Showing papers on "Output impedance published in 1969"

Ekg amplifying electrode pickup

Abstract: An amplifying electrode pickup for an electrocardiograph (EKG.) device consisting broadly of an impedance converter integrated amplifier circuit potted in a metal shell. The integrated circuit is biased by a nanoamp electrical current. The EKG. signal is sensed by a small sensor plate or disc positioned in a boot or cover and is electrically insulated from the shell. The circuit has a very high input impedance to minimize the effect of skin contact resistance changes, and a very low output impedance to minimize noise pickup by the signal line between the electrode and the EKG. electronics. Electronic circuitry in the potted metal shell also includes a diode voltage clamp and decoupling RC circuits. A multiconductor cable provides shielding, conducts power to the electrode, and transmits the signal from the electrode through an integral coaxial cable. Because of the low (nanoamp) biasing current, signal traces of numerous separate electrodes can be simultaneously recorded without exceeding the maximum permissible current through the human body as established by the American Heart Association.

A silicon MOS magnetic field transducer of high sensitivity

Abstract: A structure has been devised which converts magnetic flux density change to a change in output current. The structure is essentially a P-channel MOST with the drain diffusion split into two halves. A magnetic field normal to the silicon surface deflects device current towards one half-drain. By operating the MOST in the "pinched-off" mode (V DS > V GS -V T ) the output impedance is made high, so that large output voltage swings may be obtained. A theoretical study of the voltage and current distributions in the MOST channel has given data on the influence of device geometry on sensitivity. Experimental results indicate a linear relationship between output current and magnetic flux density, and an unexplained nonlinear variation of output with device current. Comparison of experimental results with theory indicates a carrier Hall mobility in the channel of 116 cm2/V.s.

Impedance matching network for plasma-generating apparatus

Abstract: A passive impedance-matching network specifically designed to provide an interface between a fixed radio frequency power output of a generator and the capacitive electrodes of the gaseous plasma chamber of a plasma-generating apparatus, the network having the particular characteristic of providing a close impedance match over a relatively wide changing impedance range of the plasma in accordance with a known program.

Fundamentals of Network Analysis

Abstract: Equivalent circuits for electronic devices will be shown to consist of simple current or voltage generators, together with impedances or admittances. In Chapter 1, we found that such devices could only operate correctly if they were connected to suitable load and bias circuits consisting of impedances or admittances. In addition, any signal to be amplified was supplied from an a.c. current or voltage source together with its associated impedance or admittance.

Piezoelectric transducer with improved sensing circuit

Abstract: An improved sensing circuit particularly adapted for use with a piezoelectric transducer or the like, which transducer is characterized by its extremely high internal impedance. The transducer is disposed in a normally balanced input circuit so that there is effectively zero current flowing through the transducer when it is not activated. A unity-voltage-gain, highcurrent-gain amplifier is biased to its linear conduction operating point so as to present an extremely high dynamic input impedance to the output signal from the transducer. The amplifier output is applied to trigger a variable threshold, variable current output control circuit having a relay as an indicating device.

Mos bipolar push-pull output buffer

Abstract: An output buffer for an MOS integrated logic circuit which utilizes an output stage comprised of a bipolar transistor and an MOS transistor connected in push-pull configuration is described. The output stage is operated by an MOS control circuit which utilizes an inverter stage with an improved capacitive bootstrap switching network to reduce the magnitude of the gate supply voltage required for positive switching. The circuit is characterized by very low input capacitance, and very low output impedance and thus high capacitive drive capability. A unique connection to ground internally of the integrated circuit is also described which comprises a diffusion made at the same time as the emitter diffusion of the bipolar transistor to provide ohmic contact between an overlying conductor and the substrate which then provides the return path to ground.

Bilateral switch using combination of field effect transistors and bipolar transistors

Abstract: THE FUNCTIONS OF A PLURALITY OF INSULATED GATE FIELD EFFECT TRANSISTORS AND BIPOLAR TRANSISTORS ARE COMBINED IN A COMPOUND DEVICE WHICH IS ELECTRICALLY SYMMETRICAL (BILATERAL) AND WHICH HAS VERY HIGH INPUT IMPEDANCE, LOW OUTPUT IMPEDANCE, AND HIGH CURRENT GAIN. THE DEVICE IS ADVANTAGEOUSLY EMPLOYED AS A BILATERAL COUPLING ELEMENT IN DIGITAL INTEGRATED CIRCUITS, E.G., SEMICONDUCTOR MEMORIES, DC SHIFT REGISTERS, AND DYAMIC SHIFT REGISTERS.

Linear voltage controlled attenuator

Abstract: A voltage controlled attenuator for use in an automatic gain control circuit. The attenuator includes a first transistor having a relatively high output impedance driven by an AC input signal. Its collector output is coupled to the coupled emitter inputs of two common base connected amplifiers which are differentially driven by a control signal to split the output current of the first transistor between them. The output voltage which is attenuated in proportion to the control signal is then taken from the collector of one of the common base amplifiers.

Accurate Impedance Determination of Coupled TEM Conductors

Abstract: A computer-aided finite-difference method is described which can be used to calculate accurately TEM mode impedances of a uniform pair of offset parallel-coupled conductors of arbitrary cross section. The calculated impedance is the average of the lower and upper bounds computed on the mode impedance. For a given computing time, the average impedance is usually found to be more accurate than the one obtainable with either bound alone. The use of a graded mesh is found to provide a smaller separation between the bounds, and hence a smaller maximum error in the average impedance value, in a time much shorter than with the uniform mesh.

Overload protection network for solid state amplifier

Abstract: A network employing auxiliary transistors to protect a solid state amplifier against short-circuited, reactive or abnormally low values of output impedance. Diodes in the network determine the level threshold for energizing the network. A time-constant circuit provides a time delay threshold to prevent nondamaging transients or momentary shorts from energizing the network. When energized, the network arranges bypassing of current from the output transistors, and for a serious abnormality clamps the input of the whole amplifier to ground. Another time-constant circuit determines how long the input shall be clamped to ground and automatically allows recycling of the protective function.

Three-port electrical network

Abstract: A three-port electrical network that has a first port whose impedance is high and whose voltage controls the potential of a second port which has low or zero impedance and through which an independent current flows to reappear at a third port at high impedance which consists of a unity gain amplifier having high input impedance and low output impedance and means for deriving a current related to the current flowing in the output port of the amplifier and means for conveying this current to a third port. The latter two means are current followers energized from constant current sources.

Integrated buffer circuits for coupling low-output impedance driver to high-input impedance load

Abstract: The combination in a common substrate, of a lateral bipolar transistor operated in the common base mode and a field-effect transistor whose source (or drain) electrode is the collector electrode of said bipolar transistor. A signal applied to the emitter of the bipolar transistor causes a current to flow through the conduction channel of the field-effect transistor. The voltage thereby developed at the electrode common to both transistors, even in response to a small signal current, is of sufficient amplitude to drive a high-input impedance load such as other field-effect transistors embedded in the same substrate.

Constant current feedback regulator with adjustable impedance for maintaining constant current

Abstract: A high-voltage power supply has a controlled output oscillator operated from a low-voltage DC source The output voltage of the oscillator is increased by a voltage multiplier A series circuit comprising a high ohmic resistor, a transistor device and an adjustable low ohmic resistor is connected in parallel with the oscillator output, and the transistor impedance is varied to maintain a constant current in the parallel path The voltage developed at the transistor for maintaining a constant current is then used to control the oscillator in order to maintain constant output voltage

Crystal-controlled square wave generator

Abstract: A crystal, a wideband noninverting amplifier with low input and output impedance, a nonphase-shifting limiter circuit, a level shift and buffer output stage provide a square wave voltage output with a high degree of stability. The crystal is connected in a feedback circuit between the output of the limiter circuit and the input of the amplifier. The limiter circuit contains a pair of emitter-coupled transistors neither one of which is driven into saturation. Cutoff of each of the transistors in the pair provides clipping of the sinusoidal voltage peaks provided at the input of the limiter circuit. The generator contains only transistors, resistors, and a piezoelectric crystal, and is therefore especially suited for integrated circuit use.

High frequency transistor structure having an impedance transforming network incorporated on the semiconductor chip

Abstract: This is a semiconductor component having an active semiconductor device formed within a substrate, and an impedance transforming network incorporated on said substrate and coupled to said device so as to reduce the effect of the device lead inductance which is common to both a circuit input and output.

Some effects of the frequency dependence of transmission-line parameters

Abstract: Nonzero earth resistivity leads to line parameters which vary continuously with frequency. Some effects of this variation on transient waveforms are examined. The interaction of the source impedance with the frequency-dependent line impedance is shown to have an effect on the length of line at which the resonant frequency approaches that of the supply. A possible single-phase representation of a 3-phase system is explored.

Solid rectangular and T-shaped conductors in semi-closed slots

Abstract: Previous methods of calculating the internal impedance of rectangular and T-shaped conductors have made arbitrary assumptions about the form of the magnetic field. These have led to inconsistencies. A method is developed which necessitates less restrictive assumptions, thereby removing the inconsistencies. Results are compared for typical conductor sizes.

Integrated circuit periodic ramp generator

Abstract: A temperature stable, low source impedance periodic ramp voltage generator capable of both positive and negative output voltage polarity, or only either one of these, is fabricated in large part as an integrated circuit. The generator comprises the combination of an operational amplifier used as an integrator and a bilateral or unilateral voltage-sensitive switching device, such as a silicon bilateral switch or a silicon unilateral switch, for periodically discharging the feedback capacitor of the integrating circuit.

Frequency multiplier employing input and output strip transmission lines without spatially coupling therebetween

Abstract: A frequency multiplier which features a varactor diode, two coupled transmission lines for input impedance transformation and two coupled transmission lines for output impedance transformation. An intermediate strip conductor is placed between the respective coupled transmission lines so as to provide nonspatially coupling between the lines.

Energy-storage of a prescribed impedance

Abstract: General mathematical expression found for energy storage shows that for linear, passive networks there is a minimum possible energy storage corresponding to a prescribed impedance. The electromagnetic energy storage is determined at different excitation frequencies through analysis of the networks terminal and reactance characteristics.

Ratio Comparisons of Impedance Standards

Abstract: The application of a readily assembled comparator circuit, previously used in the comparison calibration of inductive and resistive voltage dividers, has been extended to cover the comparison of impedance standards. As an example requiring the most stringent performance from the circuit, the comparison of four-terminal inductance standards and their absolute determination in terms of the unit of capacitance have been studied. A data-reduction procedure has been devised to utilize a partial set of pair-wise comparison measurements to establish the absolute scale of inductance from 10 henrys to 500 ?H. A realistic assessment of system errors has been incorporated in the data reduction, which establishes the absolute accuracy at approximately 0.003 percent over the whole range. Determination of the quality factor Q of the inductors to better than 0.2 percent has also resulted from these measurements, principally at 1 kHz.

Mos circuit with bipolar emitter-follower output

Abstract: An inverter for a metal-insulator-semiconductor integrated circuit which utilizes an MOS inverter stage followed by a bipolar emitter-follower stage is disclosed. The inverter stage may have multiple inputs to form a gate. The emitter-follower stage employs a bipolar transistor with an MOS transistor as the load impedance. The size of the output MOS transistor can be changed to provide optimum drive characteristics without redesigning the remainder of the integrated circuit. The emitterfollower output stage provides a very low output impedance, and therefore has the capability to drive higher capacitive loads.

Non-linear impedance means for transistors connected to each other and to a common power source

Abstract: Each of the pair of transistors of a flip-flop storage cell has its collector connected through a nonlinear impedance means to a low constant current source when the cell is in an inactive condition. The nonlinear impedance means for the conducting transistor maintains the ratio of the load impedance means to the base-emitter impedance of the conducting transistor greater than one to maintain the transistors of the cell in the desired bistable state when the transistors are connected to the low constant current source through the nonlinear impedance means.

Transistor impedance converter and oscillator circuits

Abstract: An impedance device adapted to represent various types of impedance which includes a two-transistor circuit equivalent to a single transistor with a common base current amplification factor greater than one and a predetermined impedance element or circuit, and circuits using such an impedance device. This impedance device represents an impedance corresponding to the impedance of the impedance element or circuit multiplied by -( alpha 0-1) where alpha 0 is the equivalent common base current amplification factor of the equivalent single-transistor circuit. One of the circuits using the impedance device is an oscillator which is constructed without an inductance element. Another of the circuits is an inductor having a pure inductance and which is constructed without using any inductance element.

Sonar transmitter system

Abstract: A transmitter arrangement for a sonar active transmit-receive system in which the transducer is controlled to provide a wave front which is more coherent in phase and power by the use of a feedback control signal from the transducers. The transducers are also made to have a constant output impedance which is of a relatively low value.

Video cross bar distributor

Abstract: At the intersection of shielded input cross bars and shielded output cross bars variable gain amplifiers are provided whose gain is externally changeable from zero to a maximum. The variable gain amplifiers comprise a buffer stage designed to keep the input impedance constant regardless of gain changes, and a switching amplifier stage having the variable gain and having an output impedance which is low when the amplifier gain exceeds zero and high when the gain is zero. A mounting arrangement for mounting the components involved is also disclosed.

Matched microwave limiter

Abstract: An improved limiter for microwave circuits to remove voltage applied to a load when the voltage amplitude exceeds a predetermined value without reflections in the circuit. A pair of voltage sensitive switches are connected across a circuit with one switch in series with an insert impedance substantially equal to line impedance. The switches are separated by an impedance inverter to effectively apply a very large impedance across the insert impedance to prevent R-F reflection in the limiting mode.

A Silicon MOS Magnetic Field Transducer of High Sensitivity

Abstract: Abstracf-A structure has been devised which converts magnetic flux density change to a change in output current. The structure is essentially a P-channel MOST with the drain diffusion split into two halves. A magnetic field normal to the silicon surface deflects device current towards one half-drain. By operating the MOST in the “pinched-off ” mode (VDS > VGS - Vr) the output impedance is made high, so that large output voltage swings may be obtained. A theoretical study of the voltage and current distributions in the MOST channel has given data on the influence of device geometry on sensitivity. Experimental results indicate a linear relationship between output current and magnetic flux density, and an unexplained nonlinear variation of output with device current. Comparison of experimental results with theory indicates a carrier Hall mobility in the channel of 116 cm*/V.s.

Multiple series operation of Gunn-effect oscillators

Abstract: The direct series operation of up to ten Xband Gunn-effect oscillators is described with total pulsed power outputs of up to 116W. The configuration used provides a means of increasing the source impedance of large-area low-impedance devices required for high power generation.