Abstract: In order to provide a high frequency switch in which the setting range of the control voltage is expanded, the high frequency switch is constructed from a switch and a reference voltage generation circuit. The switch comprises first and second field effect transistors. In the first field effect transistor, the source electrode is connected to a signal input terminal, while the drain electrode is connected to a signal output terminal, and while the source electrode is connected to a control terminal. In the second field effect transistor, the source electrode is connected to the signal input terminal, while the drain electrode is connected to the signal output terminal, and while the gate electrode is connected to the control terminal.

Abstract: High efficiency DC to RF conversion with use of active harmonic insertion is provided for power amplification over a wide dynamic range of input signal level. Specifically, a power amplifier device including at least a final amplification stage is operated to receive an input signal of a fundamental frequency. A drive signal is produced which includes a fundamental signal component of the fundamental frequency and at least one harmonic signal component of a harmonic frequency that is substantially an integer multiple of the fundamental frequency, wherein relative phase shift and relative amplitude of the components are controlled over at least an order of magnitude of dynamic range of the input signal. As the signal level of the input signal decreases (or increases), the desired proportion of signal levels is maintained between the components.

Abstract: A method of producing an amplified signal decomposes a signal into at least a first part and second part using at least one amplitude threshold. The first part includes a portion of the signal with a lower peak-to-average power ratio than the signal based on the amplitude threshold. The second part includes a portion of the signal beyond the amplitude threshold. At least the first part and the second part are amplified to produce an amplified first part and amplified second part, which are combined to produce an amplified signal.

Abstract: Systems and methods for amplifying an RF input signal include employing a moderately power efficient wide bandwidth device, such as an AB-type amplifier, to amplify the power residing in the high frequency components of the input signal, and a highly power efficient narrow bandwidth device, such as a synchronous buck DC/DC converter, to amplify the power residing in the low frequency components of the input signal. The amplified low frequency components and high frequency components are then combined to produce an amplified replica of the RF input signal. A positive feedback loop is provided between the output of the AB-type amplifier and the input of the DC/DC converter to provide stability to the amplified RF signal. A negative feedback loop is provided between the output of the DC/DC converter and the input of the AB-type amplifier to minimize interference introduced by the DC/DC converter.

Abstract: The present invention relates to a linearisation method and signal processing device for reducing intermodulation distortions by extracting harmonic components generated from first and second carrier signals with different carrier frequencies, which are input into two first non-linear stages (11, 12). The harmonic components may be generated by the two first non-linear stages (11, 12) or by two additional harmonic generating elements (NE1, NE2). The extracted harmonic components are phase and/or amplitude adjusted and mixed with harmonic components generated in a second non-linear stage (4) to thereby reduce harmonic components so as to achieve a linear output waveform. Thus, an intermodulation distortion suppression can be achieved over the entire operating bandwidth, wherein no phase coherency of the two carrier signals is required.

Abstract: In an output stage of an electronic signal processing circuit such as that used for transmission from a mobile telephone set the amplifier circuit comprises two power transistors (A, B) or type FET. The power transistors are used for amplifying different signals such as signals for different wavelength bands in a duel band telephone set and they are not used simultaneously. Each power transistor comprises a multitude of elementary transistors (19, 21) or “fingers” which are interdigitated to form an interleaved configuration, the element transistors of one transistor alternating with the element transistors of the other transistor. Thereby the effective area which can receive heat dissipated by the element transistors will be twice that used when the element transistors are located in two geometrically separated groups which will allow a higher power load on each transistor element.

Abstract: A GaAs MMIC dual-band amplifier for wireless communications is disclosed for operation at either the 800 MHz or the 1900 MHz band and it provides desired gain and input and output impedance. Switching impedance networks are used at the input and output of the amplifier to provide matching input impedance and desired output impedance for operation in the two bands. Switching impedance networks are also used between any successive stages of the amplifier to provide proper interstage impedance. The dual band amplifier includes a bias control circuit which biases the amplifier to operate in A, B, AB or C mode. The amplifier can be used for the AMPS 800 or the GSM 900 operation or any other cellular operation such as the PCS 1900 and the it can be switched between the two operations by simply applying a proper control signal to the amplifier.

Abstract: A radio frequency (RF) coupler apparatus (312) suited for use in a multi-band wireless communication device (200), has a termination device (316) and couplers (314 and 315). Each of the couplers (314 and 315) has through-path coupling elements (318 and 320) and coupled-path coupling elements (319 and 321). Through-path coupling elements (318 and 320) pass a RF signal that is to be transmitted respective frequency bands (TX BAND 1, TX BAND 2) within which the device (200) operates. Coupled-path coupling elements (319 and 321) couple the RF signals passed by respective through-path coupling elements (318 and 320). The coupled-path coupling elements (319 and 321) and the termination device (316) are coupled in series, thereby permitting compatibilty with a RF power detector (313) that uses a single detection diode (322).

Abstract: The present invention aims to provide a RF amplifier capable of controlling the generation of spurious signals when plural carriers are simultaneously amplified. The RF amplifier includes dividers for respectively dividing each of a plurality of input signals different in frequency of carrier from one another into plural form, phase shifters for respectively assigning weights to phases every divided signals corresponding to a number obtained by subtracting 1 from the divided plural numbers, first combiners for adding up the signals different in the frequency of carrier, of the divided signals and the signals subjected to the phase weighting, amplifiers for respectively amplifying signals outputted from the first combiners, and a second combiner for adding the signals outputted from the amplifiers together to thereby output one signal from the second combiner. Spurious signal components are canceled out by addition of the output signals of the amplifiers.

Abstract: The invention provides a power sharing amplifier system having an N by N transform matrix circuit, N amplifiers and an N by N inverse transform matrix circuit. The N by N transform matrix circuit has N input ports that respond to M input signals and provide N transform matrix input signals, where M is less than N. The N by N transform matrix circuit features at least one input port that does not receive an input signal but instead is coupled to ground. The N amplifiers respond to the transform matrix input signals and provide N amplified transform matrix input signals. The N by N inverse transform matrix circuit responds to the N amplified transform matrix input signals and provides N inverse transform matrix amplified output signals to output ports. Moreover, the N by N inverse transform matrix circuit features at least one output dissipation port that is coupled to ground to dissipate the intermodulation products contain thereon.

Abstract: An amplifier circuit formed on a single semiconductor substrate includes a first amplifier having at least one stage for amplifying signals within a first frequency band; a first amplifier having at least one stage for amplifying signals within a second frequency band; and a tapped coil having one end thereof coupled to a stage of the first amplifier and a tap thereof coupled to a stage of the second amplifier. The amplifier circuit may be an RF amplifier circuit, a first portion of the tapped coil serving as an RF choke for said stage of the first amplifier, and a second portion of the tapped coil serving as an RF choke for said stage of the second amplifier. Sharing the tapped coil between multiple band amplifiers increases integration density.

Abstract: An amplifier (600) includes a first terminal (605) for receiving forward signals in a first frequency band and a second terminal (655) for receiving reverse signals in a second frequency band. A single gain block (630) is coupled between the first terminal (605) and the second terminal (655) for amplifying the forward signals and the reverse signals. The forward signals, after amplification, are provided to the second terminal (655) for transmission from the amplifier (600), and the reverse signals, after amplification, are provided to the first terminal (605) for transmission from the amplifier (600). In this manner, both forward and reverse signals, which are transmitted in separate frequency bands, can be amplified by a single gain block (630).

Abstract: To achieve an improved matching of a power amplifier to transmission line impedances of different transmission branches in a dual band mobile phone there is proposed a new power amplifier output circuit for such a dual band mobile phone. This power amplifier output circuit comprises a transmission branch change over unit being connected to an output terminal of the power amplifier. Further, there is provided a second impedance matching means in at least one transmission branch and the transmission branch change over unit comprises at least two switching elements between the first impedance matching unit and the second impedance matching unit. Therefore, the disturbing influence of parasitic elements in the switching elements may be reduced significantly.

Abstract: A method of producing an amplified signal decomposes a signal into at least a first part and second part using at least one amplitude threshold. The first part includes a portion of the signal with a lower peak-to-average power ratio than the signal based on the amplitude threshold. The second part includes a portion of the signal beyond the amplitude threshold. At least the first part and the second part are amplified to produce an amplified first part and amplified second part, which are combined to produce an amplified signal.

Abstract: Systems and methods for amplifying an RF input signal include employing a moderately power efficient wide bandwidth device, such as an AB-type amplifier, to amplify the power residing in the high frequency components of the input signal, and a highly power efficient narrow bandwidth device, such as a synchronous buck DC/DC converter, to amplify the power residing in the low frequency components of the input signal. The amplified low frequency components and high frequency components are then combined to produce an amplified replica of the RF input signal. A positive feedback loop is provided between the output of the AB-type amplifier and the input of the DC/DC converter to provide stability to the amplified RF signal. A negative feedback loop is provided between the output of the DC/DC converter and the input of the AB-type amplifier to minimize interference introduced by the DC/DC converter.

Abstract: A power amplifier circuit has a driver amplifier stage including a low band driver amplifier and a high band driver amplifier. A final amplifier stage includes a linear mode amplifier for amplifying digitally modulated signals and a saturated (nonlinear) mode amplifier for amplifying frequency modulated (analog) signals. A switching network interconnects the driver amplifier stage and the final amplifier stage. Depending on the desired mode of operation, an appropriate driver amplifier can be coupled to an appropriate final amplifier to most effectively and efficiently amplify analog or digital RF signals in either of a plurality of frequency bands. A diplex matching circuit is coupled to the linear mode final amplifier for impedance matching and for separating D-AMPS (800 MHz band) and PCS (1900 MHz band) digital signals. A power impedance matching circuit is coupled to the output of the saturated mode final amplifier.

Abstract: A signal amplification system involves decomposing a signal into two or more parts, amplifying the parts and then combining the amplified parts to produce the amplified signal. The decomposition can be done such that the resulting parts have characteristics that are amenable to efficient amplification. For example, decomposition of the signal to be amplified can be done using at least one threshold. The first part of the signal to be amplified can be formed by the portion of the signal within the threshold. As such, because the first part forms a signal with a lower PAR, the first part of the signal can be amplified more efficiently than the original signal. The second part of the signal can be formed by the portion of the original signal beyond the threshold. Because the second part is mostly zero, the second part can also be amplified efficiently, for example with a class C type amplifier which does not dissipate any energy when the input signal is zero.

Abstract: A high-frequency power amplifier for feeding an antenna of a nuclear magnetic resonance tomography apparatus has at least one amplifier stage that can emit a maximum output power within a first frequency band. Circuitry for frequency-dependently altering the maximum output power is connected to the amplifier stage, whereby the maximum output power within a second frequency band, that is higher than the first frequency band is higher than within the first frequency band.

Abstract: A GaAs MMIC dual-band amplifier for wireless communications is disclosed for operation at either the 800 MHz or the 1900 MHz band and it provides desired gain and input and output impedance. Switching impedance networks are used at the input and output of the amplifier to provide matching input impedance and desired output impedance for operation in the two bands. Switching impedance networks are also used between any successive stages of the amplifier to provide proper interstage impedance. The dual band amplifier includes a bias control circuit which biases the amplifier to operate in A, B, AB or C mode. The amplifier can be used for the AMPS 800 or the GSM 900 operation or any other cellular operation such as the PCS 1900 and the it can be switched between the two operations by simply applying a proper control signal to the amplifier.

Abstract: Disclosed is a high-efficiency amplifying device wherein a control signal for a power-amplifying unit is produced from an input signal in a pre-amplification stage, resulting in a reduced disturbance output signal with a constant efficiency in the amplifying device.

Abstract: A GaAs MMIC dual-band amplifier for wireless communications is disclosed for operation at either the 800 MHz or the 1900 MHz band and it provides desired gain and input and output impedance. Switching impedance networks are used at the input and output of the amplifier to provide matching input impedance and desired output impedance for operation in the two bands. Switching impedance networks are also used between any successive stages of the amplifier to provide proper interstage impedance. The dual band amplifier includes a bias control circuit which biases the amplifier to operate in A, B, AB or C mode. The amplifier can be used for the AMPS 800 or the GSM 900 operation or any other cellular operation such as the PCS 1900 and the it can be switched between the two operations by simply applying a proper control signal to the amplifier.

Abstract: A power amplifier includes a first amplifier, a second amplifier, a transfer switch and a controller. The first amplifier amplifies a first frequency bandwidth, and the second amplifies a second frequency bandwidth. The second frequency bandwidth is less than the first frequency bandwidth. The transfer switch includes a first input port, a second input port, a first output port and a second output port. The first input port is connected to a primary power source, while the second input port is connected to a battery. The first output port is connected to the first amplifier and the second output port is connected to the second amplifier. The controller controls the transfer switch to connect the first primary power source to the first amplifier in a primary mode of operation. The controller also controls the transfer switch to connect the battery to the second amplifier in a second mode of operation.

Abstract: A calibration method and apparatus for calibrating and linearizing an amplifier in which an input signal is decomposed into N channels. Then the amplifier is modeled to generate an estimated amplifier transfer function for each channel. Using the estimated amplifier transfer function for each channel, equalizer values are computed for equalizers that are applied to each channel prior to amplification, thus enabling the amplification of amplitude and/or phase modulated signals via the non-linear amplifiers.

Abstract: The present invention is a Comb linear amplifier combiner (CLAC) apparatus that allows one or more transmitters to transmit through one transmit antenna. The CLAC apparatus passes low powered transmit signals through a bank of bandpass filters. The transmit signals then pass through Class A amplifiers which amplify the transmit signals to the full transmit power. The full transmit power signals then pass through a second bank of bandpass filters. The transmission signals are then transmitted through a single transmission antenna.

Abstract: An amplifier circuit (20) uses a series transistor (38) to couple the output of an amplifier (26) to a tuned circuit load (40) and to act as a variable resistance. In one embodiment for a multi-band receiver, multiple series transistors (38, 42) are switched for connecting different tuned circuits (40, 44) to the amplifier's output, and an activated one of the series transistors receives a gate voltage that varies its resistance so as to achieve gain control. An activated series transistors can also provide a resistance that stabilizes the amplifier (26).

Abstract: A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), an adaptive split band modulator (270), and a power amplifier (260). The adaptive split band modulator (270) amplifies the low frequency components using a class S modulator (760), and amplifies the high frequency components using a class B amplifier (750). The power supply of the class B amplifier (750) is adaptively modified as a function of the amplitude of the signal that it amplifies. In this manner, the class B amplifier (750) operates at a higher efficiency.

Abstract: A wireless communication device, such as a dual-mode cellular phone, receives radio frequency (RF) signals in either of two communication bands. Each received RF signal is passed to two bandpass filters, one for each communication band, the outputs of which are connected to a single amplifier. The amplifier processes the received signal regardless of the communication band in which the signal was received. The amplifier can include two sets of similar circuitry, e.g., matching circuits, one for each communication band, which are selected alternatively to process received signals in the corresponding communication band.

Abstract: In a communications system, a multi-band power amplifier is employed to increase the power level of a signal for transmission over one of multiple frequency bands. In addition, a multi-band low noise amplifier is employed to scale the signal level of a signal received from one of the multiple frequency bands. In accordance with the invention, each multi-band amplifier is designed such that the gain values afforded by the amplifier to the components of the communication signal within the multiple frequency bands are significantly higher than the gain values to the signal components outside those bands.

Abstract: A power amplifier including: a first amplifier PA2 having an input terminal and an output terminal; a passive circuit PC3 having an input terminal and an output terminal; and a first switch SW2 having a single-pole terminal and two multi-throw terminals, one of the multi-throw terminals of the first switch SW2 being connected to the input terminal of the first amplifier PA2 and the other of the multi-throw terminals of the first switch SW2 being connected to the input terminal of the passive circuit PC3. This makes it possible to provide a power amplifier and a communication unit which can be operated with different frequencies, output powers or modulation types.

Abstract: A facility (VOR) is disclosed for combining and amplifying two broadband signals which are received from different transmission networks (NET1, NET2) and are transmitted in transmission channels separated in frequency. The facility (VOR) contains a broadband amplifier (BV), a preamplifier (VV), and a frequency filter unit (FW). The preamplifier (VV) and the frequency filter unit (FW) condition the signals to be amplified and establish an optimized signal-to-noise ratio between the two combined broadband signals: The preamplifier adapts the level of one of the signals to the level of the other signal, e.g., to the same value, whereby a linear and increased amplification is achieved in the broadband amplifier, and the filtering of the signals in the frequency filter unit prevents interfering signals, e.g., noise, contained in said one signal from getting into the frequency band occupied by the other signal and vice versa when the two signals are combined.

Abstract: An amplifier includes an amplifying section for simultaneously amplifying a plurality of input signals having different frequency bands, a distortion extracting section for separating and extracting at every different frequency bands a distortion component from a plurality of signals having the different frequency bands outputted from the amplifying section, a distortion compensation section for adjusting independently at every different frequency bands the phase and the amplitude of the distortion component separated and extracted at every different frequency bands and a distortion eliminating section for canceling and outputting a distortion component from a plurality of signals having the different frequency bands outputted from the amplifying section based on the distortion component adjusted at every different frequency bands.

Abstract: A very-wide-dynamic-range amplifier with very low-noise in the high-gain mode and very high-input-overload in the low-gain mode. The amplifier utilizes two parallel signal paths, one a high-gain, low-noise path and the other a low-gain, high-input-overload path. Each path includes a gain-control capability so that the gain of each path, and the contribution of the gain of each path to the overall gain of the amplifier may be smoothly varied from a very low-gain to a very high-gain. Specific embodiments including input impedance matching capabilities are disclosed.

Abstract: Amplifier-induced intermodulation distortion (IMD) is reduced by encoding a multi-frequency input composite signal into multiple encoded signals that vary from each other in their power amplitudes as a function of frequency, amplifying the encoded signals, and then decoding them in a complementary fashion so as to differentiate between the amplified signal components and the IMD components. The amplified signal components are coherently combined to separate them from the IMD components, which are incoherently combined. The input signal is preferably encoded by dividng it into multiple divided signals, introducing relative phase shifts between the divided signals that vary as a function of frequency, and combining the divided and phase shifted signals with each other in a Butler matrix prior to amplification. The phase shifts are introduced by means of time delays that are preferably equal to integer multiples of 4.PI. divided by the input signal bandwidth.

Abstract: A low-power op-amp circuit (70) having boosted bandwidth comprises a DC circuit block (72) which is coupled to first (V.sub.DC +, V.sub.DC +, V.sub.AC +) and second (V.sub.DC -, V.sub.AC) input nodes and to an output node (V.sub.OUT) of an output stage (90). The DC circuit block (72) amplifies a differential signal received from the first (V.sub.DC +, V.sub.AC +) and second (V.sub.DC -, V.sub.AC) input nodes, and provides an amplified signal to the output node (V.sub.OUT). An AC circuit block (74) is coupled to the output (NODE 3) of the DC circuit block (72). The AC circuit block (74) is operable to monitor a transient change between the first (V.sub.DC +, V.sub.AC +) and the second (V.sub.DC -, V.sub.AC -) input nodes. The AC circuit block (74) is further operable to transfer charge to the output node (V.sub.OUT) in response to the transient change, thereby providing boosted bandwidth beyond that of the DC circuit block (72) alone.

Abstract: Various circuit techniques to implement continuous-time filters with improved performance are disclosed. The present invention uses RMC type integrators that exhibit lower harmonic distortion. In one embodiment, a novel high-gain two-pole operational amplifier is used along with RMC architecture to achieve lower harmonic distortion. In another embodiment, the present invention uses dummy polysilicon resistors to accurately compensate for the distributed parasitics of the polysilicon resistors used in RMC integrator. In yet another embodiment, the present invention provides an on-chip tuner with a differential architecture for better noise immunity.

Abstract: A voltage isolation circuit having an improved method of combining the HF path and LF path is provided. The LF path comprises an opto-isolator to achieve voltage isolation of the input signal while passing low frequencies. The HF path comprises a transformer to achieve voltage isolation of the input signal while passing high frequencies. The HF path and LF path are combined at a summing node to obtain an isolated input signal. Obtaining a flat frequency response requires that the cross-over frequency between the LF path and HF path be closely matched. A portion of the LF path is injected into the HF path such that LF components are canceled out in the region of the transition frequency. In this way, the pole frequency of the transformer in the HF path may be compensated for to achieve a flat frequency response for the combined LF and HF paths.

Abstract: A musical instrument amplifier system (FIGS. 1 and 2) with a frequency selective crossover circuit (10) using passive band pass filters (36, 44) to separate the amplified signals from the power amplifier (14) of an amplifier system (12) into low frequency signals on an output connector (42) for a specially adapted bass audio speaker (38) while the higher frequency signals are applied to another speaker (46). The crossover circuit (10) is selectively connected with the normal speaker output (24) in lieu of the speaker (38) to add frequency crossover capability to any amplifier system. In another musical instrument amplifying system (88), the crossover circuit (FIG.

Abstract: A dual band filter network for a radio communication apparatus is provided. The network has an antenna (212) for receiving and transmitting signals from a first frequency band and a second frequency band. The network has a first duplex pair (202) including a first transmit filter (204) including a first passband and stopband. The first duplex pair (202) also includes a second receive filter (206). The first filter (204) presents a consistent phase in the second passband due to the wide frequency separation between the first filter (204) and the second filter (206). The network has a second duplex pair (202') with similar characteristics as the first duplex pair (202). The network also has a switching circuitry (210) controlled by a switch control voltage (214) for selecting the appropriate filter circuitry. The network can be provided in a small sized, low cost package that also offers improved insertion loss performance.

Abstract: An equaliser circuit arrangement for compensating for the frequency-dependent characteristics of a transmission line such as an untwisted pair, for lines of lengths up to, say, 125 meters and at data rates up to, say, 155MBits/sec., in which signals from the transmission line are applied by way of a unity gain path and a frequency-selective path including a first wide-band amplifier of variable gain to a summing node. The signals at the summing node may be further amplified by a second wide-band variable gain amplifier using gain control signals derived for the first amplifier.

Abstract: An audio amplifier (20) which includes an arrangement (300) for influencing an audio signal applied to the audio amplifier (20). This arrangement (300) has an amplifier for additionally amplifying a high-frequency range of the audio signal relative to the rest of the audio signal. This additional amplification takes place once a value of the audio signal has exceeded a limit value. The additional amplification only takes place for a brief period of time. The audio amplifier additionally amplifies high-frequency peaks in the audio signal for a brief period of time. The rising and falling slopes of these peaks are briefly enlarged as a result. Especially for pop music, this appears to be an attractive effect.

Abstract: A land mobile radio system (110) includes a plurality of radio channels (112), each radio channel (112) being interconnectable (115) to any one of a number, N, of combiners (114), and each combiner (114) being associated with a corresponding transmit antenna (120). A combiner output signal at the output of each combiner (114) is connected to a transform matrix (133) which divides each combiner output signal into a number, N, of transformed signals, each transformed signal containing an equal power level part, 1/N, of each combiner output signal. Each transformed signal is provided to an amplifier (135) for amplification thereof, and the amplified transformed signals are provided to an inverse-transform matrix (138) which recombines the equal parts of each amplified transformed signal into amplified combiner output signals which are provided to the antennas (120) for transmission thereof. The land mobile radio system (110) includes N antennas (120), and where N is a power of m, e.g., N=m.sup.

Abstract: A GaAs MMIC dual-band amplifier for wireless communications is disclosed for operation at either the 800 MHz or the 1900 MHz band and it provides desired gain and input and output impedance. Switching impedance networks are used at the input and output of the amplifier to provide matching input impedance and desired output impedance for operation in the two bands. Switching impedance networks are also used between any successive stages of the amplifier to provide proper interstage impedance. The dual band amplifier includes a bias control circuit which biases the amplifier to operate in A, B, AB or C mode. The amplifier can be used for the AMPS 800 or the GSM 900 operation or any other cellular operation such as the PCS 1900 and the it can be switched between the two operations by simply applying a proper control signal to the amplifier.

Abstract: Disclosed is a channelized multi-carrier signal processor capable of equalizing power levels of individual carriers of a multi-carrier signal to within a predetermined dynamic range. In one embodiment, the signal processor includes a power splitter for splitting a multi-carrier input signal into a plurality of electrical paths. In each electrical path there resides a signal modifier that is operable to isolate signal energy associated with a given carrier of the multi-carrier signal. Each signal modifier includes an automatic gain control (AGC) circuit to control the power level of the carrier isolated therein to within a predetermined power level window so that the isolated carriers of each signal modifier are equalized in power. A power combiner then combines the equalized carriers to produce a multi-carrier output signal, which can be applied to a limited dynamic range device such as an A/D converter.

Abstract: A state-variable pre-amplifier responsive to a program input signal drives a filter circuit, and an absolute value circuit. The state-variable pre-amplifier uses a state-variable filter to provide a compensated signal at an output. The compensated signal has compensated high, low and mid-range frequency signal components. The pre-amplifier has a first amplifier stage for providing a high frequency compensated signal. A second amplifier stage provides a mid-range frequency compensated signal. A third amplifier stage provides a low range frequency compensated signal. An adjusting means adjusts the balance between at least two of the three frequency compensated signals. A summing circuit adds the three compensated signals to form the compensated signal. A balance means adjusts the balance between the high frequency, the mid-range and the low frequency compensated signals to provide a compensated signal.

Abstract: A signal conditioning system that receives inputs from at least one pair of conductors connected to its input. Each such input is processed by an input filter and presented to a buffer amplifier. Each such input filter and buffer amplifier refers to and is powered by independent power sources whose power return reference potentials are independently determined by the potential of the corresponding input signal potential reference conductor for the signal frequencies of interest. The outputs of all such buffer amplifiers, the power return reference potentials, and the power return reference potential of the conditioning circuit output are all appropriately added or subtracted in the next circuit stage. This circuit stage consists of an amplifier buffer having low output impedance which is powered by another independent power source whose power return reference potential is independently determined by the potential of the output signal reference conductor.

Abstract: A split-path isolation amplifier (10) employs a transformer (30) in a high path (26) and a single-input, dual-output closed-loop optocoupler (66) in a low path (24) to achieve a flat, wide frequency response without need for frequency compensation adjustments. In a low path frequency region (106), the optocoupler provides all or most of the signal to the output. The isolation amplifier employs a substantially overlapped crossover frequency region (104) in which the high path signal is applied to a primary winding (28) of the transformer, and the low path signal is applied differentially to secondary windings (40, 42) of the transformer. At frequencies below the crossover frequency range, the signal from the optocoupler dominates as the signal coupled from the primary winding rolls off. At frequencies above the crossover frequency range, the signal coupled from the primary winding dominates as the signal from the optocoupler rolls off.

Abstract: An amplifier circuit having a pre-amplifier responsive to a program input signal, a filter circuit, and an absolute value circuit. The pre-amplifier provides automated balancing between the high frequency channel signals and the mid range channel signals to provide a compensated signal. The filter circuit is coupled to receive and automatically filter the compensated signal to provide an output signal and a modified compensated signal. The filter circuit has an adjustable bandwidth that is automatically adjusted in response to the control signal for automatically reducing the bandwidth of the filter circuit in response to lower values of the control signal to obtain the output signal. The filter circuit uses a voltage controlled amplifier or a photo cell in combination with an integrator. An absolute value circuit senses the modified compensated signal and provides a control signal proportional to the average peak value of the amplitude of the modified compensated signal.

Abstract: An optical receiver receives a wideband input signal and separates the wideband input signal into at least a first narrowband signal (FB.sub.1) and a second broadband signal (FB.sub.2). A photodiode (3) receives the wideband input signal and generates a photo-current responsive to the wideband input signal. The photodiode has a first terminal (K) and a second terminal (A). First (1) and second (2) subcircuits respectively are coupled to receive the photo-current generated by the photodiode (3). The first subcircuit (1) includes an amplifier. The first narrowband signal (FB.sub.1) and the second broadband signal (FB.sub.2) are respectively separated from the wideband input signal with the first subcircuit (1) and the second subcircuit (2). The narrowband signal (FB.sub.1) includes a digital (telephone) signal and the broadband signal (FB.sub.2) includes a CATV signal which are both included in the wideband input signal.

Abstract: An input circuit for an apparatus for measuring an electric signal having a measuring section to measure an electric signal. An input signal path for outputting an input signal to be measured from an input terminal to the output side has a composite buffer amplifier connected to the output side.

Abstract: A signal conditioning system that receives inputs from at least one pair of conductors connected to its input. Each such input is processed by an input filter and presented to a buffer amplifier. Each such input filter and buffer amplifier refers to and is powered by independent power sources whose power return reference potentials are independently determined by the potential of the corresponding input signal potential reference conductor for the signal frequencies of interest. The outputs of all such buffer amplifiers, the power return reference potentials, and the power return reference potential of the conditioning circuit output are all appropriately added or subtracted in the next circuit stage. This circuit stage consists of an amplifier buffer having low output impedance which is powered by another independent power source whose power return reference potential is independently determined by the potential of the output signal reference conductor.