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: A phase stable limiting power amplifier includes a transistor, having a bias voltage applied to the collector and one applied to the base for operation in a class AB configuration. Input impedance matching circuitry may be coupled to the base with output impedance matching circuitry coupled to the collector. The input and output impedance matching circuitry may include only reactive elements for maximizing amplifier gain. Instability suppression circuitry may be connected between the base and the emitter. Representative functional characteristics for facilitating component selection and selection of operation conditions are provided.

Abstract: A wide bandwidth transconductance amplifier utilizing internal feedback is stabilized over a wide range of output currents. A compensation driver circuit senses the output current in the amplifier and feeds it back through a compensation capacitor. This keeps the bandwidth of the amplifier constant and optimally stabilized over a 16 to 1 range in output current. This compensation scheme eliminates compensation compromises that can limit the useful dynamic range of transconductnce amplifiers while offering a wide bandwidth low distortion transconductance with high output impedance over frequency.

Abstract: An analog active filter for realizing the secondary transfer function by using an amplifier having a feedback loop having a first integrating function block which integrates an input signal, second and third integrating function blocks which integrate an output signal, a first signal combining function block which combines signals from the first and second integrating function blocks with the input signal, a fourth integrating function block which integrates signals from the first signal combining function block, and a second signal combining function block which combines signals from the third and fourth integrating function blocks with the input signal and derives the output signal.

Abstract: The disclosure concerns a microwave amplifier. To improve the efficiency of an amplifier having a field-effect transistor, an input quadripole and an output quadripole, the voltage applied to the gate is limited to a deviation between the pinch-off voltage V.sub.P and the positive maximum gate voltage V.sub.GS, using a diode of a second order harmonic reverse feedback circuit. Application to microwave circuits.

Abstract: An integratable filter has a bandplass behavior and comprises a power source which is controllable with negative feedback by way of a resistor and a capacitor and whose output is charged with a further capacitor.

Abstract: A differential amplifier of the cascode type includes a differential stage having a first (T.sub.1) and a second (T.sub.2) transistor, whose emitters are connected to a first (I.sub.1) and a second (I.sub.2) current source, respectively, and are connected to each other through a first resistor (R.sub.12). The collectors of the first and second transistors are connected to an active load constituted by the collector-emitter path of a third (T.sub.3) and a fourth (T.sub.4) transistor, respectively, in series with a second (R.sub.3) and a third (R.sub.4) resistor, respectively, of which one terminal is connected to a supply voltage source. The third and fourth transistors have their bases connected to a reference voltage source. The base of the first and second transistor are connected through a first (C.sub.1) and a second C'.sub.1) capacitor to a current generator equivalent to a voltage source in parallel with an impedance.

Abstract: A feedback circuit couples a base amplifier output to the amplifier input for feeding back a portion of an amplified input signal. The feedback circuit includes an inductor coupled in series with a variable resistance. The variable feedback resistance is provided by a feedback FET having a gate for receiving a control signal for varying the resistance between the source and drain. The gain of the base amplifier is determined over the predetermined frequency range by the combined impedance of the inductor and resistance. The base amplifier is a field-effect transistor (FET). The feedback inductance is taken from a portion of a coil coupling the drain of the base FET with an output terminal.

Abstract: A single-ended input to differential output amplifier performs a predetermined transfer function on an input signal substantially independently of nonlinearities in component values. The input signal and a first reference voltage are coupled to a circuit network, which is coupled to a fully differential operational amplifier, to implement the predetermined transfer function. A common mode voltage between positive and negative output signals of the operational amplifier is sensed and fed back to the operational amplifier so that the operational amplifier may set the common mode voltage to a second reference voltage. The circuit network has first, second, and third capacitors, the third capacitor coupled between a positive input terminal and the first reference voltage.

Abstract: A high precision composite amplifier for use in a data acquisition subsystem of a Computerized Tomography (CT) scanner provides enhanced high speed response in terms of reduced settling time. The speed improvement is due to a novel compensation network in which a high frequency pole and a zero in the open loop response characteristic for the composite amplifier are forced to cancel despite component and temperature variations. The resulting amplifier exhibits a simple, higher speed, single pole response. An adjustable circuit is provided for adjusting the placement of the zero to assure optimum pole/zero cancellation.

Abstract: A broadband amplifier comprises a bipolar transistor (T), having a base connected to the input terminal (2), a collector connected to the output terminal (3) which is in turn connected to a supply source (11) through a first resistor (R1), and an emitter grounded. A second resistor (R2), the value of which varies simultaneously with the current gain (.beta.) of the transistor is connected between the output terminal and the transistor base. This broadband amplifier further comprises a capacitor (C) connected in parallel across the terminals of the second resistor and a third resistor (R3) connected between the second resistor and the transistor base.

Abstract: An amplifier circuit of this invention includes a first-stage amplifier, an amplifier element connected to the output terminal of the first-stage amplifier as a feedback load, and a further amplifier element connected between the output and input terminals of the amplifier element, and performs negative feedback through a load of the first-stage amplifier. As the amplifier element, a transistor is used, and as the further amplifier element, an emitter-follower transistor is used.

Abstract: A three-terminal operational amplifier includes a current input, in addition to the conventional inverting and non-inverting inputs. The current input is inverted and added to the inverting input current, while its voltage is urged to a level equal to that of the inverting and non-inverting inputs. The new amplifier employs a pair of two-terminal operational amplifiers, the first of which has inverting and non-inverting inputs, and the second of which has the current input and a second input connected in common with an input to the first amplifier. Internal feedback circuits provide the desired current conveyance. The circuit may be implemented either with mutually discrete two-terminal operational amplifiers, or these elements may be merged into a single unified circuit. Applications include a general purpose adder/subtractor circuit, an inverting gain amplifier, an instrumentation amplifier, integrators and differentiators.

Abstract: An amplifier circuit is described comprising a transconductance amplifier in series with a voltage gain stage. A compensation capacitance coupled across the voltage gain stage includes a capacitance whose value is dependent upon the output voltage of the voltage gain stage so as to optimize amplifier stability over a wide range of output voltages.

Abstract: A microwave-frequency feedback amplifier circuit has a cascode amplifier with a first field-effect transistor (FET) having a gate for receiving a signal to be amplified, a source coupled to a reference voltage, and a drain. A second FET has a source coupled to the drain of the first FET, a source coupled to the reference voltage, and a drain. A transformer includes a first inductor with a first terminal coupled to the drain of the second FET and a second terminal for outputting an amplified input signal. A second inductor has a first terminal coupled to the second terminal of the first inductor, and a second terminal coupled to the reference voltage. A feedback circuit couples the drain of the second FET to the gate of the first FET.

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: The invention relates to a signal-shaping network comprising a differential amplifier (G) having an output and an inverting (A) and a non-inverting (B) input between which a signal source (S) is connected. When a differential amplifier is used particularly for the measuring of very weak biosignals, interference signals may easily make the measuring completely impossible. In the signal-shaping network according to the invention, interferences have been eliminated in such a way that an integrating feedback circuit (1a; 1b) is connected between the output and one input of the differential amplifier (G) and/or a derivative feedback circuit (2a) is connected between the output and the other input of the differential amplifier. In this way an adaptive differential amplifier is achieved which attenuates slow interference signals and/or rapid interference signals.

Abstract: The present application relates to an active bandpass amplifier comprising a single stage operational amplifier, a bridged "T" network single frequency elimination filter in the negative feedback path of the amplifier and a phase shift correcting capacitor associated with the bridged "T" network single frequency elimination filter to effect a phase shift sufficient to maintain an appropriate feedback such that the amplifier is stable. The bridged "T" network single frequency elimination filter in conjunction with the circuit capacities and phase shifts in the integrated circuits introduces a phase shift which would result in the amplifier oscillating when the network is placed in the feedback path and the corrective capacitor effects a corrective phase shift to render the amplifier stable.

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: 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: 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 tunable drain-biased transresistance (DBT) device for generating accurate linearly variable RC values employs first and second matched MOS transistors connected in first and second series circuits with third and fourth matched MOS transistors, respectively, across the terminals of a source of supply voltage. A differential amplifier has first and second input terminals connected to respective drain electrodes of the first and second MOS transistors and an output coupled via a feedback circuit to at least one of its input terminals. A pair of signal input terminals are connected to the gate electrodes of the first and second transistors so that said input terminals operate into a high impedance. A source of adjustable bias voltage (V.sub.B) is connected in common to the gate electrodes of the third and fourth transistors thereby to supply adjustable bias currents (I.sub.B) to the drain electrodes of the first and second transistors so as to bias these transistors into their triode regions.

Abstract: A third-order all-pass network for a delay circuit is formed by four coupled transconductors (G.sub.10 to G.sub.13) which are each represented by two transistors whose bases constitute the inputs and whose collectors constitute the outputs of the transconductor. A first input of these transconductors (G.sub.10 to G.sub.13) is connected to ground (3). Between the second inputs (25,26) of the first transconductor (G.sub.10) and the second transconductor (G.sub.11) a first capacitor (C.sub.1) is arranged, between the second inputs (26,27) of the second transconductor (G.sub.11) and the third transconductor (G.sub.12) a second capacitor (C2) is arranged, and between the second inputs (27,28) of the third transconductor (G.sub.12) and the fourth transconductor (G.sub.13) and a third capacitor (C3) is arranged. Further, a fourth capacitor (C4) is arranged between the second inputs (25,27) of the first transconductor (G.sub.10) and the third transconductor (G.sub.

Abstract: An audio signal conditioning system comprising a power supply for providing a direct current having a predetermined voltage; input gain control device for receiving the audio sound output signals and for controlling gain; a first transistor amplifier connected to the input gain control, the first transistor providing a first amplified output signal from the collector thereof; a second transistor amplifier connected to the first transistor amplifier for receiving amplified signals from the first transistor amplifier and providing a second amplified output signal from the collector thereof; a negative feedback circuit between the first transistor amplifier and the second transistor amplifier for transmitting negative feedback signals from the emitter of the second transistor amplifier to the base of the first transistor amplifier and a regenerative feedback circuit and an associated tone control circuit between the first transistor amplifier and the second transistor amplifier for transmitting regenerative feed

Abstract: The feedback control loop of the common-emitter output transistor stage of a low dropout voltage regulator imcorporates a staggered pole-zero network, which effectively introduces an incremental reduction, or rolloff, in gain, and an accompanying reduction in phase shift with increase in frequency, so that, at the unity gain point of the transfer characteristic, there is still substantial phase margin, thus preventing the circuit from being driven into oscillation. The RC load pole location can vary widely and stability is maintained. The network is configured as a staggered resistor-capacitor network comprised of plural resistor-capacitor circuits coupled in cascade between the output of the feedback error amplifier and the input of a buffer amplifier the output of which drives the base of the output stage transistor in order to offset loading effects of the transistor base on the staggered pole-zero network.

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 high gain RF amplifier comprises first and second common-emitter transistor amplifier stages coupled in cascade between an RF input terminal to which RF signals to be amplified are applied and an RF output terminal from which amplified RF signals are derived. A first RF signal feedback path is coupled between the emitter of the second common-emitter transistor amplifier stage and the RF input terminal. A directional coupler is connected to provide a second, high reverse isolation RF signal feedback path between the output terminal and the emitter of the first common-emitter transistor amplifier stage. The first RF signal feedback path preferably comprises a resistor-capacitor circuit coupled in series between the emitter of the second common-emitter transistor amplifier stage and the base of the first common-emitter transistor amplifier stage.

Abstract: A fitter comprising a first (R.sub.1) and a second (R.sub.2) resistor arranged in series between an input terminal (5) for receiving an input voltage (v.sub.i) and the input (2) of an amplifier. The amplifier (1) comprises a transistor (T.sub.1) whose base is coupled to the input (2), whose emitter is coupled to a first output (3) and via a current source (I.sub.1) to ground, and whose collector is coupled to a second output (4) and via a third resistor (R.sub.3) to the positive power-supply terminal. A first capacitor (C.sub.1) is arranged between the junction point (6) between the first resistor (R.sub.1) and the second resistor (R.sub.2) and the first output and a second capacitor (C.sub.2) is arranged between the input (2) and ground. A signal having a second-order low-pass characteristic is taken from the first output and a signal having a second-order high-pass characteristic is taken from the second output.

Abstract: In an amplifier arrangement, including a transadmittance circuit having an input coupled to an input of the amplifier arrangement, and a transimpedance amplifier having an input coupled to an output of the transadmittance circuit and an output coupled to an output of the amplifier arrangement, in which the transfer function modulus of the transimpedance amplifier has a first-order decrease above a first frequency F1 and a second-order decrease above a second frequency F2, which transimpedance amplifier is negatively fed back by means of a negative current feedback circuit, the negative current feed back circuit is constituted by a negative feedback impedance whose inverse of the transfer function modulus below the second frequency F2 is smaller than the transfer function modulus of the transimpedance amplifier and which transfer function modulus has a first-order increase above a third frequency F3 so that the transfer function modulus of the negatively fed back transimpedance amplifier has a first-order decr

Abstract: A wide band low noise amplifier for metric waves, including a transistor connected by its emitter to the ground of the amplifier through two secondary windings, connected in series, of a first and second transformer, and coupled between its base and its emitter by the primary winding of the first transformer, one end of the primary winding of the second transformer being connected to the collector of the transistor, the output signal of the amplifier being taken from all or part of the primary of the second transformer and the number of turns of the secondaries of the transformers being very low so as to limit the leak inductance, which amplifier further comprises a first resistor connected in series with the two secondary windings and a second resistor connected between the output of the amplifier and the transistor base.

Abstract: A third-order all-pass network for a delay circuit is formed by four coupled transconductors (G.sub.10 to G.sub.13) which are each represented by two transistors whose bases constitute the inputs and whose collectors constitute the outputs of the transconductor. A first input of these transconductors (G.sub.10 to G.sub.13) is connected to ground (3). Between the second inputs (25,26) of the first transconductor (G.sub.10) and the second transconductor (G.sub.11) a first capacitor (C.sub.1) is arranged, while between the second imputs (26,27) of the second transconductor (G.sub.11) and the third transconductor (G.sub.12) a second capacitor (C2) is arranged, and between the second inputs (27,28) of the third transconductor (G.sub.12) and the fourth transconductor (G.sub.13) a third capacitor (C3) is arranged. Further, a fourth capacitor (C4) is arranged between the second inputs (25,27) of the first transconductor (G.sub.10) and the third transconductor (G.sub.

Abstract: A high gain bandpass amplifier for amplifying low frequency, low level signals ouptut from ceramic infrared sensors. The amplifier includes an input capacitor having a pair of terminals with one of the terminals for receiving the infrared sensor output signal. A first MOS operational amplifier having inverting and noninverting inputs and an output, has its inverting input connected to the other terminal of the input capacitor. A first feedback network is coupled between the first amplifier inverting input and output. A resistor having a pair of terminals has one terminal connected to the first amplifier output. A second MOS operational amplifier also having inverting and noninverting inputs and an output has its inverting input connected to the other terminal of the resistor. The noninverting inputs of the first and second amplifiers are connected together and receive the reference voltage. A second feedback network is coupled between the second amplifier inverting input and output.

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: A filter adjustment apparatus adjusts the properties of a filter by changing, for example, the circuit constants of a filter connected in series with a signal processing circuit to correspond with desired optimum properties of the filter. The state of the signal processing circuit is changed to a state not affecting the filter adjustment, to thereby eliminate the influence of the signal processing circuit on the filter characteristics, to facilitate and increase precision of the filter adjustment.

Abstract: A radio circuit apparatus for broadcast frequencies promotes micro miniaturization and avoids the production of unwanted radiation by incorporating tunable R-C circuits in place of inductive elements. The apparatus provides simultaneous tuning of RF, mixer, and local oscillator circuits by coupling variable radiation levels to a plurality of radiation-sensitive resistor elements in each circuit. In one configuration of the tuner portion, a rod having a radioactive coating is mounted coaxially within a cylindrical parallel array of resistor elements, the elements being connected in tunable Wien-bridge and/or twin-T circuits. An axially movable, cylindrical shutter is interposed between the rod and the resistor elements for variably blocking the radiation from the rod for tuning the circuits.

Abstract: A detector for airborne alpha radiation includes an ion pulse collecting chamber connected to a phase shifted, 100% negative feedback electrometer circuit. The ion pulse chamber includes a probe surrounded by an 80% open grid, with the spacing between the probe and the grid providing no greater than about 50 ms transit time before collection and having a capacitance of less than 1 pf. The field strength between the probe and the grid is less than 10 V/cm. The ion pulse chamber is contained within a vented cabinet. If it is desired to count only radon, a negative potential with respect to the grid may be applied to the cabinet to collect positively charged free ions. Alternatively, the cabinet wall can be made positive with respect to the grid to create a potential-well at or near the grid to provide an enhanced daughter detection mode. If the cabinet wall and the grid are the same potential, both radon and daughter alpha radiation are detected.

Abstract: An amplifier having a cascade circuit which comprises a first and a second transistors connected in cascade. To suppress the signal voltage change at the common connecting node between the first and the second transistors, the gates or the bases of the two transistors are commonly connected to the signal input terminal.

Abstract: In a filter arrangement, a first junction capacitor is arranged between the inverting output and the non-inverting input of a fully balanced amplifier and a second junction capacitor is arranged between the non-inverting output and the inverting input. Additionally, a first resistor is arranged between a first input terminal and the non-inverting input and a second resistor is arranged between a second input terminal and the inverting input. A first current source is connected to the non-inverting input and a second current source is connected to the inverting input. The current sources produce the reverse voltages for the junction capacitors across the resistors to define the capacitance values of these capacitors.

Abstract: An analog two pole filter is provided which uses a single amplifier to implement a predetermined transfer function. The filter has a differential input and converts the two inputs to a single output utilizing the same amplifier which performs the filtering function. By coupling a capacitor across the differential input and utilizing the differential aspect of the input signals, the capacitor may be implemented with half the capacitance otherwise required to implement the predetermined transfer function, thereby minimizing circuit area.

Abstract: In a filter arrangement having a transconductance circuit, a first capacitor is arranged between the inverting output and the non-inverting input of a balanced amplifier and a second capacitor is arranged between the non-inverting output and the inverting input. The outputs of a transconductance circuit (transconductor) are connected to the non-inverting input and the inverting input, which transconductor converts a balanced input voltage applied to the inputs into a balanced output current, its transconductance being variable by means of a variable current source. Further, the transconductor is loaded by a load circuit comprising a first current-source transistor and a second current-source transistor whose common base is connected, via a diode, to the junction point between two resistors arranged between the outputs of the transconductor.

Abstract: A filter comprises an amplifier circuit arrangement having a signal input (1) and a signal output (8) and a coupling (36) between a point (37) on a signal path (39) to the signal input and a point (38) on a signal path from the signal output. The amplifier circuit arrangement comprises an inverting amplifier (6) to the input (5) of which the signal input (1) is connected via a series impedance (7), e.g. a resistor. A feedback impedance (9), e.g. a capacitor, connects the amplifier output (8) to its input so that this input constitutes a virtual ground. The phase relationship between the input and output signals of such an arrangement changes from inverting to non-inverting at frequencies at which the gain of the amplifier drops to below unity because of forward feed through the feedback impedance (9), thereby upsetting the phase relationship between the signals passing through the arrangement and those passing through the coupling. Accordingly, a further impedance (10), e.g.

Abstract: A frequency-compensated transistor feedback amplifier provides relatively wide bandwidth and relatively large phase and gain margins, irrespective of the transconductance of the transistors in the amplifier. Each one of three preferred embodiments (10, 50, 104) of the invention includes a transconductance stage (20, 68, 68) and an amplifier stage (12 and 14, 54, 54 and 14). The transconductance stage delivers an input signal to the amplifier stage, which produces an amplified replica of the input signal. A feedback capacitor (24, 88, 24 and 88) connected between the output and the input of the amplifier stage provides dominant pole compensation by which the magnitude of the loop gain diminishes by 6 dB/octave with increasing frequency. The capacitor provides a forward feedthrough path for any residual portion of the input signal so that the residual portion arrives at the output of the amplifier stage in substantially the same phase relation with that of the output signal of intermediate frequency.

Abstract: A high frequency active filter is presented having an amplifier having an en loop gain between one and three which is provided with appropriate electrical components of appropriate values for generating the desired filter configuration of pole-zero pairs with no intentional connection between the negative input terminal of the amplifier and the output terminal of the amplifier.

Abstract: In an amplifier for a high frequency signal used to amplify a signal having a high frequency in a television tuner, a receiver for satellite broadcasting, and the like, at least two stages of dc-coupled grounded-emitter type amplifiers (Q.sub.1, Q.sub.2) are configured in an integrated circuit, a resistor (R.sub.13) is connected between an emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage and the grounding, a terminal for connecting an external device is disposed to be connected via a bonding wire to the emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage, and a filter circuit (11) including an inductance of the bonding wire and developing a low impedance for a particular frequency is disposed between the terminal and the external grounding.

Abstract: An FET amplifier circuit is provided capable of minimizing the phase change of signals which pass through the circuit. Further, an FET amplifier circuit is provided capable of protecting the circuit against the effects of over-amplitude input signals with the phase change minimized.

Abstract: A post-equalizer and pre-equalizer circuit for use in communicating between nodes in a Pulse Amplitude Modulated (PAM) digital or analog communication system is described. The post-equalizer circuit comprises a first variable zero circuit, a second variable zero circuit, and a gain shaper circuit wherein the gain and frequency location of the zeros in the zero circuits combined with the gain of the gain shaping circuit are simultaneously controlled by a control circuit which generates a control voltage which is a monotonically increasing function of cable loss. In the case of a PAM digital communication system, the control voltage generates a signal equal to the difference between the equalized signal and the original transmitted signal which is used to vary the resistance of voltage variable resistors in the form of FET's in each of the zero circuits and gain shaper circuits.

Abstract: An integrable, high frequency superlinear amplifier and its fabrication method is disclosed which is related to the basic amplifier fabrication field having negative feedback and signal conversion. The three stage amplifier design involves a first and second stage which have a narrow bandwidth response and a third amplifier stage with a larger or wider bandwidth response. The bandwidth of the wide bandwidth stage is such that when the gain curve for the two narrow bandwidth stages passes through the -6dB point at a first frequency then the peak point of the wide bandwidth stage is located at a second frequency higher than the first frequency. The wide bandwidth stage utilizes a single capacitor so that the resulting curve of the three stages has an approximately flat portion below the zero gain point. The impedance of the network is adjusted to a desired value through a feedback configuration.

Abstract: An operational amplifier suitable for inclusion in an integrated circuit device operating as a transceiver at a coaxial media interface to a network meeting IEEE 802.3 standards. To be included in an integrated circuit package the operational amplifier must have low-power consumption and yet generate up to 80 mA of current onto the network. A design method achieves this goal, producing an operational amplifier having three independently-positioned, isolated, poles. A current generator and level shifter is employed with the operational amplifier which generates a current precisely proportional to a "collision" reference voltage, the current is compensated for changes in temperature and for variations in transistor gain (hFE). A very wide band level shifter matches the current generated to the requirements of the operational amplifier so that 10% to 90% changes in current generated by the op amp can occur in 1/2 to 3/4 of a nanosecond, yet the level shifter does not consume much power.

Abstract: An active low-pass filter especially suitable for inclusion in an integrated circuit and capable of operating at frequencies up to at least f.sub.T /.beta. of transistors within the filter. A bootstrap circuit is coupled to the emitter follower to reduce the capacitive effect of the emitter follower on the passed signal and to guarantee precision pass band gain match among the filters. A plurality of active filters may be connected across the signal path to provide a selection of bandwidths. A filter is switched into and out of the signal path by selectively enabling and disabling its current source.

Abstract: A circuit useful as a voltage tunable resistive element comprises four matched MOS transistors in which each of the first and second have their drains interconnected to a first input terminal and each of the third and fourth have their drains interconnected to a second input terminal, the first and third have their sources interconnected to a first output terminal and the second and fourth have their sources interconnected to a second output terminal, and the first and fourth have their gates interconnected to a first control terminal and the second and third have their gates interconnected to a second control terminal. A continuous-time integrator is described which includes such a resistive element.