differential transistor pair and adapted to bias the differential transistor pair to maximize efficiency and stability.

Abstract: An audio amplifier is powered by a switch mode power supply optimized for audio applications. The power supply includes a rectifier circuit and a discontinuous mode multiphase isolated flyback power circuit and does not require a separate power factor correction stage. The discontinuous mode multiphase isolated flyback power circuit includes multiple isolated flyback converters operating synchronously to each convert a portion of the power and supply a phase-summed direct current voltage to the audio amplifier.

Abstract: An amplifier includes a transformer including a primary coil whose one end is connected to an input port and whose other end is connected to reference potential and a secondary coil magnetically-coupled with the primary coil, and a transistor including a source connected to one end of the secondary coil and a gate connected to other end of the secondary coil and a drain connected to an output port side.

Abstract: Several multiband transceivers are disclosed. An exemplified multiband transceiver supporting different bands has a transformer, an inbound switch circuit, and an outbound switch circuit. The transformer has input ports on a primary side, and output ports on a secondary side. The input ports are direct-current isolated from and magnetically coupled to the output ports. The inbound switch circuit is configured to connect one of the input ports with an RF signal source for signal transmission. The outbound switch circuit is configured to connect one of the output ports with a RF output load. Optionally, an input tunable capacitor is configured to shunt with the effective inductance of one of the input ports and form a LC tank for band selection.

Abstract: A digital communication system comprising a host and a client, the host calls the client via two transmission lines. The host includes a processor, a first control unit, a second control unit, a high frequency transformer and an interface unit. The digital communication system utilizes the first control unit and the high frequency transformer to modulate outgoing signals. The digital communication system utilizes the second unit and the high frequency transformer to demodulate incoming signals.

Abstract: Disclosed herein is a transformer including: a primary coil formed of a first conductor having a predetermined length and including a first end and second end for receiving a signal, wherein the first conductor is formed as a first loop; and a secondary coil that is coupled to the primary coil in an electromagnetic coupling, and is formed of a second conductor having a predetermined length and including a first end and a second end for outputting a signal, wherein the second conductor is formed as a second loop, wherein the primary coil and the secondary coil are stacked while crossing each other. Accordingly, power transformer efficiency may be increased.

Abstract: An asymmetrical transformer output demultiplexing (ATODEM) circuit is disclosed. The ATODEM circuit of the present disclosure includes N input windings, wherein N is a natural number. Each of the N input windings have input terminals that couple to output terminals of N PAs. The ATODEM further includes M output ports wherein M is a natural number, each of the M output ports having N series coupled windings coupled between a load terminal and a return terminal. The physical attributes of the N input windings, and the N series coupled windings of the M output ports are asymmetrical such that in an Nth operation mode an Nth PA first-load line impedance matches an output impedance of an Nth PA coupled to the input terminals.

Abstract: The present invention provides a high-frequency power amplifying device capable of transmitting output power at high efficiency. For example, a high-frequency power amplifying device has first and second differential amplifiers and a transformer for matching output impedances of the differential amplifiers. Between differential output nodes of the first differential amplifier, an inductor, a switch, and an inductor are coupled in series. When the second differential amplifier is in an operating state and the first differential amplifier is in a non-operating state, the switch is controlled to be on. In this case, due to “off capacitance” in transistors of a differential pair included in the first differential amplifier, impedance on the first differential amplifier side seen from both ends of primary coils becomes a high impedance state (parallel resonance state) and, equivalently, the primary coils do not exert influence on the operation of the second differential amplifier.

Abstract: A method for generating an amplified radio frequency (RF) signal is provided. In-phase (I) and quadrature (Q) signals are received and interleaved so as to generate a time-interleaved signal. Delayed time-interleaved signals are then generated from the time interleaved signal, and each of the delayed time-interleaved signals is amplified so as to generate a plurality of amplified signals. The amplified signals are then combined with a transformer, where the delayed time-interleaved signals are arranged to generate a filter response with the transformer.

Abstract: An upconverter has a two port parametric amplifier that has a first port to receive an input signal to be amplified and upconverted and a second port to receive a local oscillator signal and to output the amplified, upconverted signal at upper and lower sideband frequencies. The upconverter further has an antenna coupled to the second port to receive the local oscillator signal and transmit the amplified, upconverted signal at upper and lower sideband frequencies and a low noise amplifier at the first port of the parametric amplifier, which is powered by the local oscillator signal.

Abstract: A magnetic resonance imaging system upconverter stage has a number of local coils and a number of upconverters to receive a signal from an output of each coil. Each upconverter has a number of two port upconverter cores, each core having a first port to receive a signal from a local coil and a second port to output an upconverted signal at upper and lower sideband frequencies through an antenna coupled to the second port. The inputs of the plurality of upconverter cores are connected in parallel, and at least one antenna is associated with the second port of each core.

Abstract: An upconverter has a two port parametric amplifier that has a first port to receive an input signal to be amplified and upconverted and a second port to receive a local oscillator signal and to output the amplified, upconverted signal at upper and lower sideband frequencies. The upconverter further has an antenna coupled to the second port and a power splitter inserted between the second port of the parametric amplifier and the antenna.

Abstract: A wide bandwidth planar four port MMIC transformer is provided by input diplexers which divide up the incoming signal into a high band and a low band, with the resulting signals coupled to high band and low band four port transformers implemented in one embodiment using spiral inductors and coupled lines, the outputs of which are combined using two output diplexers to provide a decade bandwidth transformer.

Abstract: Traditionally, low-noise amplifiers or LNAs have been used in high frequency applications, but for very high frequency ranges (i.e., 60 GHz), building an LNA to meet performance needs has been difficult. Here, however, an LNA has been provided that operates well around 60 GHz. In particularly, this LNA is generally unconditionally stable, has a generally low noise factor or NF, and has a generally high gain around 60 GHz.

Abstract: A power amplifier includes an inverter amplification section configured to amplify AC components and remove DC components from at least one input signal, an impedance matching section configured to match an impedance of a transmission path of the at least one input signal amplified by the inverter amplification section, and an amplification section configured to amplify an impedance-matched signal from the impedance matching section according to a predetermined gain. The inverter amplification section includes at least one P-channel metal-oxide semiconductor field effect transistor (MOS FET) having a gate configured to receive the at least one input signal and at least one N-channel MOS FET having a gate configured to receive the at least one input signal. The at least one P-channel MOS FET and the at least one N-channel MOS FET are serially connected.

Abstract: According to an embodiment, a method is provided that includes: adapting the impedance of the load dependent on working conditions of the active device using a controllable output-side adaptation network coupled between an output-side terminal of a transformer and an output-side node, to generate an adapted impedance of the load, adjusting the adapted impedance independent of the working conditions of the active device, using the transformer including a first inductor having a first terminal to receive the output of the active device via the input-side node, a second inductor having an output-side terminal, where the second inductor is magnetically coupled to the first inductor.

Abstract: A power amplifier system can include a plurality of driver amplifiers and a plurality of power amplifiers, where each driver amplifier and power amplifier includes at least one respective input port and at least one respective output port. The power amplifier system also includes a shared inductive device that provides common interstage matching between the respective output ports of the plurality of driver amplifiers and the respective input ports of the plurality of power amplifiers. The shared inductive device can be a shared inductor or a shared transformer.

Abstract: The present disclosure relates to coupled circuits and methods of coupling circuits having a power supply wherein a plurality of transistors are inductively coupled directly to the power supply for providing a single DC supply voltage directly to each of the plurality of transistors, and wherein a plurality of transformers have primary and secondary windings, the primary and secondary windings providing, at least in part, inductive loads for inductively coupling the plurality of transistors to the power supply, the plurality of transformers also providing an AC signal path for coupling neighboring ones of the plurality of transistors together.

Abstract: There is provided a multi-stage CMOS power amplifier including: a driver amplifier having differential output terminals, inverting differential signals input through first and second input terminals and outputting the respective inverted signals through the differential output terminals; a transformer for power matching having a primary coil connected between the differential output terminals of the driver amplifier and a secondary coil coupled with the primary coil using electromagnetic induction, having a predetermined turns ratio to the primary coil, and connected to a direct current (DC) tuning voltage terminal; and a power amplifier power-amplifying differential signals passing through one end and the other end of the secondary coil of the transformer and outputting the respective power-amplified differential signals through first and second output terminals.

Abstract: A power amplifier system can include a plurality of driver amplifiers and a plurality of power amplifiers, where each driver amplifier and power amplifier includes at least one respective input port and at least one respective output port. The power amplifier system also includes a shared inductive device that provides common interstage matching between the respective output ports of the plurality of driver amplifiers and the respective input ports of the plurality of power amplifiers. The shared inductive device can be a shared inductor or a shared transformer.

Abstract: Embodiments of the invention may provide for power amplifier systems and methods. The systems and methods may include a power amplifier that generates a first differential output signal and a second differential output signal, a primary winding comprised of a plurality of primary segments, where a first end of each primary segment is connected to a first common input port and a second end of each primary segment is connected to a second common input port, where the first common input port is operative to receive the first differential output signal, and where the second common input port is operative to receive the second differential output signal, and a single secondary winding inductively coupled to the plurality of primary segments.

Abstract: In one implementation, the present invention includes a diode device to receive an incoming radio frequency (RF) signal to be amplified in a gain device of an amplifier and to provide a pre-distorted signal. Based on this pre-distorted signal, the gain device can output an amplified RF signal having substantial linearity to the incoming RF signal.

Abstract: Techniques for improving the quality factor (“Q”) of a balun in the presence of loading stages are disclosed. In an exemplary embodiment, the ground node of a balun secondary (single-ended) element is connected to a source node of an amplifier stage via a common ground node. The connection may be made physically short to minimize any parasitic elements. In another exemplary embodiment, the common ground node may be coupled to an off-chip ground voltage via a peaking inductor. The peaking inductor may be implemented on-chip, e.g., as a spiral inductor, or off-chip e.g., using bondwires.

Abstract: A transformer power combiner having a plurality of input ports and an output port is provided. The transformer power combiner includes a plurality of primary winding conductors and a plurality of secondary winding conductors. The primary winding conductors are electrically connected to the input ports, respectively; in addition, each of the primary winding conductors is electrically connected between a positive terminal and a negative terminal of a corresponding input port. The secondary winding conductors are magnetically coupled to the primary winding conductors, respectively. The secondary winding conductors are configured in a topology including series connection and parallel connection between a positive terminal and a negative terminal of the output port.

Abstract: A low frequency amplifier uses a switched bridge circuit, providing a first frequency output. A transformer circuit receiving the first frequency output from the switched bridge circuit. Power from the transformer is output from a plurality of secondaries and the power from the secondaries is supplied to the corresponding output switching circuits and provided as switched outputs from the transformer circuit. The switched outputs from the transformer circuit are responsive to a transformer output from the transformer at the first frequency, and switch the transformer outputs in a timed sequence to provide a combined second frequency output. The second frequency output has a lower frequency than the transformer outputs.

Abstract: Circuits and methods are provided for building integrated transformer-coupled amplifiers with on-chip transformers that are designed to resonate or otherwise tune parasitic capacitances to achieve frequency tuning of amplifiers at millimeter wave operating frequencies.

Abstract: A differential amplifier is formed from a first single-ended amplifier circuit, a second single-ended amplifier circuit, and a four-port transformer circuit coupled to the first and second single-ended amplifier circuits to form the differential amplifier.

Abstract: Embodiments of the invention may provide for power amplifier systems and methods. The systems and methods may include a power amplifier that generates a first differential output signal and a second differential output signal, a primary winding comprised of a plurality of primary segments, where a first end of each primary segment is connected to a first common input port and a second end of each primary segment is connected to a second common input port, where the first common input port is operative to receive the first differential output signal, and where the second common input port is operative to receive the second differential output signal, and a single secondary winding inductively coupled to the plurality of primary segments.

Abstract: Various methods, apparatuses, and systems are described in which devices having no common electrical ground communicate. In at least certain embodiments, an apparatus includes a transformer block to communicate a plurality of data signals and a synchronous clock signal between a first device with a first ground reference and a second device with a second ground reference over a data communication link. The first device sends the plurality of data signals to a modulator block having one or more Boolean logic gates that receive each data signal in combination with the synchronous clock signal. The modulator block sends a plurality of modulated data signals corresponding to the plurality of data signals to the transformer block. The transformer block sends the plurality of modulated data signals and the synchronous clock signal to the second device to provide the data communication link between devices having different ground references.

Abstract: Circuits and methods are provided for building integrated transformer-coupled amplifiers with on-chip transformers that are designed to resonate or otherwise tune parasitic capacitances to achieve frequency tuning of amplifiers at millimeter wave operating frequencies.

Abstract: Circuits and methods are provided for building integrated transformer-coupled amplifiers with on-chip transformers that are designed to resonate or otherwise tune parasitic capacitances to achieve frequency tuning of amplifiers at millimeter wave operating frequencies.

Abstract: A method and apparatus provides an input structure for a power amplifier. In one example, the input structure has an input network and a predriver circuit to provide an input signal to the power amplifier. The input network includes a transformer for helping to maintain a constant input impedance. The predriver includes a limiting amplifier that provides isolation between the power amplifier and the RF input. A DC feedback circuit is used by the predriver that maintains the DC level of the inverters to a desired level.

Abstract: Embodiments of the present invention include a common-gate amplifier having an input terminal and an output terminal, a transistor having a source, a drain, and a gate, four inductors, and two capacitors, and a negative amplification circuitry. The negative amplification circuitry has an input terminal to receive an RF signal. The negative amplification circuitry applies negative or zero amplification to the RF signal and outputs the negative or zero amplified signal on an output terminal. Alternative embodiments include a Colpitts differential oscillator, which includes two Colpitts single-ended oscillators. Each Colpitts single-ended oscillator includes a transistor. The source of the transistor in one Colpitts single-ended oscillator may be capacitively coupled to the gate of the transistor in the other Colpitts single-ended oscillator.

Abstract: Provided is a frequency converter using an amplification circuit that is improved with linearity by coupling a main transistor and an auxiliary transistor in parallel. An amplification circuit that is improved with linearity comprises an input block amplifying an input signal, an induction block inducing a current proportionate to an output signal of the input block and an amplification block comprising. The amplification block comprises a main transistor amplifying the output signal of the induction block, wherein the main transistor is biased to operate at a saturation region and an auxiliary transistor amplifying the output signal of the induction block, wherein the auxiliary transistor is biased to operate at a subthreshold region and coupled to the main transistor in parallel.

Abstract: A method and apparatus provides an input structure for a power amplifier. In one example, the input structure has an input network and a predriver circuit to provide an input signal to the power amplifier. The input network includes a transformer for helping to maintain a constant input impedance. The predriver includes a limiting amplifier that provides isolation between the power amplifier and the RF input. A DC feedback circuit is used by the predriver that maintains the DC level of the inverters to a desired level.

Abstract: A system and method for employing variable magnetic flux bias in an amplifier. The amplifier system comprises an output transformer and a magnetic sensor configured to sense a first magnetic flux of the output transformer. The magnetic sensor generates a flux signal responsive to the first magnetic flux. Control circuitry is configured to receive the flux signal and to generate a control signal responsive to the flux signal. A winding is configured to receive the control signal and to induce a second magnetic flux within the output transformer responsive to the control signal, the second magnetic flux having opposite polarity to the first magnetic flux. The second magnetic flux may maintain a non-zero quiescent magnetic bias level within the output transformer, or may substantially cancel or null the DC and low-frequency subsonic components of the first magnetic flux.

Abstract: Circuits and methods are provided for building integrated transformer-coupled amplifiers with on-chip transformers that are designed to resonate or otherwise tune parasitic capacitances to achieve frequency tuning of amplifiers at millimeter wave operating frequencies.

Abstract: An amplifier circuit includes a transistor having a control terminal, a first and a second terminal, a signal input terminal coupled to the control terminal of the transistor, as well as a transformer with a primary side and a secondary side, the primary side of which is coupled to the first or second terminal of the transistor. The amplifier circuit further includes a signal output terminal coupled to the secondary side of the transformer. Hereby it is possible to provide an amplifier circuit with a better characteristic as opposed to a conventional amplifier circuit, which is further easy to manufacture.

Abstract: A power supply for a guitar amplifier and the guitar amplifier and method of operating the guitar amplifier. The power supply includes an alternating current power input having a secondary winding and a filament winding, an output and a first vacuum tube rectifier coupled between the secondary winding of the power input and the output for rectifying the alternating current at the power input. At least a second rectifier is provided which is selectively couplable in parallel with the first vacuum tube rectifier. The at least one second rectifier can be a vacuum tube rectifier with each of the first and second rectifiers having a cathode continually energized by the filament winding, a solid state rectifier or both. The output amplifier has an output transformer having a primary winding with a center tap and with a first pair of vacuum tube amplifiers having their cathodes being coupled together and their plates coupled to the primary winding on opposite sides of the center tap.

Abstract: A method and apparatus provides an input structure for a power amplifier. In one example, the input structure has an input network and a predriver circuit to provide an input signal to the power amplifier. The input network includes a transformer for helping to maintain a constant input impedance. The predriver includes a limiting amplifier that provides isolation between the power amplifier and the RF input. A DC feedback circuit is used by the predriver that maintains the DC level of the inverters to a desired level.