Abstract: The present subject matter relates to the control of electromagnetic fields and has particular relevance to wireless power transfer system devices and systems. In particular there is provided a magnetic flux coupling apparatus comprising a coil for generating or receiving magnetic coupling flux; and a leakage flux element separated from the coil by a region of relatively low magnetic permeability and positioned to provide a controlled path for leakage flux independent of coupling flux; wherein the leakage flux element comprises a lossy magnetic material of relatively high magnetic permeability which absorbs energy from a time varying magnetic field to thereby alternate attenuate leakage flux. The apparatus as disclosed herein aids in the suppression of the magnetic flux that leaks out of the air gap in such systems, or which leaks out of a region where magnetic flux is required for inductive power transfer.

Abstract: A coaxial transmission line structure having a center conductor section having an input contact and an output contact the output contact being larger than the input contact, the center conductor having a plurality of different geometrically shaped, electrically conductive layers having sizes progressively increasing from the input contact to the larger output contact to conductor transition from the input contact to the larger output contact, the electrically conductive layers being electrically interconnected by staggered microvias passing through dielectric layers to the center, and (B) an outer conductor section disposed about, coaxial with, and electrically isolated from, the center conductor by the dielectric layers.

Abstract: A linearizer for reducing intermodulation distortion in a non-linear device. The novel linearizer includes an input port for receiving a signal from the device and a circuit for effecting gain expansion on the signal that counteracts a gain compression of the device. In an illustrative embodiment, the circuit includes a starved limiter in shunt with the device, implemented using a pair of biased diodes D1 and D2. The first diode D1 is connected to ground and the second diode D2 is coupled to the signal. In an alternate embodiment, the linearizer also includes a second pair of biased diodes D3 and D4, D3 connected to ground and D4 coupled to the signal, and a plurality of reactive elements for increasing the operational bandwidth of the linearizer.

Abstract: First and second parallel conducting plates include arrayed conducting segments, preferably with specific spacing relative to each other and to the separation of the plates. Currents through the conducting segments are pulsed and phased to produce constructive but unequal interference on the two plates. Among other things, the net result of the interference can produce a net force on the device, and in that manner can be used for propulsion. Preferred devices have up 100 segments or more.

Abstract: In the present invention, in parallel with a resistor which determines an amplification rate being fed back from an output to an input of an output stage OP amp in an audio amplifier circuit, providing a first diodes connected bi-directionally together with a first switch circuit, the output voltage of the output stage OP amp is limited to a voltage, when the first diodes are turned ON. The limit voltage of the first diodes corresponds to a speaker having a low withstand voltage. Accordingly, through ON/OFF of the first switch circuit, a power output from the output stage OP amp can be selected depending on the withstand voltage of a speaker to be connected.

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: The voltage generator comprises a negative feedback loop including a programmable voltage divider having a feedback node. The voltage divider comprises a programmable resistor disposed between the output of the voltage generator and the feedback node and having variable resistance. The programmable resistor includes a fixed resistor and a plurality of additional resistors arranged in series with each other and defining a plurality of intermediate nodes. The additional resistors may be selectively connected by means of switches disposed between the output of the voltage generator and a respective intermediate node so as to define an output voltage V0 programmable on the basis of command signals supplied to the switches.

Abstract: A radio repeater wherein a reflective negative resistance amplifier, using the negative resistance of a Gunn diode, is applied at one side of a dielectric waveguide, enabling signals to be inputted through the input terminal dielectric waveguide, circulated in the circulator and enter the Gunn diode. Reflected waves amplified in the Gu diode exit the output terminal dielectric waveguide. A radio repeater is provided on the non-radiative dielectric waveguides using the multi-space non-radiative dielectric waveguides, which receives a frequency, amplifies it, and retransmits the amplified signals to any direction. With a dielectric band inserted in the radio repeater, directions for reception and transmission can be freely changed. Using the radio repeater, a small size radio repeater of low power consumption may be made.

Abstract: A high frequency amplifier with the multi-space structure, amplifying various frequencies by a Gunn diode in the multi-space structure, composed of non-radiative dielectric waveguides of various different sizes. An amplifier circuit includes a Gunn diode inserted in a space between two metal plates of a certain distance from each other, a circulator which revolves input waves and determines transmission direction, a first non-radiative dielectric waveguide, which is connected to the circulator, sending the input waves from the input terminal to the circulator, a second non-radiative dielectric waveguide, which is connected to the circulator, sending the input signals from the circulator to the Gunn diode and sends the amplified signals from the Gunn diode back to the circulator; and a third non-radiative dielectric waveguide, which is connected to the circulator, sending the amplified signals, which come into the circulator through the second non-radiative dielectric waveguide, to the output terminal.

Abstract: A microwave power combiner is formed in a cylindrical hollow metallic housing utilizing a number of pie shaped chambers formed with metallic vanes attached to and extending radially inward from the interior sidewalls of the cylindrical hollow metallic housing. Individual microwave power sources exterior to the cylindrical hollow metallic housing transmit energy into the pie shaped chambers. Two ring shaped metallic vane straps are used to control impedance mismatches and the resonant frequency of the microwave power combiner. The microwave power from the individual microwave power sources combine in the cylindrical hollow metallic housing and is extracted through the circular top of the cylindrical hollow metallic housing by means of a waveguide or a transmission line. The individual microwave power sources can be replaced as needed without affecting impedance matching or the efficiency of power transfer. There is flexibility in the number of individual microwave power sources used.

Abstract: A microwave power combiner includes a first plate having disposed in a first surface thereof a first plurality of grooves and a second plate having disposed in a first surface of said second plate a second plurality of grooves, with said second plate being mated to said first plate and with said first plurality of grooves in the first plate disposed in alignment with the second plurality of grooves in the second plate to provide a plurality of waveguide regions. The waveguide regions are further disposed to provide a plurality of hybrid Ts preferably matched hybrid Ts or magic Ts which are selectively interconnected to form an integrated combiner structure. A first surface of the plate is used to mount a plurality of IMPATT diode modules whereas the second opposite surface of the composite plate is used to mount a heat sink thereby providing a thermal path between the diode modules through the composite plates to the heat sink.

Abstract: A microwave power combiner includes a first plate having disposed in a first surface thereof a first plurality of grooves and a second plate having disposed in a first surface of said second plate a second plurality of grooves, with said second plate being mated to said first plate and with said first plurality of grooves in the first plate disposed in alignment with the second plurality of grooves in the second plate to provide a plurality of waveguide regions. The waveguide regions are further disposed to provide a plurality of hybrid Ts preferably matched hybrid Ts or magic Ts which are selectively interconnected to form an integrated combiner structure. A first surface of the plate is used to mount a plurality of IMPATT diode modules whereas the second opposite surface of the composite plate is used to mount a heat sink thereby providing a thermal path between the diode modules through the composite plates to the heat sink.

Abstract: An electromagnetic signal processor is disclosed comprising an input waveguide, an intermediate waveguide, and an output waveguide. The intermediate waveguide comprises two portions having substantially equal electromagnetic impedances. The two portions of the intermediate waveguide are coupled to each other at a first and a second junction. The input and output waveguides are electromagnetically coupled to the intermediate waveguide at the first and the second junctions, respectively. Electrically coupled to the intermediate waveguide is a semiconductor device responsible for processing input electromagnetic signals. The input waveguide functions to receive and direct an input electromagnetic signal to the first junction of the intermediate waveguide. At the first junction, the intermediate waveguide separates the input signal into two signals having substantially equal amplitudes.

Abstract: A four diode reflection amplifier having a relatively wide bandwidth of at least 5 percent over the frequency range of 43.5 to 45.5 GHz includes three magic Ts arranged to provide a 4-way passive power combiner. The 4-way passive power combiner symmetrically couples each of the four diode amplifiers to an input/output port of the reflection amplifier. To provide the improved bandwidth performance, a perturbation impedance in the form of a single shunt capacitance is inserted at the input/output port of the reflection amplifier to provide a selected perturbation in the load impedance and hence the reflection characteristic seen by the reflection amplifier over a selected band of operation of the amplifier.

Abstract: A microwave power combiner having a spherical region from which six rectangular waveguides extend oppositely along mutually orthogonal diameters. The long dimension of each waveguide cross section extends along a diagonal of a cube circumscribing the region and extends orthognally to this long dimension of the opposite waveguide. One waveguide is an input for an injection locking signal, and four waveguides are inputs for power to be combined in the region from oscillators controlled by the signal. No circulator is required, and the combined power may be output through the remaining waveguide or through the injection locking input waveguide. A number of the combiners may be connected with the output of one combiner serving as an injection locking input or as one power input to another of the combiners.

Abstract: Disclosed is a power divider/combiner using two parallel plate radial transmission lines having parallel plate spacing of less than .lambda./2 and which operates in a higher order mode, preferably the first higher order circumferential mode TE.sub.11. High isolation between amplifiers coupled to the radial transmission lines at their circumferences is achieved by coupling an arrangement of circulators between the amplifiers and the radial transmission lines. This isolation arrangement reduces the effects of any spurious signals that are generated by means such as imperfections and imbalances in any active devices coupled to the radial line and permits de-energizing amplifiers as desired for lowering power output without degrading performance.

Abstract: A microstrip IMPATT circuit tuning mechanism for use with RF producing IMPATT diode combinations including a microstrip circuit board and a external load line connected by a coupling spring attached to the load line and separated from the microstrip circuit by a dielectric layer, the coupling spring being manipulated by a dielectric screw inserted through the housing containing the microstrip board and further having a metallic frequency controlling screw extending through the housing and terminating before the microstrip board.

Abstract: Disclosed is a parallel plate radial transmission line having parallel plate spacing of less than .lambda./2 and which utilizes a specific higher order mode, preferably the first higher order circumferential mode. Undesired modes are suppressed by mode supression slots formed in one or both of the parallel plates and which are oriented parallel to the current flow lines of the particular mode that is used. These slots have a negligible effect on the mode being used but they couple out other modes that are generated by means such as by imperfections and imbalances in any active devices coupled to the radial line. A centrally located feed is used to launch circularly polarized energy of the TE.sub.11 mode in the particular circumferential mode in the radial line. The feed may also receive circularly polarized energy of the particular circumferential mode in the radial line, linearly polarize that received energy and conduct it in the TE.sub.11 mode.

Abstract: Structures (30) with IMPATT type diodes (34) located periodically along a transmission line (38-32) to simulate a distributed diode are disclosed. Preferred embodiments include incorporation of the periodic diode structures as the gain element of microwave amplifiers and oscillators. Preferred embodiments also place capacitors between the diodes to fix nodes in the electric field and increase the effective structure size.

Abstract: A method and arrangement for enhancing the level of supplied microwave energy including a resonant ring capacitively coupled to a microwave coupling device effective for connecting to a microwave transmission line, the arrangement being mounted in a shield structure. Amplification is effected by IMPATT diodes capacitively coupled to the resonant ring. The microwave coupling device is variably setable with respect to the transfer structure, thereby promoting the establishment of impedance matching therebetween.

Abstract: An IMPATT diode mounted in a double-tuned resonant cavity to exhibit stability by suppressing subharmonic frequencies is disclosed. A foreshortened quarter wavelength section is connected to the diode to form an equivalent parallel resonant circuit at one end thereof. At the other end of the quarter wavelength section is an odd-quarter wavelength tuning slug which provides a section which exhibits a second, series equivalent resonant circuit. To provide increased stability at subharmonic frequencies, a half-wavelength tuning slug is disposed adjacent to the odd-quarter wavelength section. The half wave tuning slug is virtually transparent at the operating frequency, but is a quarter-wavelength at the first subharmonic, and thus exhibits a high resistance at the subharmonic frequency.

Abstract: An apparatus and method is disclosed for providing a planar disc resonator oscillator/amplifier which consists of a planar radial disc resonator, a substrate having a hole extending therethrough, a negative impedance device, and a conductor having a predetermined width. The oscillator/amplifier having an external quality factor dependent upon the width of the conductor and upon the distance between the centers of the planar radial disc resonator and the negative impedance device.

Abstract: A plurality of negative resistance devices is spaced below a cylindrical center conductor of a single coaxial cavity. Each negative resistance device has a bias device connected to it by a bias wire. Extending radially through the outer wall of the coaxial cavity is a coax cable with an RF coupling probe. A tuning screw is place axially through the interior of the center conductor for tuning the frequency of the power combiner.

Abstract: A two-port monolithic microwave amplifier, which uses a distributed negative resistance diode with gain (such as an IMPATT diode) as an active element. The diode is tapered (increasing in width but not in thickness) so that, as the RF signal propagates along the diode, it sees a wider and wider active diode region. This diode is operated in the power-saturated region, so that, as the RF signal propagates along the diode, terminal voltage remains essentially constant, but the RF current increases. This configuration is inherently undirectional.

Abstract: An improved microwave amplifier is shown to comprise an IMPATT diode in a coaxial circuit coupled to a section of double-ridged waveguide forming a resonant cavity with a low Q, such cavity in turn being coupled to outside circuitry through a compound iris.

Abstract: In a distributed IMPATT structure, power is coupled out through a side contact. That is, in previously proposed distributed IMPATT structures the gain medium (the active region of the IMPATT) operates as a transmission line. The prior art has attempted to couple output power from the gain medium through an end contact, i.e. through a contact which intercepts the primary direction of energy propagation of the active medium. In the present invention, a side contact extends along the whole active region in a direction which is parallel to the principal direction of propagation of the energy in the active medium. Thus, the side contact plus the active region together can be considered as a single transmission line.The present invention can be configured as an oscillator, amplifier, phase shifter, or attenuator. When configured as an oscillator, multiple short active regions can be sequentially coupled to a single long microstrip, which serves as the side contact for each of the active regions.

Abstract: A waveguide amplifier circuit has two semiconductor amplifier elements in a first waveguide circuit, a second waveguide circuit which is perpendicular to the first waveguide circuit and a termination circuit arranged at an end, remote from the semiconductor amplifier elements, of the second waveguide circuit. An abnormal oscillation component between the two semiconductor amplifier elements is attenuated by the second waveguide circuit and the termination circuit, thereby obtaining a high power output.

Abstract: A primed oscillator for microwave amplification includes a single tank conductor (16) coupled to a coupling conductor (17) by an interdigitated coupler (26). The coupling conductor (17) is connected to the cathode of an IMPATT diode (22) which is triggered by the application of a back-biasing trigger pulse that biases it into its negative-resistance region. When a keying pulse is applied to the IMPATT diode (22), the diode couples power through the interdigitated coupler (26) to the tank circuit (16) to cause oscillations that are initially in phase with any incoming signals, but the frequency of the oscillations is determined by the configuration of the tank circuit (16), not by the frequency of the incoming signal. If the incoming signal is near enough to the resonant frequency, and if the duration of the keying pulses is short enough, the output of the primed oscillator appears to a band-limited receiver to be an amplified version of the input signal.

Abstract: A typical coaxial circuit which couples a negative resistance diode to the cavity of a power combiner consists of a metallic rod which is biased by a spring against the diode supported by a carrier which is effective to vary the position of the diode along the longitudinal axis of the rod. The rod cooperates with bores in a block to comprise, in series, between the diode and the cavity, a transmission line whose length varies in accordance with diode position, a fixed impedance transformer and a fixed length transmission line.

Abstract: An improved microwave circuit is disclosed for enabling impedance tuning for power coupling in IMPATT diode and other similar oscillator and amplifier circuits. An electrically conductive support plate forming a ground plane is machined to form a channel for slidably receiving an air-stripline transmission line and a resonator therein. An IMPATT diode is positioned within the channel through an opening extending through the support plate generally perpendicular to the channel and is positioned in contact with the resonator. An electrically conductive bias filter is coupled to the resonator and to an adjusting mechanism for moving the resonator along the channel and providing a DC bias to the diode for oscillation. An electrically conductive cover member retains a spring biased electrically non-conductive projection for maintaining the resonator in contact with the diode.

Abstract: A microstrip integrated circuit reflection amplifier utilizing packaged diodes and permitting some gain and bandwidth adjustment. A 3 db quadrature coupler has two of its ports connected to substantially identical reflection amplifiers. The reflection diodes are adjustably mounted in brackets perpendicular to the dielectric substrate of the microstrip network and may be moved in and out along the microstrip circuit to provide for some gain correction and bandwidth adjustment.

Abstract: The diode bias input terminals of an IMPATT microwave power combiner are resistively coupled to a common floating node to provide stabilization of the operating points of the individual IMPATT diodes, thus minimizing the tendency of the diodes to contribute unequally to total RF output, particularly in a varying temperature environment. The optional inclusion of RF lossy bypass capacitors to ground several points of the common node suppresses bias circuit oscillations.

Abstract: An impedance transforming hybrid ring has a non-uniform impedance ring structure coupled to four ports. Two of the ports function as input ports, the remaining two as output ports. An arbitrary relationship exists between the impedance of the input ports and the impedance of the output ports. The power division between output ports may be selected as a matter of design choice. A broad band phase reversing network is utilized to provide an impedance transforming hybrid ring which efficiently operates over octave bandwidths. Design equations are provided and method for utilizing same are disclosed.

Abstract: A protection circuit for an Impatt amplifier includes a voltage comparator which is arranged to sense the terminal voltage of the or each Impatt diode. When the comparator senses that a diode terminal voltage has risen above a predetermined value a circuit is actuated which causes power to be disconnected from the amplifier. The present circuit does not require the use of expensive couplers.

Abstract: A microwave combiner assembly is described incorporating a coaxial transmission line having a plurality of diodes exhibiting negative resistance at high frequency mounted between the center conductor and the outer conductor of the transmission line. Each diode is mounted on a segment forming a portion of the center conductor which are separated by slots containing lossy dielectric. A signal is capacitively coupled from each diode by capacitively coupling each segment to a common center conductor. Each diode is biased by coupling a bias voltage to each segment. The microwave combiner overcomes the problem of mechanically assembling a plurality of diodes in an oscillator or amplifier while attenuating anti-phase currents in the diodes indicative of undesired oscillator modes.

Abstract: A multiple channel amplifier providing both gain and/or phase shift to a microwave signal is formed of a set of transmission lines connected in parallel by means of a power splitter at the input end and a power combiner at the output end of the set of transmission lines. The transmission lines are disposed in a cylindrical array of electrically conducting bars which support amplifying and/or phase shifting elements between the bars and withdraw heat from the amplifying and/or phase shifting elements. The transmission lines may be slotted or severed for directing power flow towards an output terminal of the amplifier. The amplifying and/or phase shifting elements are conveniently mounted on a set of heat sinks to form modules, each of which is readily inserted and detached from the cylindrical array.

Abstract: A circuit arrangement for generating and stably amplifying broadband rf signals. The circuit arrangement includes a first rectangular waveguide designed for operation in a frequency range below its cutoff frequency and a second rectangular waveguide for operation at the operating frequency. An active semiconductor element is disposed in the first rectangular waveguide and a direct voltage is supplied to the semiconductor element. At least one waveguide section is provided for connecting the first and second rectangular waveguides and has the same width as the second rectangular waveguide and a height less than the second rectangular waveguide. The waveguide section matches the cross section of the first rectangular waveguide to the cross section of the second rectangular waveguide.

Abstract: A circuit capable of providing the negative resistance heart of oscillators or amplifiers in the 5-20 Gc/s frequency band, comprising a central resonant cavity and one or several peripheral exciting chambers, each containing a push-pull arrangement of two diodes for example three pairs of diodes in chambers arranged at 120.degree. from one another on a circle concentric to the central cavity. The diodes are located at the bottoms of cylindrical exciting chambers communicating with the central chamber through holes situated at the center of each push-pull arrangement. Each pair of diodes is maintained and polarized by a metallic bar which plays, with the walls of the exciting chamber, the role of an impedance transformer between the diodes and the central cavity. The metallic bar is maintained by a polarization rod penetrating the chamber through an insulating passage.

Abstract: An impatt diode in a radio frequency circuit is pulse modulated by a circuit comprising a constant current source providing threshold current and a pulsed current circuit providing drive current. The current applied to the impatt diode by the pulsed current source may be adjusted to increase or decrease as a function of time.

Abstract: A mode filter apparatus for preventing unwanted modes in a multi-moded structure utilizing a radial plurality of resonant slots on the bottom of the filter cavity. The top of the filter cavity includes a variable height center section to provide mode selectivity in cooperation with the resonant slots.

Abstract: An amplifier using a plurality of solid state diodes as the active elements is shown to comprise a plurality of amplifier channels fed, through a first radial line, by signals to be amplified and connected, through a second radial line, to a load.

Abstract: A modular microwave power combiner having a plurality of identical microwave diode amplifier circuits grouped in sets within the body of a modular unit which are electrically coupled in parallel to a central cavity sized to be resonant at a single frequency to minimize mismoding thereby enhancing combiner efficiency. A number of waveguides are provided for coupling of the microwave diode in each amplifier circuit to the resonant cavity, and the waveguides are situated on one side of a PC board at the top of each modular unit. Since each of the modular units is essentially identical in physical size and shape, the overall power output of the power combiner can be increased by merely adding additional modular units. The individual modular units are sized to fit top-to-bottom such that the respective resonant cavities are spaced apart by one-half wavelength (.lambda./2) for the parallel electrical coupling of all of the resonating cavities.

Abstract: A power combining device for combining the microwave power from a plurality of solid state devices comprises a housing defining a resonator cavity with a plurality of co-axial microwave circuits, including a microwave diode at one end of each circuit and a tapered adjustable attenuator at the other end thereof, which are positioned annularly about the resonator cavity so that the energy generated therein is combined within the cavity and transmitted by way of a common outlet. The power combiner is provided with a broad range of bandwidth adjustment by providing for the adjustment of many of the parameters of the system including the length of the circuits, the damping of the circuits, and length of the resonator cavity, and the degree of coupling to adjacent circuits.

Abstract: A hollow cylinder that has a permittivity greater than the permittivity of air is coaxially disposed within a waveguide with the proximal end of the cylinder coplanar with one end of the waveguide. The cylinder has a metal clad surface wherein a plurality of tapered slots that are narrowest at the proximal end of the cylinder and widest at the distal end thereof. The slots are coupled to respective amplification devices, thereby causing the waveguide to be terminated in an impedance substantially equal to impedances of the devices connected in series. Microwave power is transmitted through the waveguide via propagation of a wave in the TE.sub.01 mode. When the wave propagates to the cylinder, the power is transmitted to the devices via the electric fields within the slots at the proximal end of the cylinder. The wave propagates from the cylinder in response to the power being provided by the devices.

Abstract: The basic module of a microwave Travelling-Wave Hybrid Junction amplifier (TWHJ) consists of a hybrid junction (0.degree., 180.degree. or 90.degree. hybrid) combined with an appropriate phase-shifting element (.pi./2 element is needed for 0.degree. and 180.degree. hybrids and no element is needed for a 90.degree. hybrid) and three negative conductance circuits terminating three ports of the modified hybrid while the fourth port serves as an input-output port. Because of proper stabilization and matching, the negative conductance circuits are not oscillating but are acting as reflection type amplifiers. Any RF energy applied to the input port of the hybrid is multiply reflected while travelling through the hybrid giving rise to amplified RF energy emerging from the input port of the hybrid junction.

Abstract: A millimeter wave amplifier having broadband characteristics in which a G diode or other two terminal negative resistance device having an integral heat sink is center mounted in a reduced height waveguide. The heat sink is attached to a mechanism for selectively adjusting its penetration into the waveguide cavity. The introduction of the heat sink into the waveguide cavity creates a discontinuity to the propagation of energy which causes localized waveguide modes other than the dominant mode to exist. The adjustable position of the heat sink allows the reactance due to the introduction of these modes to be variable, proper adjustment resulting in the cancellation of the parasitic reactances inherent in the packaged negative resistance device.

Abstract: A balanced circuit for IMPATT amplifiers and oscillators, which includes at least one pair of anti-series connected matched avalanche diodes electrically connected to the junction of a balanced and an unbalanced transmission line is disclosed. The diodes which are pumped by a large-signal input, are d-c biased to operate in the avalanche condition. A parametrically generated pair of unwanted idler frequencies are separated so that one component of the parametric-pair flows in the balanced line, and the other component flows in the unbalanced line. A central branch of the unbalanced line portion is resistively loaded to overcome the parametrically induced negative resistance of the diodes operating in the avalanche condition, and to suppress all incipient unwanted parametrically generated frequencies. The resistance loading, which is frequency independent, has little effect on the impedance presented to the diodes at the large-signal frequency.

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.