Abstract: A circuit arrangement in which an RF amplifier circuit also acts as a filter for a second supply voltage which is produced from the supply voltage (V.sub.cc out) of the amplifier. The high frequency RF amplifier circuit comprises a common emitter transistor with ancillary components, and the emitter is connected through a capacitor to the ground of the circuit. From the emitter of the transistor is obtained the second supply voltage (V.sub.cc out) in which the filter circuit is said high frequency amplifier circuit wherein the transistor is used as an emitter follower. With the circuit arrangement of the invention, the separate high frequency amplifier circuit and the filtering circuit of the second supply voltage, both known of prior art, can be combined.

Abstract: A high power field effect transistor (FET) amplifier which can provide a high gain over a wide bandwidth of a microwave range includes, on a first substrate on which a grounded-source field effect transistor is disposed, a series combination of an inductor and a capacitor connected between the gate of the FET and ground. The gate of the FET is coupled to an input impedance matching circuit disposed on a second substrate. The drain of the FET is coupled to an output impedance matching circuit disposed on a third substrate.

Abstract: A selection unit, which is provided between an input matching unit and a high frequency amplification unit, is used to select a specific high frequency band to be amplified by the high frequency amplification unit from high frequency signals input from an input terminal. Further, an attenuation unit, which is provided between an input of the high frequency amplification unit and ground, is used to attenuate the input high frequency signals except for the specific high frequency band. Therefore, the specific high frequency band of the input high frequency signals is transferred from the input terminal to the high frequency amplification unit through the selection unit with a small loss, and the input high frequency signals except for the specific high frequency band are attenuated by the attenuation unit.

Abstract: A filter with adjustable edge steepness includes input terminals for applying a signal to be filtered. One of the input terminals is connected to a reference potential. A signal-forming device is connected to the input terminals for forming a first signal and a second signal from the signal to be filtered. The signal-forming device adjusts a difference between the first signal and the second signal. A subtraction device is connected to the signal-forming device for forming a differential signal from the first signal and the second signal. A frequency-dependent device has an input terminal connected to the subtraction device, an output terminal for supplying another signal, and a filter transfer characteristic to be delivered to the differential signal. An addition device has an output and is connected to the signal-forming device and to the output terminal of the frequency-dependent device for forming a summation signal at the output from the first signal and the other signal.

Abstract: An amplifier is compensated for variations in element values. A trim signal is generated based on element values of filter elements of a filter in the amplifier. An RC product in the amplifier is controlled based on the trim signal. The RC product corresponds to a product of a dynamic resistance value of a dynamic resistance element in the filter in the amplifier, and a capacitance value of capacitive elements in the filter. The RC product also determines a pole position of the amplifier. Gain in the amplifier is controlled based on the trim signal so that a desired gain is maintained.

Abstract: A wideband tunable (programmable) filter includes first-order and second-order filter circuits employing bipolar transistors. The bandwidth of the filter circuits are set by the product of the dynamic emitter resistance of the transistors and directly coupled on-chip capacitances. The filter bandwidth is inversely proportional to the time constant. To adjust the resonant frequency of the filter networks, emitter currents are varied, which in turn controls the emitter resistances. As the resonant frequency of the filter network is varied, the gain and normalized frequency response of the various output nodes remain constant. In the second-order configuration, the damping ratio of the filter is set using "positive" feedback, for a Q of greater than one-half, with a loop gain of less than one. Temperature compensation is accomplished by use of a temperature "dependent" voltage network.

Abstract: A differential amplifier comprises a pair of current mirror circuits, a pair of constant current supplies and a pair of differential amplifier circuits. The first differential amplifier circuit is provided between the first current mirror circuit and the first constant current supply. The second differential amplifier circuit is positioned between the second constant current supply and the second current mirror circuit. The second differential amplifier circuit includes a pair of multicollector pnp transistors each having a first one of its collectors connected to the second current mirror circuit and a second one of its collectors connected to the second power supply.

Abstract: The invention relates to a circuitry arrangement by means of which it is possible to suppress frequency components which cause spurious response in the intermediate frequency amplifier in a radio telephone receiver. The amplifier produces not only the input signal frequency but also harmonic frequencies of this frequency, in which case some harmonic frequency of the frequency component which causes spurious response is the same as the intermediate frequency. In the circuitry, between the signal path and the circuit ground, there is a circuit which is in series resonance at the frequency of the frequency component which causes spurious response, in which case a signal of this frequency is strongly attenuated, and the circuit is in parallel resonance at the intermediate frequency, in which case attenuation of a signal of this frequency is slight.

Abstract: A differential amplifier includes a bias current source and a current dividing circuit for controllably dividing a bias current between first and second current paths. A first pair of matched transistors is connected as a differential pair between matched load impedances and the first current path. A second pair of matched transistors is connected as a differential pair between the matched load impedances and the second current path. Differential inputs of the second differential pair are connected to corresponding differential inputs of the second differential pair. The transistors of the first and second pairs have different emitter areas. Matched capacitors may be connected between respective differential inputs and differential outputs of the differential amplifier. The load impedances may be tapped to provide outputs having a lower differential gain. The differential amplifier is useful for building resonant circuits, for example voltage controlled oscillators having high Q factors.

Abstract: The present invention is a new design for transconductance elements useful in high-frequency filters such as fully differential state-variable biquads. The present invention enjoys a large dynamic range. It is built with simple circuitry to reduce parasitic capacitance which impedes high-frequency operation. It is easily tunable for use in programmable filters. It is configured in a fully differential circuit and operates on five volts. The present invention is also very useful for implementing dual-input or multiple input transconductance elements. By incorporating additional current sources in the present invention, another degree of freedom is added to the determination of pole frequency and pole quality factors, when the transconductance is used as a biquad filter building block.

Abstract: An amplifier is comprised of a GaAsFET transistor connected between input matching circuit and output matching circuit for effecting amplification in microwave band and milliwave band. A filter circuit is interposed between the input matching circuit and a gate electrode of the transistor so as to selectively reduce an input impedance at 1/2 frequency of the operation frequency to thereby stabilize the operation of the transistor.

Abstract: Linear high gain (greater than 20 dB) and high power (greater than +20 dbm) devices for RF power amplifiers are achieved using either fully monolithic or hybridized versions of silicon MMIC two-stage cascaded amplifiers. The device features three feedback loops in conjunction with a DC biasing network. Resistor-capacitor feedback circuits utilize only two capacitive elements which are provided as a single three-terminal element having a common lower plate.

Abstract: A band limiter connected between output lines of a differential amplifier. The band limiter includes a bipolar transistor connected to the output lines via capacitors, and includes a temperature detecting device for detecting ambient temperature. Transistor capacitance is connected to or disconnected from the output lines in response to a bandwidth limiting signal. The transistor constitutes a low-pass filter functioning as a band limiter when it is closed, whereas it functions as a variable capacitor which varies its capacitance in accordance with the ambient temperature when it is opened. The high-band frequency characteristic of the differential amplifier is temperature compensated by the transistor functioning as a variable capacitance.

Abstract: An input stage for a low-noise broadband amplifier includes a negative feedback capacitor connected between an input and an output of at least one amplifier element. The output of the amplifier element is terminated with a capacitor. The input stage has a real, constant input impedance in a broad range.

Abstract: An impedance matched class-F high frequency amplifier includes an input matching circuit receiving high frequency signals connected to the gate of the FET. The drain of the FET is connected to an output matching circuit which matches the fundamental frequency and the second harmonic frequency, and the output of the output matching circuit is connected to an even harmonic terminating circuit. The stray reactance componance at the output impedance of the FET is offset by the output matching circuit, and therefore the even harmonics terminating circuit can more accurately terminate the second harmonic frequencies.

Abstract: A leapfrog filter comprises a first integrator made up of a first operational amplifier and a first capacitor connected to output terminal of the first operational amplifier; a second integrator made up of a second operational amplifier and a second capacitor connected to inverting input terminal and output terminal of the second operational amplifier; and a variable current source circuit. The first operational amplifier has the output terminal thereof connected to non-inverting input terminal of the second operational amplifier. The second operational amplifier has the output terminal thereof connected to inverting input terminal of the first operational amplifier. An input terminal is connected to non-inverting input terminal of the first operational amplifier; and output terminal connected to the output terminal of the second operational amplifier.

Abstract: The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Abstract: A system is provided for use with an electrical musical instrument for conditioning electrical signals generated by the instrument and for creating controlled distortion. The system includes an amplifier circuit having an input for responding to the signals and an output to provide a conditioned output signal. There is included at least one bandpass filter for frequency preemphasis of the input signal. A limiting circuit is operatively connected to the bandpass filters limiting the amplitude of signals received from the bandpass filters to produce a relatively high distorted, long sustained signal. A notch filter operatively connected to the limiting circuit reduces the heavy mid-range frequency content produced by the combination of the bandpass filters and the limiting circuit. A low pass filter operatively connected to the notch filter further conditions the signal generating a conditioned output signal.

Abstract: An input signal is supplied to the non-inverting input terminal of a current differential amplifier. A capacitor is connected between the output terminal of the current differential amplifier and a power source and the capacitor stores charges according to an output signal of the current differential amplifier. The input signal and an output signal of the current differential amplifier are supplied to resistors via buffer circuits and signals divided by the resistors are added together by a buffer circuit and output from an output terminal and at the same time fed back to the inverting input terminal of the current differential amplifier.

Abstract: A balanced filter circuit includes only one balanced amplifier (10) having an inverting input (6) and a non-inverting input (5) and an inverting output (7) and a non-inverting output (8) for realization of filter transfer functions Uout/Uin of the second or higher order from an input signal Uin at input terminals (1, 2) to an output signal Uout at output terminals (3, 4) having passive admittances which are composed of a parallel-combination of a resistor (R42, R44) and/or a capacitor (C41, C44) and/or a number of series-combinations of a resistor (R41, R43, R45) and a capacitor (C42, C43, C45).

Abstract: An amplifier having band pass filters and resonators for injecting, mixing and downconverting, i.e., recycling, second and third harmonics to increase the amplifier's efficiency. Various aspects of amplifier design are developed for enhancing efficiency.

Abstract: An amplification circuit having a compensation circuit for receiving a control signal and generating a corresponding compensation signal according to predetermined compensation characteristics. An input amplification circuit is provided for, receiving an input signal and the compensation signal amplifying the input signal at an input gain level determined by the compensation signal and providing a corresponding input amplification circuit output signal. A filter element receives and filters unwanted frequency components from the input amplification circuit output signal. An output amplification circuit is provided for, receiving the filtered input amplification circuit output signal and the compensation signal, amplifying the filtered input amplification circuit output signal at an output gain level determined by the compensation signal and providing a corresponding output amplification circuit output signal.

Abstract: An amplifier circuit includes a high-gain amplifier, and a feedback circuit for extracting an unstable output having a level equal to or less than a threshold level from an amplified signal from the amplifier and for feeding back the unstable signal to the amplifier, so that the amplifier oscillates at a predetermined oscillation frequency. The amplifier circuit also includes a band rejection filter for passing signal components of the amplified signal other than an oscillation output which is obtained at the output terminal of the amplifier when the amplifier oscillates at the predetermined oscillation frequency. The signal components obtained from the band rejection filter are an output signal of the amplifier circuit.

Abstract: A monolithically realizable harmonic trapping circuit that is a shunt connected series-resonant inductor-capacitor combination which has a resonant frequency designed to coincide with an undesired harmonic frequency of a desired fundamental frequency signal.

Abstract: A field effect transistor amplifer has a high gain in a plurality of microwave frequency bands. In a field effect transistor with the gate terminal and the drain terminal thereof connected to a matching circuit on the input side and a matching circuit on the output side, respectively, a resonance circuit which is composed of a series circuit including at least one second inductor and a capacitor and connected in parallel to a resistor, is connected between at least one of the gate terminal of the field effect transistor and the ground and between the drain terminal of the field effect transistor and the ground. When a series circuit including the first inductor, at least one second inductor and the capacitor is resonated and short-circuited, the gain at the resonance frequency is dropped and a gain in the range outside of the desired bands is suppressed.

Abstract: The parasitic capacitance which is inherent in an amplifier stage fabricated by MMIC or MIC technology oftentimes is cumbersome and of little use. The present invention utilizes this parasitic capacitance for effecting a quadrature circuit, fabricated onto the same substrate as the amplifiers for matching and biasing the amplifiers, thereby providing for broadband operation. When a pair of amplifiers are driven in quadrature, there results a low Q, low inductance circuit which has enhanced efficiency and operates at a decreased temperature.

Abstract: A balanced filter circuit has a number of balanced pushpull amplifiers (10) whose inputs (11, 12) and outputs (13, 14) are coupled to filter resistors (20, 21, 22, 25, 27A/B) and filter capacitors (23, 24, 26A/B). In order to adjust the filter, the currents from the filter resistors to the inputs of the balanced amplifiers are varied by means of adjustable balanced multipliers (40).

Abstract: A first high inductor is connected between a ground point and the base of a high frequency amplifying transistor whose emitter is grounded. A first capacitor is connected between a mid-point of the first inductor and the ground point. A second inductor is connected between the collector of the transistor and a power source terminal. A second capacitor is connected between a mid-point of the second inductor and the ground point. The first inductor connects the base of the transistor to ground in a DC mode, and cooperates with the first capacitor to form a first series resonant circuit. The resonance frequency of the circuit is equal to half of the frequency "f" of an input signal to the transistor. The resonant first series circuit allows a signal of the f/2 frequency generated on the base side of the transistor to flow to the ground point. The second inductor feeds electric power to the collector of the transistor, and cooperates with the second capacitor to form a second series resonant circuit.

Abstract: In an ALC circuit for automatically performing an amplitude compression control operation according to the output level of a low frequency amplifier circuit, the output level of the amplifier circuit is subjected to amplitude compression according to the level of a control signal which is outputted in correspondence to the output level of the amplifier circuit. The differentiation time constant of a differentiating circuit (or cutoff frequency of a high pass filter) provided on the output side of the amplifier circuit is controlled according to the level of the control signal to control the cutoff frequency for the frequency band subjected to amplitude compression.

Abstract: A leapfrog filter comprising a first and a second integrator each consisting of an operational amplifier and integrating capacitor. The leapfrog filter includes differential amplifier which is arranged to differentially supply current to the first and second integrators through a first and a second current source circuit respectively; and a third current source circuit for adjusting the sum of currents supplied to the first and second current source circuits, wherein characteristics such as the center frequency f.sub.o and quality factor Q of the leapfrog filter are controlled by adjusting the respective current values.

Abstract: A charge amplifier circuit comprising an operational amplifier unit whose signal output is back to a signal input of the amplifier unit via a capacitative feedback element, the signal output of the operational amplifier unit also being coupled to an input of a following, further transmission unit that has a proportional, integrating transfer characteristic with a break-over frequency that is at least approximately equal to the break-over frequency of the operational amplifier unit, this being at least in the proximity of the break-over frequency defined by the feedback element of the operational amplifier unit. The feedback element of the operational amplifier unit can be optimized independently of the operating frequency range, this, allowing for a low resistance value for the feedback element given a transfer behavior that remains linear, this despite the low capacitor value that increases the charge sensitivity.

Abstract: A system is provided for use with an electrical musical instrument for conditioning electrical signals generated by the instrument. The system includes an amplifier circuit having an input for responding to the signals and an output to provide a conditioned output signal. At least one compressor is operatively connected to the input for responding to the amplitude of the signals to provide a compressed signal to the amplifier circuit that is variable as a nonlinear function of the amplitude. Also provided are a pair of bandpass filters in parallel for frequency preemphasis of the compressed signal. Also provided is time modulation circuitry for permitted certain musical sound effects.

Abstract: A general biquadratic filter circuit is described which uses operational transconductance amplifiers. A bias current controls the transconductance (gm) of the amplifiers which in turn control the corner frequency (Wo) of the circuit. The circuit is configured with three potential sources which can be preselected to either be at a ground level or at a desired voltage level. By preselecting which of the potentials are grounded and which are at a desired voltage level, the circuit can become either a lowpass, highpass, bandpass or notch filter.

Abstract: A two-stage, interstage transformer-coupled amplifier is provided with a degeneration resistor coupled between the collector of the first stage transistor and the power supply to limit the power dissipated in the first stage transistor. The first and second stages are coupled to ground through capacitor/inductor circuits to eliminate signal noise in the supply voltage. The output is filtered to remove harmonics and provide output impedance matching.

Abstract: A high frequency, negative feedback amplifier is coupled at its input to an inductance network which together with the input capacitance of the negative feedback amplifier forms a resonance circuit. The resonance frequency of the resonance circuit is set within the desired reception band of the amplifier, to thereby form a band pass filter having a pass band corresponding to the desired reception band. The resonance circuit assures only a real input to the amplifier thereby reducing the input noise attributable to the input source.

Abstract: The invention relates to an active RC filter arrangement comprising a balanced amplifier (A.sub.1) which can be extended to obtain an n.sup.th -order filter arrangement. Once a general n.sup.th -order filter arrangement has been created it can be modified to obtain, inter alia, a low-pass, a high-pass or an all-pass n.sup.th -order active RC filter by merely changing the values of the resistors and capacitors.

Abstract: A hearing aid that is compact and efficient and that provides a high degree of control over its frequency response and also over its output level versus input level characteristic. The frequency response control includes an adjustable four pole high pass filter and an adjustable four pole low pass filter, to define the pass band, and an adjustable slope filter, to define the slope within the pass band. The control over the output level versus input level characteristic includes an input AGC system with well defined, independent control of compression threshold and compression ratio, an adjustable peak clipper, and a selectable output AGC system that tracks the peak clipper setting.

Abstract: An active filter circuit operable in a band-rejection mode and in an all-pass mode. A cascade combination of an RC filter and amplifier circuit receives an input signal. A pair of amplifiers respectively receive the input signal and the output of the RC filter and amplifier combination. The outputs of the amplifier pair are summed, and the circuit mode is determined by the RC component values and the amplifier gains.

Abstract: The invention can be related to the technical field of implementation and control of electricity controllable active fibers.In accordance with the invention filters are controlled and implemented with the aid of a differential gain stage. Said stage includes pairs of like amplification components (Q.sub.I11 and Q.sub.I21, Q.sub.I12 and Q.sub.I22, Q.sub.I13 and Q.sub.I23), and groups of series-connected diode components as well as at least one current generator (Q1, Q2, Q3). The forward voltage drop of the diode components has the same current responsiveness as the base-emitter voltage of the amplification components. A filter of the first order includes a differential gain stage with a capacitive component (C) connected across the output of said stage or to its amplification components. A filter of the second order can include two differential gain stages, each with its capacitive component (C1, C2) in circuit.

Abstract: A cascaded low pass/high pass filter phase shifter system including: a series of semiconductor switches each having a control electrode and first and second load electrodes; a capacitance connected in series between each control electrode and ground; an inductance connected in series between each second load electrode of one semiconductor switch and the first load electrode of the adjacent semiconductor switch in the series; and means for selectively applying a control signal to each said control electrode for switching the associated semiconductor switch between a first state in which it operates as a low pass filter and a second state in which it operates as a high pass filter to introduce a phase shift in a propagated signal.

Abstract: A variable bandwidth filter comprises a transistor long-tailed pair. One of the transistors of the pair has a field effect transistor which is connected in the collector circuit of the transistor and which is used as a variable collector load resistor. The field effect transistor is shunted by a capacitor and the gate of the field effect transistor is fed with a control voltage via a feed-back control loop arrangement which serves to maintain constant the d.c. voltage across the field effect transistor whereby the effective bandwidth of a filter circuit defined between the base of the said one transistor is arranged to be controllable in dependence upon the current in the common tail of the pair as determined by a variable current source connected in the tail.

Abstract: A variable gain transconductance amplifier wherein complimentary input followers are used in conjunction with the multiplier to provide a high input impedance. A pair of multiplier input devices are embedded in the input followers to reduce the supply voltage used by the multiplier and to improve signal handling capability while reducing the supply voltage required. Further, these variable gain transconductance amplifiers are used in active filters to provide adjustment of the bandwidth without affecting the center frequency.

Abstract: A preamplifier system adapted for a Loran receiver includes a buffer amplifier receiving the signal from the antenna at its input and a tuned circuit connected between the input of the buffer amplifier and ground. The tuned circuit includes a parallel combination of a resistance, capacitance and inductance with values selected such that a resonant frequency is provided substantially at or near the carrier frequency of the Loran signal to pass it while higher and lower frequencies, constituting extraneous noise signals, are substantially attenuated. In particular, low frequency, e.g. 60 Hz signals and DC from sources such as precipitation static, are shunted to ground through the parallel inductor in the tuned circuit so that these low frequency components do not affect the performance of the receiver.

Abstract: A variable equalization system is disclosed, in which a plurality of amplification cells having a plurality of filter groups with natural frequencies progressively increased four times are connected in series or in parallel, thereby making possible a variable equalization over a wide range of cable length.

Abstract: A double integration type filter circuit, consisting of a pair of integrators connected in series with each other, has a changeover switch for commutating the filter characteristics to a filter configuration which emphasizes portions proper to the characteristics of the filter circuit to facilitate filter adjustment to reduce filter adjustment time and to realize improved accuracy while providing for automatic adjustment of the filter characteristics.

Abstract: The invention relates to a circuit comprising an amplifier with bipolar transistors, which amplifier is fed by a signal source with a complex internal resistance and which has a signal negative feedback path connecting the amplifier output to the signal source. For reducing the noise, especially the input noise current which is particularly predominant in circuits of this kind which have a sufficiently large source impedance, a reactance network is arranged between the amplifier and the signal source. The network, in connection with the signal source and the negative feedback path, constitutes a filter which is parallel to the amplifier input and which has at least a series resonance frequency within the signal frequency range.

Abstract: In an amplifier comprising an amplifier transistor and a tunable selection circuit with a coil, a further coil is arranged between the collector of the amplifier transistor and the supply voltage source and is inductively coupled with the coil of the tunable selection circuit.

Abstract: A current mode active filter includes a differential amplifier, having two transistors, and a current mirror, having two transistors, connected into a feedback loop. The phase shift of the loop is controlled by one or two grounded capacitors and bias current sources connected to forward bias the base-emitter junctions of the transistors. The frequency of the filter is controlled by varying the dynamic resistances of the base-emitter junctions with the bias current sources. The current mirror increases loop gain, thereby enhancing the Q of the circuit. Improved dynamic range and large-signal performance can be achieved by the addition of two transistors to the current mirror circuit.

Abstract: An isolator for connection between an informational signal source and a high voltage controlled load may be used with numerous combinations of different input signal type and magnitude and output signal requirements. The compensation for input and output signal variation is accomplished by changing a minimum number of easily accessible plug-in passive circuit components.

Abstract: A VLF-VHF broadband in-line amplifier forms a portion of a towable buoyant able antenna system that is deployed in seawater from submarines. The amplifier is located between an antenna system and a coaxial cable. The coaxial cable is connected to the submarine. The VLF-VHF broadband in-line amplifier provides substantially uniform amplification for the frequency range of 10 kHz-160 MHz on signals received from the antenna system. The amplified signals are then transmitted to the submarine over the coaxial cable.