Abstract: A feedforward amplifier circuit (30) compensates for distortion introduced into an amplified input carrier signal (34) by amplifying and feedforwarding a distortion signal component from one or more of the amplifiers (32a-32n) in an amplifier array (32) used to amplify the input carrier signal (34). Specifically, a main power amplifier (31) includes a plurality of combined power amplifiers (32a-32n) for amplifying the input carrier signal (34) to create an amplified carrier signal with a carrier signal component and a distortion signal component. The amplified carrier signal (34) is amplified on a main output path.

Abstract: A feed forward amplifier network (100) employs a method (300) and apparatus for providing carrier cancellation in a feed forward amplifier circuit (101). A modulator (118, 120) modulates (303) an input signal (141) of the amplifier circuit (101) with a reference modulation based on a reference signal (143, 145) and a control signal (153, 155). The amplifier circuit (101) amplifies (305) the modulated signal, introducing nonlinear distortion in the process. A modulation determination circuit (107, 109, 115) determines (307) the reference modulation in the amplified signal and provides a determined signal to an adjustment circuit (105). A residual modulation detection circuit (139, 125, 127, 129) demodulates (313) the determined modulation to recover any residual modulation remaining in the determined signal and adjusts (317) the control signal (153, 155) to reduce the recovered residual modulation and to produce carrier cancellation in the determined signal.

Abstract: The present invention is intended to provide a feedforward amplifier circuitry which is capable of changing a location or placement of each section constituting the feedforward circuitry, in particular a feedforward amplifier circuitry which is capable of changing an interposing location of a variable phase shifter. In the feedforward amplifier circuitry, a variable phase shifters (5, 12) can be disposed on a location other than a post-stage of a predistortion circuits (3, 20), as a result of which it is advantageously possible to provide a designer with more flexibility in changing the locations of variable shifters, regardless of the conventional arrangement of the variable phase shifters disposed on the post-stages of the distortion circuits, when the feedforward amplifier is actually designed.

Abstract: An amplifier is described having an amplification stage in a first feedback loop. The amplification stage is operable to open the first feedback loop during operation of the amplifier. The amplifier further comprises a feed forward path bypassing the amplification stage. The feed forward path is operable to provide a second feedback loop when the first feedback loop is open.

Abstract: An in-band group delay equalizer is formed in a simple circuit configuration so as to have a flat group delay characteristic over a wide frequency band without having a peak of group delay near each passband edge. The in-band group delay equalizer includes a plurality of convex group delay circuits. Each convex group delay circuit is formed of one hybrid coupler and two resonators connected to respective divided output ports of the hybrid coupler. The center frequencies of the respective convex group delay circuits are set to be different from each other so that the overall group delay characteristic of the in-band group delay equalizer becomes flat. The bandwidth and the group delay can be easily adjusted.

Abstract: Signal handling equipment, such as a high power amplifier, is implemented with feed-forward compensation circuitry that adjusts the effective operation of the equipment (e.g., linearizes the amplifier). The compensation circuitry includes (i) a nulling loop, which generates an error signal based on the output from the amplifier, and (ii) an error loop, which generates, based on the error signal, a feed-forward compensation signal that is added to the output of the amplifier. The compensation circuitry is tuned by tuning the nulling loop and then iteratively tuning the error loop based on data generated by perturbing the tuning of the nulling loop. In one implementation, data corresponding to the amplitude of the output signal is analyzed to generate metric values that are used to iteratively adjust the tuning of the error loop.

Abstract: An apparatus and method for operating an adaptive circuit includes injecting a set of orthogonal tracer signals into the circuit. The tracers signals are extracted after modification by at least a portion of the circuit and are examined by respective controllers to modify operation of the circuit. In one embodiment, the invention is incorporated into a feed forward amplifier where a set of orthogonal tracer signals are injected into the amplifier. A detector controller detects the orthogonal tracer signals, as modified by portions of the amplifier, and applies each tracer signal to a respective controller. Each controller examines its respective signal and modifies its output to control a portion of the amplifier accordingly. The controllers apply their outputs to the respective portions of the amplifier at substantially the same time, leading to quick convergence of the operating point of the amplifier to an optimal or near-optimal configuration.

Abstract: An amplifier arrangement comprises an active amplification element arranged between a first and a second contact within a first signal path. A signal fed in at the first contact is amplified in the amplification element. Furthermore, a controller for a variably operation of the amplification element, as well as a passive second signal path. The second signal path, which is arranged parallel with the first signal path and bypasses the first signal path, is also contained therein. An ultrasound device contains such an amplifier arrangement.

Abstract: A distortion reduction system uses upstream signal information, such as the carrier frequencies in an input signal, to adjust at least one frequency for a pilot signal to be injected into the distortion reduction system and to be detected at the output of the distortion reduction system, thereby enabling improved distortion reduction of changing input signals. For example, processing circuitry obtains the traffic frequencies making up a signal to be amplified by a feed forward arrangement. Using the traffic frequencies, the processing circuitry determines at least one frequency for a pilot signal, and the processing circuitry tunes a pilot signal generator to the at least one frequency for the pilot signal. The feed forward arrangement receives the signal to be amplified and provides replicas of the signal on a main signal path and on a feed forward path. The pilot signal is injected into the main signal path at the at least one frequency along with the signal to be amplified.

Abstract: A delay circuit for the secondary path of a feed-forward high power amplifier is disclosed. A first 3 dB quadrature hybrid coupler is coupled to first and second resonator circuits that each includes a varactor circuit and are resonant at a first resonant frequency. The output of the first hybrid coupler is coupled to the input of a second 3 dB quadrature hybrid coupler. The second hybrid coupler is coupled to third and fourth resonator circuits that each includes a varactor circuit and are resonant at a second resonant frequency that is greater than the first resonant frequency. The overall combined delay response of the first hybrid coupler and the second hybrid coupler appearing at the fourth node of the second hybrid coupler is substantially constant between the first resonant frequency and the second resonant frequency.

Abstract: A method of setting up a linearizing circuit such as a linear power amplifier is described. According to the method, an input signal is supplied at a low, starting power level and is lowly increased during a set-up until it attains an operational level for normal use. The advantage of this is that pilot tone used in the linearizing circuit can be readily detected during set-up because its amplitude is above that of the low, starting power level of the input signal. A feed-forward linearizing system and a transmission system utilizing the technique are described.

Abstract: A system and method for compensating switched mode amplifiers. The amplifier system includes an adaptive filter coupled to the output of circuitry that recovers the analog signal from the output of the switching amplifier circuitry. The adaptive filter derives an inverse transfer function of the forward path through the system. The derived inverse transfer function is used to generate a coefficient map which a compensation filter responsively compensates for from variations in the output load of the amplifier system. In the disclosed method, the deriving the inverse transfer function may further include calibrating the adaptive filter continuously, at system startup or in response to user demand.

Abstract: There is provided a transmitter, and a method using such a transmitter, the transmitter having an amplifier for amplifying a received signal, predistortion means for predistorting a received signal prior to the signal passing through the amplifier means, a transmitter for transmitting a signal, and a control for controlling the transmitted. If the power level of the signal to be transmitted by the transmitter is below a predetermined level, the signal is not predistorteded by the predistortion means and if the power level of the signal to be transmitted by the transmitter is above a predetermined level the received signal passes through the predistortion means and amplifier.

Abstract: Disclosed is a predistorter for preliminarily compensating a distortion caused in a circuit comprising a modulator, a variable gain amplifier, and a non-linear amplifier, the predistorter comprising: an amplitude detector for detecting an amplitude of an input signal; a gain detector for detecting a gain of the variable gain amplifier; a first multiplier for multiplying the amplitude of the input signal with the gain of the variable gain to output a product therebetween; a generator for generating a predistortion function corresponding to the product; and a second multiplier for multiplying the input signal with the predistortion function to output a product therebetween to the modulator.

Abstract: An impedance matching low noise amplifier (“LNA”) having a bypass switch includes an amplification circuit, a bypass switching network and a match adjustment circuit. The amplification circuit has an amplifier input and an amplifier output, and is configured to receive a radio frequency (RF) input signal at the amplifier input and apply a gain to generate an amplified RF output signal at the amplifier output. The bypass switching network is coupled to a low-gain control signal and is also coupled between the amplifier input and the amplifier output. The bypass switching network is configured to couple the amplifier input to the amplifier output when the low-gain control signal is enabled in order to feed the RF input signal through to the RF output signal. The match adjustment circuit is coupled to the low-gain control signal and the RF input signal, and is configured to couple the RF input signal to an impedance when the low-gain control signal is enabled.

Abstract: Provided is a distortion-compensated amplifying circuit capable of suppressing distortion without attenuating a level of carrier components, and further obtaining a larger amount of suppression of distortion, which has not been achievable by conventional distortion-compensated amplifying circuit using a pre-distortion technique. A balanced type amplifying circuit is structured such that amplifiers 115 and 116 placed in parallel are sandwiched by 90-degree hybrid circuits 114 and 117. The 90-degree hybrid circuit 114 is supplied with an original signal including carrier components and a distortion signal including distortion equal in amplitude and opposite in phase (having a phase difference of 180 degrees) to distortion that occurs when the original signal is amplified by the amplifiers 115 and 116. The 90-degree hybrid circuit 114 performs a process of differential amplification with a phase difference of 180 degrees between the original signal and the distortion signal.

Abstract: An RF power amplifier with amplifier stage failure detection comprises an amplifier input for receiving an RF signal to be amplified, an amplifier output for outputting an amplified RF signal, a plurality of separate amplifier stages coupled between the amplifier input and amplifier output so as to cumulatively provide a desired amplifier gain to the input RF signal, and means for detecting amplifier stage failure by providing a pilot tone separately to the amplifier stages based on a separate timing for each stage and detecting pilot tones output from the stages based on the timing.

Abstract: The present invention provides a slope equalizer for use in a voice frequency channel card, which is preferably electronically and remotely controllable, and retrocompatible with existing telecommunication systems. The slope equalizer of the invention includes a high-pass filter followed by a variable gain stage amplifier, where the variable gain stage amplifier is an operational amplifier with a plurality of parallel input signal paths, each of the signal paths being a series-connected resistor and switch. The switch is preferably a FET transistor that is electronically and, optionally, remotely controllable. The circuit topology allows the use of FET transistors having relatively high on-resistances. A further advantage of the topology is that the FET switches are connected to a virtual ground by way of an operational amplifier, thereby reducing on-resistance modulation caused by signal variations across the FET.

Abstract: The input signal (110) to a non-linear amplifier (112) is predistorted by injecting a correction signal at coupler (124). To generate the correction signal, a sample of the input signal is amplified using amplifier (130) which has substantially the same distortion generating characteristics as amplifier (112). The output of amplifier (130) is sampled, and the main tone energy is removed at (138), leaving the correction signal for injection to the main signal path. The main portion of the output of amplifier (130) is added coherently to the output of amplifier (112) to enhance efficiency. The correction signal can be manipulated to correct distortion in the output of combiner (152) due to the main portion of the output of amplifier (130).

Abstract: A linear power amplifying apparatus is disclosed. In case where the phases of the signal amplified in the main amplifier and of the input signal are compared, the amplified signal and the input signal are distributed and then coupled with a predetermined phase difference, thereby reducing the error component and widening the tolerance band which can attenuate the carrier as much as desired, so that the phase controlling for carrier attenuation is facilitated. In addition, in case where the phase of the error signal amplified in the error amplifier and that of the input signal amplified in the main amplifier are compared, the error signal and the input signal are distributed and then coupled with a predetermined phase difference, thereby reducing the error component and widening the tolerance band which can attenuate the error as much as desired, so that the phase controlling for error attenuation is facilitated.

Abstract: The Reflect Forward Adaptive Linearizer Amplifier (RFAL Amplifier) assembly (15) in FIG. 1 provides a linerizing method that uses the input reflected signal of the Main 1 Amplifier (23) to develop an intermodulation-correcting signal. The invention incorporates a directional coupler at the input of the Main 1 amplifier that samples and sums the input reflected signal from the Main 1 Amplifier and the forward fundamental input signal to form a distortion-correcting signal that contains both the fundamental and the distortion products of the output. By proper delay and amplification of this correcting signal, it can then be used to drive another Main amplifier (35) to both cancel the output distortion products and double the output power of the Main 1 Amplifier with significant improvement of the overall linearity and efficiency of the final amplifier assembly. The technique allows the use of lower cost transistor up to the Pout at the 1-dB Gain Compression Point with significant distortion cancellation.

Abstract: A feedforward amplifier (150) according to the present invention uses a direct coupling of an amplifier stage (158) with the amplifier's load (RL). The main amplifier (202) is coupled through a transmission line (210) to the load. This direct coupled amplifier stage (158) is driven by a signal that induces a very low impedance in parallel with the load to the error signal, but appears as an open circuit to the desired signal so that the desired signal from the main amplifier is substantially unaffected.

Abstract: A compensated three stage amplifier having high gain as well as high speed is disclosed. The amplifier comprises a NMC and NGCC compensated cascaded three stage amplifier for receiving an input signal and for providing an amplified output signal in dependence thereupon. An extra feed forward transconductance stage extending from the input port of a first gain stage to the output port of a second gain stage of the amplifier is used in order to cancel one of two non-dominant poles in the transfer function of the amplifier with the additional zero introduced by the extra signal path. This results in a transfer function for a three stage cascaded amplifier having only two poles, which is highly desirable by allowing design of such amplifiers providing stable operation at high gain as well as high speed.

Abstract: A radio frequency signal output module having a power amplifier and an isolator element is provided in which a radio-frequency output stage can be largely reduced in size and thickness. The radio frequency signal output module comprises a dielectric multilayer substrate; a radio-frequency power amplifier circuit; an isolator element; an impedance matching circuit which is inserted and connected between the radio-frequency power amplifier circuit and the isolator element; and a feedback loop for controlling the gain of the radio-frequency power amplifier circuit. The radio-frequency power amplifier circuit, the isolator element, the impedance matching circuit, and the feedback loop are integrally mounted on the dielectric multilayer substrate, and the feedback loop is branched from the impedance matching circuit, and connected to the radio-frequency power amplifier circuit.

Abstract: A feedforward amplifier combines an input signal combined by a first error rejection loop with an error component and a first pilot signal detected by a second error detection loop, thereby canceling out the error component and the first pilot signal residual in the input signal.

Abstract: In a feedforward amplifier with a dual loop in which a distortion injection path of a distortion elimination circuit 50 is provided as a feedforward configuration composed of a first auxiliary amplifier distortion elimination circuit 60 and a first auxiliary amplifier distortion elimination circuit, a second variable attenuator 55 and a second variable phase shifter 56 are provided preceding the distortion detection circuit 60, a second pilot signal injected between stages of a main amplifier 14 is detected by a directional coupler 85, and the second variable attenuator 55 and the second variable phase shifter 56 are controlled by a second controller 97 to minimize the level of the detected second pilot signal, thereby bringing the distortion elimination circuit and the first auxiliary distortion detection circuit into balance at the same time.

Abstract: An RF power amplifier with amplifier stage failure detection comprises an amplifier input for receiving an RF signal to be amplified, an amplifier output for outputting an amplified RF signal, a plurality of separate amplifier stages coupled between the amplifier input and amplifier output so as to cumulatively provide a desired amplifier gain to the input RF signal, and means for detecting amplifier stage failure by providing a pilot tone to the amplifier stages, duty cycling the amplifier stages based on a separate timing for each stage and detecting the pilot tone output from the stages based on the timing.

Abstract: A feedforward amplifier and notch filter (150) according to the present invention uses a direct coupling of an amplifier stage (158) with the amplifier's load (RL). The main amplifier (202) is coupled through a transmission line (210) to the load. This direct coupled amplifier stage (158) is driven by an signal that induces a very low impedance in parallel with the load at the receive frequency, but appears as an open circuit at the desired frequencies so that the desired signal from the main amplifier is virtually unaffected while output components at the receive frequency are cancelled.

Abstract: A pilot adjusting system adjusts the power level of the pilot relative to the power level of the input signal. For example, the pilot adjusting system detects the power level of the input signal on the signal path leading to an RF amplifier. In response to the power level of the input signal, the pilot adjusting system adjusts the power level of the pilot signal which is injected into the signal path prior to the RF amplifier. In certain embodiments, the pilot adjuster adjusts the pilot power level to maintain a desired input signal to pilot signal ratio at the input to the RF amplifier for the input signal range of the RF amplifier. As such, if the input signal power level drops 30 dB, the pilot adjuster reduces the power level of the pilot signal by 30 dB, thereby maintaining the input signal to pilot ratio throughout the input range of the RF amplifier.

Abstract: The present invention relates to a linear amplifier for amplifying power of a radio-frequency signal whose level varies widely, based on feed-forward technique. The linear amplifier according to the present invention is given in advance appropriate transfer characteristics for an error elimination loop and an error detection loop and these appropriate transfer characteristics are applied at a starting time. Therefore, performance and total reliability of equipment to which the present invention is applied are enhanced and cost reduction thereof is realized.

Abstract: A distortion compensation amplifier has a distortion detection loop that divides an input signal, amplifies one divided signal with an amplifier and uses the amplified signal and another divided signal to detect a distortion component generated and introduced into the amplified signal in the amplifier and a distortion removal loop that removes the detected distortion component from the amplified signal produced by the amplifier. The distortion detection loop comprises filter means for reducing the distortion component of the amplified signal output by the amplifier that was generated and introduced into the amplified signal in the amplifier and detects the distortion component reduced by the filter means. The distortion removal loop removes from the amplified signal the detected distortion component that was produced by the amplifier and reduced by the filter means.

Abstract: A feedforward amplifier has

Abstract: A feed forward type distortion compensation amplification apparatus includes a first division unit for dividing an input signal into a first channel signal and a second channel signal, a main amplifier for amplifying the first channel signal, a variable attenuation unit for processing the second channel signal to provide an amplitude adjusted second channel signal, a delay unit for delaying the amplitude adjusted second channel signal, a second division unit for dividing an output signal of the main amplifier into a third channel signal and a fourth channel signal and subtracting one of the third channel signal and the delayed second channel signal from the other to extract a distortion component introduced by the main amplifier, and a distortion compensation unit for removing a distortion component introduced into the fourth channel signal by the main amplifier, by using the distortion component extracted by the second division unit.

Abstract: The invention relates to a low cost feed forward RF power amplifier arrangement for amplifying an RF input signal using a main power amplifier operating as a class A/B amplifier. The method and apparatus modify the input signal to the main amplifier to compensate for the distortion added by the main power amplifier. The circuit provides for injecting a delayed version of the input signal, through a fixed gain-phase circuity, at a point whereby the resulting signal is amplified by the error amplifier of the second loop. A digitally controlled processor iteratively modifies various phase and gain controls to adjust the output of the amplifier. Different gain and phase control lines are iteratively updated at different rates.

Abstract: A radio communication device has a first variable power amplifier 19 and a second variable power amplifier 20 and performs gain control of the variable power amplifiers 19 and 20 by a variable power amplifier control section 27 for controlling transmission power of the radio communication device. At this time, the variable power amplifiers 19 and 20 are switched on and off under the control of a switch control section 25 in response to the theoretical value of transmission power updated based on the transmission power of the radio communication device detected by a transmission power detection section 24 or a transmission power control bit extracted by a base band signal processing section 16 for prolonging the time period over which the variable power amplifier 19 or 20 is off.

Abstract: A group delay adjusting circuit. The group delay adjusting circuit comprises an electronically adjustable variable capacitance, and an electronically variable virtual inductor coupled in parallel to the electronically variable capacitance at a node.

Abstract: A feedforward amplifier is linearized by adapting off the detection of an applied modulation source. The feedforward amplifier has two loops: a first loop and a second loop. Modulators in the two loops are adjusted by controllers that adapt in response to detection of the modulation source injected into the first loop.

Abstract: A power amplifier having a predistortion linearizer for improving the non-linear property of the power amplifier is disclosed. The powers amplifier includes a predistorter for outputting a distortion compensating signal to the high power amplifier, a delay line for delaying an input signal for a prescribed period of time and outputting a reference signal, a distortion component detection circuit for detecting a distortion component by comparing the output signal of the power amplifier with the reference signal of the delay line, and an adaptive controller for controlling the properties of the predistorter in order to minimize the detected distortion component.

Abstract: A apparatus for providing a waveform as a switched input into an output matching network of a standard class E amplifier. The apparatus includes a switch in communication with the input and the combining device receiving amplitude and phase information from the primary waveform. The combining device functions to combine the amplitude and phase information to create a control signal which is used to control the switch and create a secondary waveform for input to the matching network. In this way, an amplitude modulated waveform is amplified at high efficiency, enabling application of either all or part of the phase and/or amplitude modulation at the input of the amplifier.

Abstract: A low noise amplifier (10) having an amplifier mode and a bypass mode. In the amplifier mode the input signal received at an input terminal (12) is amplified by an amplifying transistor (40) and the output signal supplied at an output terminal (50). In the bypass mode the input signal is not amplified, but transferred by a bypass circuit (22) from the base to the collector of the amplifying transistor. An input impedance matching circuit (14) and an output impedance matching circuit (44), along with the bypass circuit (22) provide a constant input and output impedance when the low noise amplifier (10) operates in the amplifier mode and the bypass mode.

Abstract: An amplifier linearizer circuit has a signal cancellation circuit including a signal adjuster having M branch signals (M≧1), and a distortion cancellation circuit including a signal adjuster having N branch signals (N≧1). The linearizer has a controller for adaptively controlling the M-branch and N-branch signal adjusters. The controller has only one monitor receiver to monitor the M branch signals and only one monitor receiver to monitor the N branch signals.

Abstract: A feed-forward amplifier configuration 40n having a distortion detector circuit and a distortion canceller circuit is formed between an input port Ipn and an output port OPn of a multi-terminal power-combining power amplifier with a main amplifier 4M provided for each channel between an input-side multi-terminal power combiner 3 and an output-side multi-terminal power combiner 5.

Abstract: (Object)

Abstract: A method of controlling a feedforward distortion compensation amplifier has steps of

Abstract: A feedforward amplifier is provided that divides a signal to be amplified, amplifies one divided signal with a main amplifier, combines the amplified signal and another divided signal to detect distortion components generated in the main amplifier and contained in the amplified signal, amplifies the detected distortion components with an auxiliary amplifier, and combines the amplified distortion components and the amplified signal from the main amplifier to remove those of the distortion components present in a prescribed band from the amplified signal. The feedforward amplifier includes a filter, typically installed ahead of the auxiliary amplifier, that reduces out-of-prescribed-band components contained in the detected distortion components, thereby improving the characteristic of the out-of-prescribed-band noise.

Abstract: A delay circuit in which amplitude characteristic and delay time characteristic of the output signals do not have any ripple relative to the length of the transmission line is provided. The delay circuit includes a circuit that makes a part of signals distributed into two parts by the power divider (103) to be identical in amplitude and inverse in phase relative to the component of signals outputted from the terminal-a directly to the terminal-c of the circulator (104). By composing with the power combiner (107) both signals are offset each other at the output terminal. As a result, only the signals that are inputted from the input terminal (101) and transmitted through the circulator (104) and the open-ended transmission line (105) are outputted to the output terminal (102).

Abstract: A hybrid multicarrier RF power amplifier linearization architecture combines ACT and feed-forward amplifier stages to achieve high output distortion rejection and enhanced amplifier linearity. A carrier cancellation loop is coupled with a main RF power amplifier stage having parallel RF power amplifiers coupled via intermod-complementing predistortion paths. The carrier cancellation loop is coupled to a feed-forward loop containing a feed-forward RF power amplifier, to produce a composite amplified output signal having very reduced intermodulation products. Vector modulators in the main amplifier and feed-forward amplifier stages are controlled by a digital signal processor, using outputs from various monitoring subsystems, including pilot tone detection, correlator, distortion and power detector circuits.

Abstract: There is disclosed a linearizer in which a main signal inputted to a main amplifier is orthogonally modulated by an orthogonal modulator to allow an upper side band signal or a lower side band signal to appear, the signal is used to perform a distortion compensation control, and a constitution of a side band signal detector is thereby simplified. When a phase of a base band signal from a modulated signal generator is reversed in time division, an appearance position of the side band signal is changed to a lower side from an upper side, or to an upper side from a lower side. Moreover, when the phase of the base band signal is changed at high speed, an amplification property is controlled at high speed.

Abstract: A method and apparatus for utilizing the distortion generated within a portion of a balanced amplifier to cancel the distortion generated within the whole balanced amplifier. Samples of the signal and distortion from part of the balanced amplifier are combined with a reference signal such that the two signals destructively combine leaving the distortion from the sampled part of the balanced amplifier. The gain and phase of the distortion is then adjusted so that when it is coupled into the input of the other part of the balanced amplifier the distortion generated by both parts of the balanced amplifier are cancelled.

Abstract: A cancellation circuit is provided for canceling undesirable intermodulation (IM) products in electrical circuitry. The IM cancellation circuit includes a stepping spectrum analyzer which recognizes and measures the frequencies and amplitudes of different signal components of an RF signal across a desired frequency band. This information is forwarded to a processor which contains look-up tables or the like which provides information relating to the frequencies and/or amplitudes of signal components which are intended to reside in the RF signal. By comparison of the look-up tables to the frequencies and amplitudes measured and recognized by the sweeping spectrum analyzer, the processor of the cancellation circuit is able to determine whether the signal components in the RF signal are intended “information” carrying signals or unintended IM products.