Abstract: Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.

Abstract: A transimpedance amplifier includes a T-coil in its feedback loop to expand its bandwidth. The transimpedance amplifier includes an amplifier that converts and amplifies an input current signal to an intermediary voltage signal. One terminal of the T-coil is coupled to a resistor in the feedback loop which is coupled to the input of the amplifier. Another terminal of the T-coil is coupled to the output of an amplifier. The bridge point of the T-coil is coupled to the output terminal of the transimpedance amplifier which outputs an output voltage. The T-coil includes two inductors that are mutually coupled such that a current is induced to compensate for the leakage current caused by the parasitic capacitance of the transimpedance amplifier.

Abstract: Aspects of the disclosure provide a power circuit that includes a first switch module and a second switch module in parallel. The first switch module has a first gate terminal, a first drain terminal and a first source terminal, and the second switch module has a second gate terminal, a second drain terminal and a second source terminal. A drain interconnection module coupled to the first drain terminal and a gate interconnection module coupled to the second gate terminal are inductively coupled to balance current flowing through the first switch module and the second switch module.

Abstract: A highly efficient, high control bandwidth and high-speed power supply with a linear driver and a switching regulator for regulating an output based on a control signal. The linear driver has a first input for receiving the control signal and a second input connected to the output for receiving negative feedback. The driver's output is controlled by its two inputs and has a capacitor connected in series with it to generate a capacitor voltage VC responsive to the DC and low frequency components in the driver's output. The switching regulator has a control input and a regulator output connected in a regulator feedback loop. The control input receives capacitor voltage VC and the regulator feedback loop minimizes capacitor voltage VC. Thus, switching regulator takes over the generation of DC and low frequency components, while the linear driver provides high frequency output current components.

Abstract: An integrated circuit includes a radio frequency (RF) amplifier having a trifilar transformer coupled to a gain device in two negative feedback paths. The trifilar transformer includes a first winding, a second winding and a third winding, a first dielectric core is disposed between the first winding and the second winding, and a second dielectric core is disposed between the second winding and the third winding. A first winding ratio between the first winding and the second winding combined with a second winding ratio between the second winding and the third winding affects a total gain of the RF amplifier. In a specific embodiment, the gain device is a transistor, the first winding is coupled to a base of the transistor, the second winding is coupled to a collector of the transistor, and the third winding is coupled to an emitter of the transistor.

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: An RF amplifier system having closed cavity containing an amplifying device that includes at least a cathode, an anode and a grid and wherein the amplifying device exhibits an internal grid-to-anode capacitance. Apparatus is presented for use in neutralizing the internal capacitance. This includes a feedback circuit including an external capacitor of fixed value and a phase inverting transformer having a transformer primary winding connected in series with the capacitor to the cathode. The transformer has a secondary winding connected between the cathode and the grid for supplying a phase inverted negative feedback voltage to the grid for neutralizing the cavity by the feedback voltage. The transformer coupling is adjustable to vary the magnitude of the feedback voltage.

Abstract: A low noise amplifier having a wide operating frequency band and a high dynamic range is provided. A transformer having a secondary winding connected between an input terminal to which an input signal is applied and a positive differential output terminal, and a primary winding connected between a negative differential output terminal and an input node is provided as a feedback circuit between a cascode amplifier circuit, which includes transistors and a resistor, and an output circuit, which includes a transistor and a constant current source. Selective use of a transformer whose leakage inductance has an adequate value as the feedback transformer can realize a low noise amplifier which has a wide operating frequency band and a high dynamic range.

Abstract: A low-noise amplifier, that utilizes multiple monolithic transformer magnetic feedback to simultaneously neutralize the gate-drain overlap capacitance of the amplifying transistor and achieve high gain at high frequencies when driving an on-chip capacitance, is shown. The multiple transformer topology permits negative and positive feedback to be applied constructively, allowing for a stable design with adequate gain and large reverse isolation without Noise Figure degradation.

Abstract: The push-pull amplifier with transformational negative feedback is provided for amplification of variable electrical signals. It includes a signal input and a signal output, a transformational negative feedback connected with the signal input and the signal output and an amplifier circuit. The amplifier circuit includes an input and an output as well as a first transistor and a second transistor. The input of the amplifier circuit is thereby connected with the signal input and the output of the amplifier circuit is thereby connected with the signal output via the transformational negative feedback.

Abstract: A low-noise preamplifier with an electronic amplifying element having an input (2) and an output (4), and with a first transformer (6) having a primary winding (5) and a secondary winding (8) is characterized in that the input (2) of the electronic amplifying element is the base of a transistor, the gate (G) of a field effect transistor (FET) or the grid of a vacuum tube, and the output (4) of the electronic amplifying element is the collector, the drain (D) or the anode, the output current (Ip) being passed from the electronic amplifying element through the primary winding (5) of the first transformer (6) to the output (7) of the preamplifier, wherein the secondary winding (8) of the first transformer (6) is connected to the input (2) of the electronic amplifying element. This preamplifier can be operated with extremely low noise and at any input impedance, in particular, at 50 ohms or 75 ohms.

Abstract: Continuous alternating current is derived from a differential operational amplifier supplied by direct current. The differential operational amplifier produces alternating current located on the positive input of the differential operational amplifier. Output of the differential operational amplifier is received by a transformer to produce alternating current. Voltage from the transformer is fed back to the negative input of the differential operational amplifier to provide feedback for the differential operational amplifier. Whereby direct current provided to a differential operational amplifier is transformed to continuous alternating current.

Abstract: A line driver combining active impedance and filter in one stage for connection to a transmission line having a characteristic impedance. The line driver comprises an amplifier, a transformer with a primary to secondary winding ratio of 1:n, a reference impedance, an input impedance and two feedback impedances. The primary winding of the transformer has a first end connected to the output of the amplifier and the secondary winding is connectable to the transmission line. The reference resistor has an end connected to the second end of the first winding at a junction node and the feedback circuit is connected to the input and output of the amplifier and also to the junction node. The reference impedance has a value equal to n 2 K times the characteristic impedance of the transmission line.

Abstract: A wideband amplifier comprises a dual-emitter bipolar transistor arrangement with coaxial transformers, each having a high turns ratio and tight coupling between a first toroidal winding on an annular ferrite core and a second, single-turn, winding constituted by a metal container of the transformer. The second windings are coupled between respective emitters and signal ground, and the first windings are connected between the transistor base and collector, respectively, and signal ground. An input signal is supplied to the base, and an output signal is derived from the collector. The dual-emitter bipolar transistor, which has four terminals, is thereby transformed into a two-port (input port and output port) device which facilitates impedance matching, provides a linear and constant gain over a large bandwidth, provides high isolation of the input from the output, and provides low noise at the input and a high level at the output.

Abstract: A meter circuit for measuring the effective series resistance (ESR) and Q-Factor of a capacitive device has an operational amplifier with an input to which a source of AC input voltage is applied. A feedback circuit is connected between output and input of the amplifier. A series network is connected between the feedback circuit and ground. This network has an inductor of known Q-Factor in series with a capacitive device whose Q-factor is to be determined. Voltmeters measure the applied input voltage and output voltage of the amplifier. Where the series resistances of the inductor and capacitive device at resonance frequency have a low total magnitude, the meter circuit can be modified by inserting a wideband transformer, having very low output impedance, in the feedback circuit in series with an adjustable gain operational amplifier.

Abstract: A driver circuit for applying a first signal having a desired wave form, frequency and peak to peak voltage to a coaxial transmission line which also has applied to it a second signal having a substantially higher frequency. An operational amplifier has the first signal applied to its noninverting input terminal. The output of the operational amplifier is applied across the primary winding of a driver coupling transformer through an inductor which provides high impedance to the second signal. The voltages induced in the secondary winding of the driver transformer are applied to the transmission line. The primary winding of a feedback transformer is connected in parallel with the secondary winding of the driver transformer. The voltage induced in the secondary winding in the feedback transformer are applied by a feedback circuit including an R.C. filter to the inverting input terminal of the operational amplifier. The signal applied to the inverting input terminal includes both an A.C. component and a D.C.

Abstract: An amplifier uses non-dissipative elements to provide current and voltage feedback. The base amplifier has two input terminals, and the current and voltage feedback signals are applied to respective input terminals. The non-dissipative elements may be either transformers or coupled-line pairs. These elements allow broad band operation with low noise. The feedback configuration results in higher input impedence.

Abstract: In amplifier circuit arrangements for low-distortion transmission of audio signals a transformer is provided in order to isolate a source circuit from an amplifier of the amplifier circuit arrangement. Good transmission characteristics, however, can only be obtained in such circuit arrangements by using transformers of comparatively great dimensions. In order to achieve improved transmission characteristics and yet design the transformer in such a manner as to have small size, to be of low weight and inexpensive, the amplifier of the amplifier circuit arrangement is provided with a negative feedback circuit. This negative feedback circuit is connected to the source circuit by using a transformer connected in series with the current-voltage source of such source circuit.

Abstract: An arrangement to provide feedback to amplifier systems incorporating an electrical load. A current transformer in conjunction with a resistor is incorporated to provide a feedback correction signal to an amplifier which corrects for distortion caused by both the amplifier and the inductive load. A first embodiment provides a single-ended amplifier driving a load and incorporates the current transformer between the output of the amplifier and the load. The secondary winding of the transformer is in series with the input to the amplifier, and a resistor is connected across the secondary winding. The transformer determines the frequency bandwidth of the entire amplifier system, and the resistor value determines the gain of the amplifier. Such a configuration provides negative feedback to the amplifier which is directly proportional to changes in current in the load due to distortions caused by the amplifier or load.