Abstract: Disclosed is a wireless communication system, more particularly, a receiver and a chipset for DSRC.

Abstract: A radio LAN (Local Area Network) system includes an access point and a mobile or a fixed station each having a physical layer implemented by a direct spread spectrum system. The LAN system uses different spread codes, maintains transmission power semi-fixed, and selects a frequency and a frequency band in accordance with the kind and amount of information. A data link layer above each physical layer includes an LLC (Logical Link Control) sublayer and an MAC (Media Access Control) sublayer. The MAC sublayer uses a CDMA (Code Division Multiple Access) system as an access system for thereby implementing a data structure in accordance with the kind and amount of information.

Abstract: Configurable circuits using phase change switches are described. The switches use phase change or phase transition material to create configurable connections between devices and/or interconnecting layers of an integrated circuit in order to change the behavior of the circuit after manufacturing. In at least some embodiments, the phase of the material can be a crystalline phase or an amorphous phase. A phase change can be caused by heating the material, such as with an ohmic heater fabricated on the IC. As one example, germanium-antimony-tellurium (GeSbTe) can be used for the phase change material. The switches can be used to create configurable circuits such as low noise amplifiers and mixers, which can in turn be used to create configurable receivers or other analog circuits.

Abstract: According to one or more aspects of the present invention, a receiver arrangement is disclosed that is configured to receive digital television signals. The receiver arrangement has at least one first frequency conversion device with the signal input, a local oscillator input and an output. The at least one first frequency conversion device is designed to convert a signal which is applied to the input side to an intermediate frequency. A first amplifier is also provided and is designed with amplification in order to compensate for the signal level loss in a filter which is connected downstream from the first amplifier. The first amplifier is coupled to the output of the frequency conversion device. An intermediate-frequency amplifier with a variable gain factor is also provided, and is coupled to the first amplifier. At least the at least one first frequency conversion device the first amplifier are formed in a common semiconductor body.

Abstract: A time division duplex (TDD) wireless apparatus includes a low noise amplifier (LNA) system, at least one antenna and a transceiver system. The apparatus supports N time division duplexed channels which each have a transmit direction of transmission flow and a receive direction of transmission flow. The LNA system comprises N sub-units. Each sub-unit comprises a first circulator for connecting to a respective TX/RX feed to the transceiver system and a second circulator for connecting to the at least one antenna. The first circulator and second circulator within each sub-unit are interconnected to provide a path in one of the directions of transmission flow. The first circulator of each sub-unit is connected to the second circulator of another sub-unit to provide a path in the other direction of transmission flow. A single channel variant is also provided.

Abstract: Aspects of a system for improving efficiency over power control for linear and class AB power amplifiers may include a current source circuit that enables determination of a bias current level for a PA circuit within an IC die based on an amplitude of an input modulation signal. The PA circuit may enable generation of an output signal based on a differential input signal and the input modulation signal to the current source circuit. A generated bias voltage may be applied to a transformer external to the IC die, but internal to an IC package containing the IC die and/or a circuit board containing the IC package. One or more amplifier bias voltage levels may be applied to the PA circuit wherein the amplifier bias voltage levels may be derived from the generated bias voltage level and/or the determined bias current level.

Abstract: Systems and methods are disclosed that use multiple DC-DC (direct-current-to-direct-current) regulators and configurable DC-DC regulators with respect to multi-band audio receivers in order to allow for the use of different DC-DC regulator switching clock signals for different audio broadcast bands. The systems and methods disclosed thereby help to alleviate interference problems typically caused by switching devices used in the DC-DC conversion process. The embodiments described are also applicable to switching power supplies run from alternating current (AC) power sources and to Class D amplifiers working with broadcast radios.

Abstract: DC power savings in a mobile communication device can be achieved by dynamically adjusting the biasing for a receiver based on the communication link quality. The output signal levels of at least one low noise amplifier (LNA) are monitored to identify the DC operating conditions for the LNA. Closed loop control of the DC biasing is adjusted based on a comparison between the monitored DC operating conditions and a reference signal. The output of the LNA is also coupled to a radio receiver section that is configured (e.g., SW or HW) to evaluate the link quality based on various criteria such as inter-modulation distortion, noise, interference, fading, etc. The reference signal that is used to control the DC biasing of the LNA is adjusted (periodically, continuously, or on demand) in response to the evaluated link quality. The dynamic biasing yields acceptable signal reception with low DC power consumption.

Abstract: A low noise amplification circuit comprises a low noise amplifier and a filter coupled to the input terminal of the low noise amplifier. The low noise amplifier comprises an amplifying element and a matching input circuit coupled to the input terminal of the amplifying element. When gamma.sub.s shows a reflection factor in the case that signals flow from the input terminal of the amplifying element to the output terminal of the matching input circuit, impedance conversion for setting the gamma.sub.s at a desired value is made entirely or in part by means of setting the output impedance of the filter at the value different from that of characteristic impedance.

Abstract: An RF amplifier can include a differential inductor for single-ended-to-differential signal conversion. With a center tap of the differential inductor coupled to signal ground and the RF input signal coupled to one of the end taps of the inductor, the negative of the RF input signal is obtained at the other end tap of the inductor. The differential RF signal produced can be coupled to a differential transistor amplifier that has cross-coupling capacitances, improving the signal balance of the differential output signal.

Abstract: A method and circuit for amplifying and demodulating amplitude-modulated signals is disclosed that amplifies a primary signal into an amplified signal, bandpass filters the amplified signal into a filtered signal, compares the filtered signal with a regulation threshold and regulates the gain of the primary signal such that peak values of the filtered signal approach the regulation threshold, compares the filtered signal with a signal threshold, and demodulates the result of the comparison. Whereby a value of the signal threshold is smaller than a value of the regulation threshold.

Abstract: A transmitter and receiver for combining RFID amplitude-modulated data with wireless phase-modulated data is realized by a processing module coupled to generate outbound non-amplitude modulated symbols from first outbound data, to generate outbound amplitude modulated symbols from second outbound data, to generate first inbound data from inbound non-amplitude modulated symbols, and to generate second inbound data from inbound amplitude modulated symbols, a combiner coupled to modulate the amplitude modulated symbols onto a signal carrying the non-amplitude modulated symbols to produce a combined outbound RF signal and a splitter coupled to convert a combined inbound RF signal into inbound non-amplitude modulated symbols and into inbound amplitude modulated symbols.

Abstract: A receiver includes a first receiving section, a second receiving section, and a controller. A controller is operable to switch between a diversity receiving mode in which both of the first receiving section and the second receiving section are activated and a single receiving mode in which the first receiving section is activated while the second receiving section is deactivated. The controller allows the first mixer to heterodyne the signal output from the first RF amplifier with using the second oscillation signal and output the heterodyned signal in the first single receiving mode.

Abstract: An automatic gain control circuit is disclosed. The automatic gain control circuit receives a radio frequency signal at an input. The input passes the radio frequency signal to a first gain loop having a changeable gain. A low pass filter filters the radio frequency signal. In a second gain loop, the gain of the filtered signal is adjusted. The automatic gain control circuit includes at least one signal detector for detecting a signal level in the first gain loop and a signal level in the second gain loop. The automatic gain control circuit also includes an adjustment module for adjusting the gain of the first and second gain loops based upon the detected signal levels wherein overall gain of the first and the second gain loops is increased no greater than a predetermined value.

Abstract: A mode-switching LNA generally includes an input unit, an output unit and a bias voltage generator. The input unit amplifies an input signal to generate an amplified signal. The output unit receives the amplified signal from the input unit and operates either in an oscillation mode or in an amplification mode in response to a control signal to generate an output signal having a center frequency equal to a target frequency. The control signal indicates whether the center frequency of the output signal is the same as the target frequency. The bias voltage generator provides an input bias voltage to the input unit in response to the control signal, where the input bias voltage includes a first bias voltage in the amplification mode and a second bias voltage in the oscillation mode.

Abstract: A first-stage amplifier of an AM receiving circuit is built into an IC 2 as a differential amplifying circuit 3. The differential amplifying circuit 3 is connected to one pad P1 of the IC 2. Then, a high pass filter is configured by connecting a resistor Ra between two input terminals of the differential amplifying circuit 3 and connecting a capacitor Ca between the resistor Ra and ground and in series with the resistor Ra and ground. Thus, the resistor Ra and capacitor Ca integrated into the IC 2 allows hum noise to be removed.

Abstract: A signal processing circuit is proposed, which is intended to receive a pair of input signals Sp and Sn in phase opposition on two input terminals and to provide two pairs of output currents SIp and SIn in phase opposition on four output terminals. Each input signal Sp and Sn is amplified in an amplification unit LNAUp and LNAUn and subsequently split in a splitting unit SPLUp and SPLUn. The invention is such that each of the two splitting units SPLUp and SPLUn includes at least two branches, respectively BIp, BQp and BIn, BQn connected between said amplification unit, respectively LNAUp and LNAUn, and one of said output terminals, the four branches BIp, BQp and BIn and BQn each including at least an impedance, respectively RIp, RQp, RIn, RQn, having identical characteristics. Mixer circuits can be easily stacked with this signal processing circuit.

Abstract: Disclosed herein is a power supply adapter for supplying DC power to a broadcast receiver that processes a broadcast signal. The power supply adapter includes: a converter configured to generate the DC power from AC power; a broadcast signal reception section configured to receive the broadcast signal; a mixer configured to mix the broadcast signal received by the broadcast signal reception section with an output from the converter; and a supply section configured to supply an output from the mixer to the broadcast receiver.

Abstract: A pre-emphasis circuit and methods are provided. The circuit includes a first amplifier and a second amplifier. The first amplifier contains M first driver cells and is operable to amplify a signal. The second amplifier contains P second driver cells and is operable to amplify a delayed version of the signal The pre-emphasis circuit further includes logic circuit operable to change a pre-emphasis ratio of the pre-emphasis circuit including switching off one or more of the M first driver cells of the first amplifier and switching on a corresponding one or more of the P second driver cells of the second amplifier, such that a swing amplitude for an output signal provided by the pre-emphasis circuit is maintained at a constant level.

Abstract: A rebroadcasting apparatus for mobile media includes a receiving antenna and a transmitting antenna. The signal to be rebroadcast is received with a circularly polarized directional antenna. The transmitting antenna has circular polarization opposite to the polarization of the receiving antenna. Amplifiers and filters may be included between receiving and transmitting antennas to regulate retransmitted signal quality. The transmitting antenna uses one or more bays of quasi-helical dipole radiators excited using manifold feed equipped with tuning paddles. The transmitting antenna may be formed from light-weight sheet metal or other readily mass-produced materials. The transmitting antenna may be housed within an ordinary security camera enclosure or similar radio-transparent housing.

Abstract: Switched-mode amplifiers and devices having such amplifiers include quadrature pulse-width modulation that is based on Cartesian (as opposed to polar) coordinates. Two sets of pulses that represent respective in-phase and quadrature components of a conventional cartesian-coordinates input signal can be combined such that the combined set of pulses can be provided to a switched-mode amplifier without nonlinear cartesian-to-polar transformation and its associated wider internal bandwidth and other problems.

Abstract: A method and apparatus is presented for actively signal splitting an RF signal. Specifically, the RF signal is frequency-separated to generate a first signal including a first set of frequencies and a second signal including a second set of frequencies. The first and second signals are independently amplified to generate first and second amplified signals, respectively. The first and second amplified signals are then combined to generate a recombined signal. The recombined signal is divided to generate first and second splitter output signals.

Abstract: A method performed by a receiver is provided. The method includes generating an RDS/RBDS candidate codeword from a set of RDS/RBDS symbols where the RDS/RBDS candidate codeword has a subset of RDS/RBDS values that differs from corresponding subsets of RDS/RBDS values in all other possible RDS/RBDS codewords and determining whether the RDS/RBDS candidate codeword meets an acceptance criterion by comparing a first subset of reliability values determined from the set of RDS/RBDS symbols and having signs that differ from corresponding signs in the subset of RDS/RBDS values with a second subset of reliability values determined from the set of RDS/RBDS symbols and mutually exclusive with the first subset of the reliability values. A first number of values in the first and the second subsets of reliability values is less than a second number of values in the RDS/RBDS candidate codeword.

Abstract: An amplifier has a band pass response. The band pass response may be set by setting corner frequencies of low pass filters.

Abstract: An RF circuit module, in which a power amplifier and a transceiver are united, with reduced interference between its electronic circuit blocks, downsized and still having high performance, and with a stable performance not dependent on the ground land structure on the motherboard, is provided. The ground plane 110 for at least a last-stage amplifier 11 of the power amplifier 10 where the greatest power is generated in the whole RF circuit block, that is, the source of generating the greatest noise and heat for the RF circuit block, is isolated from the ground plane for at least one circuit portion of the transceiver 9 including an LNA 51, receiver 52, transmitter 30, and VCO 70. These ground planes are connected to a common ground plane 480 through different connection conductors, respectively.

Abstract: A receiver includes a common-gate low noise amplifier (LNA) configured to receive an RF input signal and produce an amplified RF signal. A down-converting passive mixer is configured to mix the amplified received RF input signal with a local oscillator signal generated by a local oscillator to generate a down-converted amplified signal. An amplifier is configured to amplify the down-converted signal and has an input impedances in on the order of ohms. Only a single LNA may be required to receive RF inputs in all frequency bands of a multi-band communication standard.

Abstract: A low-noise amplification apparatus and method in a receiver in a wireless communication system are provided, in which a main amplifier amplifies a received signal, a sub-amplifier amplifies a third-order harmonic component more strongly than a signal component in the received signal and cancels the third-order harmonic component by combining the amplified signal with the signal received from the main amplifier. A noise eliminator amplifies noise included in the received signal and eliminates the noise by combining the amplified noise with the signal received from the main amplifier or the signal received from the sub-amplifier.

Abstract: A supply voltage controlled power amplifier that comprises a power amplifier, a closed power control feedback loop configured to generate a power control signal, and a dual voltage regulator coupled to the power control feedback loop, the dual voltage regulator comprising a first regulator stage and a second regulator stage, wherein the closed power control loop minimizes noise generated by the first regulator stage.

Abstract: A radio receiver includes a low-noise amplifier, pulse-to-signal conversion module, and intermediate frequency stage. The low-noise amplifier is operably coupled to receive and amplify an M-bit signal at a radio frequency. The M-bit signal at a radio frequency is representative of a pulse signal that is carried on a radio frequency. The pulse-to-signal conversion module demodulates the M-bit signal to produce an N-bit signal at an intermediate frequency. For example, the pulse-to-signal conversion module performs pulse-width demodulation, pulse-density demodulation, or pulse-position demodulation to recapture the N-bit signal. The intermediate frequency stage steps down the frequency of the N-bit signal to produce a base-band digital signal.

Abstract: A power amplifier has a non-linear low power pre-distortion amplifier (112) for transforming a carrier signal (111) to a pre-distorted signal (113) having a carrier component with out-of-phase non-linear distortions, and a non-linear power amplifier (114) having non-linear characteristics similar to a portion of the non-linear low power pre-distortion amplifier for generating from the pre-distorted signal a transmission signal (115) having an amplified carrier component with substantially diminished non-linear distortions.

Abstract: An amplifier assembly receives an input signal including multiple frequency channels. A first stage amplifier amplifies the input signal, to produce at an output thereof an amplified first signal including the multiple frequency channels. A plurality of second stage amplifiers have their respective inputs coupled to an output of the first stage amplifier. Each second stage amplifier amplifies the amplified first signal, to produce at its respective output a respective second amplified signal including the multiple frequency channels. The first stage amplifier and the second stage amplifiers are variable gain amplifiers, and are constructed on a common Integrated Circuit (IC) substrate.

Abstract: An embodiment of the present invention provides an apparatus, comprising an integrated circuit, wherein a first portion of the integrated circuit is placed on a top tier substrate and a second portion of the integrated circuit is placed on a bottom tier substrate stacked adjacent the top tier substrate and wherein the first portion and the second portion of the integrated circuit are interconnected; and printed spiral arms stacked vertically on both the top and bottom surface of the top tier substrate thereby creating high Q inductors.

Abstract: RF power detector employing an envelope amplifier circuit and a current mirror circuit. The output of the current mirror circuit supplies a bias voltage for biasing the output of the envelope amplifier circuit. Furthermore, the output of the envelope amplifier circuit is fed back to the output of the current mirror circuit so as to reduce the magnitude of the bias signal according to the magnitude of the amplified RF signal envelope. In this manner, the overall gain of the RF power detector can be selectively reduced, resulting in an RF power detector having a more linearized dynamic range and greater ability to compensate for variation in gain caused by temperature.

Abstract: The present invention is to provide a technique which optimizes a gate resistor of a bias circuit to thereby make it possible to greatly improve a distortion characteristic of a power amplifier. A bias circuit used as for biasing the gate of a final-stage power transistor is included in a power amplifier provided in a communication mobile system. In the bias circuit, an inductance and a resistor are series-connected between a power supply voltage and the gate of the power transistor. The resistance value of the resistor is set to approximately the same order as an input impedance of the power transistor. When the input impedance of the power transistor is about 10? or so, for example, the resistor is set to about a few ? to about 100?. Thus, the gain of the power transistor at a low-frequency band can greatly be suppressed.

Abstract: A DC-offset cancellation system for a wireless receiver is disclosed. The DC-offset cancellation system comprises an amplifier and an impedance inverter configured to transform inductance applied to a received signal to a capacitance.

Abstract: A receiver circuit is disclosed which enables a reception signal fed into the receiver circuit by a reception element to be processed—e.g. amplified—with little to no errors. The receiver circuit has a cascode circuit on an input side, which cascode circuit generates an output signal from the reception signal of the reception element. Control means that act on the cascode circuit are connected to the cascode circuit. The control means are configured in such a way that they counteract an increase in a high level of the output signal of the cascode circuit on account of an excessively large input signal from the reception element.

Abstract: A radio frequency (RF) receiver front-end includes an low noise amplifier (LNA) module, a current domain mixing module, and a buffer module. The LNA module is coupled to amplify an inbound RF signal to produce an amplified inbound RF current signal. The current domain mixing module is coupled to mix the amplified inbound RF current signal with a local oscillation to produce a mixed current signal. The buffer module is coupled to provide a baseband or near baseband voltage signal from the mixed current signal.

Abstract: An amplifier includes an amplification unit which amplify a first difference between first and second input signals, a second difference between second and third input signals and a third difference between third and first input signals by a differential mode gain, and amplify an average of the first, second and third input signal by a common mode gain, for outputting a first output signal corresponding to a sum of the amplified first difference and the amplified average, a second output signal corresponding to a sum of the amplified second difference and the amplified average, and a third output signal corresponding to a sum of the amplified third difference and amplified average; first, second; and a reduction circuit which reduces the common mode gain less than the differential mode gain.

Abstract: An apparatus for calibrating gain of an radio frequency receiver (“Rx”) is disclosed to provide, among other things, a structure for performing in-situ gain calibration of an RF integrated circuit over time and/or over temperature without removing the RF integrated circuit from its operational configuration, especially when the gain of the RF integrated circuit is susceptible to variations in process, such as inherent with the CMOS process. In one embodiment, an exemplary apparatus includes a thermal noise generator configured to generate thermal noise as a calibrating signal into an input of an Rx path of an RF integrated circuit. The apparatus also includes a calibrator configured to first measure an output signal from an output of the Rx path, and then adjust a gain of the Rx path based on the thermal noise. In one embodiment, the thermal noise generator further includes a termination resistance and/or impedance.

Abstract: An audio communication unit comprises a receiver for receiving an audio signal, a sigma-delta modulator operably coupled to the receiver and arranged to modulate the received audio signal, and a class-D amplifier stage operably coupled to the sigma-delta modulator and arranged to amplify the modulated received audio signal. One or more feedback path(s) is/are arranged from an output of the class-D amplifier stage to the sigma-delta modulator. The provision of one or more feedback path(s) from the output of the class-D audio amplifier to the sigma-delta modulator facilitates smaller die size; higher power efficiency and power supply rejection ratio/intermodulation cancellation performance.

Abstract: There is provided a method for use in a wireless communication to avoid detection of a false modulated signal in a paged device. In one embodiment, a modulated signal is received by the paged device. Then, the modulated signal is identified by the paged device as a preliminary false modulated signal. Thereafter, the gain of at least one paged device amplifier and/or a matching threshold of the paged device is reduced by the paged device to decrease a sensitivity of the paged device to avoid detection of a future false modulated signal. In one embodiment, the wireless communication is a Bluetooth wireless communication and the paged device is a Bluetooth enabled device. An exemplary system for implementing one embodiment of the disclosed method is described.

Abstract: Embodiments of the present general inventive concept include a low noise amplifier and method with an improved linearity while reducing a noise disadvantage (e.g., increase). One embodiment of a low noise amplifier can include a first transistor to receive an input signal at a control terminal thereof, a second transistor having a first terminal coupled to a second terminal of the first transistor, an envelope detector to output a control signal corresponding to a characteristic of the input signal and an envelope amplifier to amplify the control signal to be applied to a control terminal of the second transistor.

Abstract: Methods and apparatus to perform radio frequency (RF) analog-to-digital conversion are described. According to one example, a receiver includes an amplifier to amplify received analog RF signals and a mixer-free circuit for converting the received analog RF signals to digital signals.

Abstract: A radio-frequency receiver for, e.g., receiving GPS signals in a cellular telephone has an input, a first gain stage in the form of a linear low noise amplifier with voltage-voltage feedback and a resonant load, and a second gain stage based on a common source input transconductor. Associated with the input and the first gain stage is a filter comprising a notch filter part for rejecting an interfering signal, e.g. a cell phone transmitter signal, and, connected between the parallel resonant circuit and the input, a series capacitance which, in combination with the inductor of the parallel-resonant circuit, forms a series-resonant circuit to provide a low impedance path at a wanted signal frequency.

Abstract: A system and a method create a pre-distorted signal y(k) from an interpolated broadband baseband signal x(k) for a transmitter power amplifier having at least three branches to which the signal x(k) is respectively connected on the input side. A first branch contains a distortion device for taking into account memory effects of the transmitter power amplifier to which the signal x(k) is supplied on the input side. Where 2=j=n, each other j-th branch contains the following serially mounted elements: a deceleration device with a signal x(k) supplied on the input side, a first adder, a digital low-pass filter, and a second adder, the output signal formed by the second adder being used to create the pre-distorted signal y(k). The distortion device pertaining to the first branch is connected, on the input side, to another input of the second adder of the second branch, and on the output side, to another input of the first adder of the second branch.

Abstract: A first signal conditioning circuit is formed from a first portion, a second portion and a third portion. Signal conditioning functions of each of these portions are facilitated by a predetermined type of integrated semiconductor die within which they are formed. Two different semiconductor dies are thus provided for facilitating integration of the first through third signal conditioning portions therein. Wire bonds are provided between the two different semiconductor dies in order to form circuit paths between the different first through third portions. The signal routing using between the two different semiconductor dies provides for completing of the first signal conditioning circuit having a first signal conditioning function. For example, circuits such as interstage matching circuits are disposed on a different semiconductor die than power amplifier circuits.

Abstract: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation.

Abstract: To provide an antenna device adapted to interrupt jamming waves and enable cost reduction, a high-pass filter (HPF) adapted to interrupt general-use frequencies at least near a low-frequency side of a pass band intended for use is provided as a frequency selection circuit 11A on the antenna 1 side in an initial-stage LNA 2A. By setting a low-side cutoff frequency to 900 MHz, it is possible to prevent reception of frequencies in a general-use frequency band with a high frequency of use as jamming waves. That is, for example, it is possible to prevent reception of frequencies in 800 to 900 MHz band for mobile cellular telephones and higher harmonics thereof as jamming waves. Further, since an additional filter is not required in the antenna device, the circuit structure can be simplified.

Abstract: An amplifier module for radio frequency signal circuits includes an electrically conductive housing. Two coax connectors are electrically linked to an amplifier circuit contained within the module. A separate transformer is external to the module. Both the module and the external transformer are mountable to a chassis frame. Other modules are usable in the system in addition to the amplifier module. The transformer can be wall mounted to the chassis frame, or the transformer can be internal to a module which also mounts to the chassis frame.

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.