Showing papers on "Output impedance published in 1983"

Optimum Design of 3-Db Branch-Line Couplers Using Microstrip Lines

Abstract: A computer-aided design is described that makes it possible to reduce the internal impedance levels of branch-line couplers so that they may be physically constructed by microstrip lines, where the Fletcher-Powell search method has been used to optimize the design. Because microstrip lines are severely restricted in their usable impedance range, the 3-dB couplers presented here should be useful for numerous balanced-type components such as balanced mixers. The validity of the design has been experimentally verified in the microwave and millimeter-wave region.

Load impedance detector for audio power amplifiers

Abstract: Disclosed is a load impedance detector for detecting a variation of the load impedance of a single-ended push-pull amplifier having a pair of first and second transistors, the emitters of which are interconnected by a pair of series-connected first and second resistors forming a first node to which the load impedance is connected Third and fourth resistors are connected in series to the emitter of the first transistor to form a bridge circuit with the first resistor and the load impedance so that the third and fourth resistors define a second node therebetween A voltage difference between the first and second nodes is detected by a differential circuit which is responsive to there being a simultaneous presence of a first state in which the detected voltage difference is higher than a first predetermined value and a second state in which the potential across the load impedance is higher than a second predetermined value for generating an output signal This output signal is utilized for controlling the level of the voltage supplied to the amplifier to compensate for the impedance variation

Noise Source Equivalent Circuit Model for Off-Line Converters and its use in Input Filter Design

Abstract: As a s t e p toward d e s ig n in g a f am ily o f power l i n e i n t e r f e r e n c e f i l t e r s d e d i c a t e d f o r o f f l i n e sw i t c h in g mode power s u p p l i e s , an e q u i v a l e n t c i r ­ c u i t was developed t o d e s c r i b e t h e t y p i c a l c h a r ­ a c t e r i s t i c s of t h e n o i s e source e x i s t i n g a t th e AC t e r m i n a l s of t h e s e s u p p l i e s . The model uses l i n e a r e l em en ts t o p r e d i c t t o a f i r s t o rd e r th e behav io r o f RFI f i l t e r s as a p p l i e d t o sw i t c h in g mode power s u p p l i e s . C o n s o l i d a t i n g b a s i c f i l t e r and matching c i r c u i t a n a l y s i s with t h e e q u i v a l e n t n o i s e s ou rce c i r c u i t f a c i l i t a t e s t h e development o f an optimum RFI f i l t e r f o r sw i t ch in g mode power s u p p l i e s .

Ground tether continuity monitor

Abstract: A monitor for sensing any break in electrical continuity between a body and earth when the body is coupled to earth by way of a grounding tether used to prevent build-up of static charges on such body. The monitor includes an oscillator circuit for generating A.C. output voltages which are adapted to actuate an alarm. Body capacitance and resistance are coupled by way of the tether across an impedance network either in the tuned circuit determining oscillator frequency or in the output load thereof whereby the resistance or inductance of the impedance network provides the path to ground for the body through its tether. With body capacitance and resistance components of the total impedance, variable elements in the impedance network are adjusted to diminish the circuit output voltage below the threshold voltage required to actuate the alarm when continuity exists while developing an output voltage level sufficient to actuate the alarm when a break in continuity occurs.

Electronic hybrid having synthesized impedance circuitry

Abstract: An electronic hybrid circuit for coupling a two-wire communication path to a four-wire communication path includes amplifier circuits having a reactive feedback path such that the output impedance of each amplifier is approximately zero ohms at d.c. and is a predetermined value at audio frequencies. The amplifiers are arranged to provide battery and voice signal injection on the two-wire path.

Measurement of the acoustic internal source impedance of an internal combustion engine

Abstract: The standing wave tube technique has been adapted to measure the acoustic internal source impedance of an internal combustion engine. In order to implement this technique an extensive experimental facility was designed and constructed and simple test cases were evaluated for validity. In addition an adaptation of the standing wave tube method incorporating a random signal as the external driver sound source and digital data analysis techniques were introduced to reduce the experimental difficulty and time consumption. Normalized specific acoustic impedance data at a constant engine speed of 2200 rpm show little change with varying engine load conditions. Similar data at a constant engine load condition of 254‐mm Hg exhibit more significant dependence on engine speed.

Acoustic impedance measurement

Abstract: An open-ended acoustic impedance tube is abutted against a material having a known acoustic impedance and a standing wave pattern is established in the tube. A first apparent impedance of the material is derived based on the standing wave pattern. A correction factor is computed based on the known impedance and the first apparent impedance. The open-ended impedance tube is then abutted against a sample material and a second apparent impedance is derived. The actual impedance of the sample is inferred from the second apparent impedance and the correction factor.

Errors in four-electrode impedance plethysmography.

Abstract: The errors in electrical impedance plethysmography are not well known In the paper errors due to inadequate instrumentation, improper electrode application, and physiological changes have been analysed Minimum electrical requirements for a general purpose four-electrode instrument are: (a) input impedance of voltage-sensing circuit+4 kΩ; (b) output impedance of constant-current source+20 kΩ; (c) cmrr+400; (d) common-mode input impedance+40 kΩ; and (e) apparent change of resistance due to noise×0·5 mΩ All electrodes should be separated by at least one limb diameter Changes of electrode impedance due to pressure produce negligible error in a four-electrode configuration The only way to eliminate the large subject-motion errors is to eliminate the motion Changes of blood resistivity with velocity produce an error estimated at 10 per cent A repeatability test on the upper arm gave a standard deviation of 6 per cent of the mean

Saw stabilized oscillator with controlled pull-range

Abstract: An oscillator including an active device (38), a surface acoustic wave resonator (40) connected in a feedback relationship to the active device and an impedance matching circuit is disclosed. The impedance matching circuit in one arrangement is an output impedance matching circuit including an inductor (46) connected in the feedback loop to the output of the active device. In another arrangement, the impedance matching network is an input impedance matching network including an inductor (42) connected in the feedback loop to the input of the active device. In another arrangement of the invention, a varactor diode (60) is connected in the feedback loop and is controlled by a reverse voltage which changes the capacitance of the diode, adjusting the frequency of the oscillator.

A Range of Body Impedance Values for Low Voltage, Low Source Impendance Systems of 60 HZ

Abstract: The severity of electric shock to humans from low voltage (60 Hz) low source impedance systems is dependent on many variables. These factors include the body impedance, current magnitude and duration, voltage and frequency of the circuit, and the current path traversed in the body. Several authors have investigated safe voltage and current limits that humans can withstand. As a result, thresholds have been established of the body's response to 60 Hz alternating current of a few milliamperes in low voltage systems. This report evaluates the many published findings as a means of recommending a range of body impedance values. While the authors have endeavored to present as comprehensive a review as possible, a subject of this nature precludes a completely exhaustive literary search.

Thyristor voltage limiter for current source inverter

Abstract: A voltage limiter for protecting the thyristors of a current source inverter, also known as a controlled current inverter, wherein the limiter includes a circuit for sensing the respective voltages directly across at least one but preferably across each of the thyristors in the inverter and generating a signal corresponding to the highest value and a regulator circuit which is operable in response to the difference between the highest value signal and a reference signal corresponding to a safe operating voltage for the thyristors in the inverter, to modify the thyristor gating angle of those thyristors which control the current in the inverter. The voltage limiter thus reduces the current carried by the inverter thyristors when the highest voltage across the inverter thyristors exceeds the reference signal, and thereby reduces the amplitude of any commutating spike voltage in the voltage applied across the thyristors. This permits full utilization of the inverter rating while requiring no adjustment for source impedance, line voltage, or commutating capacitance.

Impedance measurement in 4-wire to 2-wire converters

Abstract: An oscillating input signal is applied to the 4-wire input terminals which is monitored while the 4-wire output terminals and the 2-wire terminals are also monitored. This procedure is performed with a first known reference impedance connected across the 2-wire terminals and then repeated with a second reference impedance similarly connected. A plurality of input frequencies may be applied over the range of 400 Hz to 4000 Hz.

Reference Waveform Flat Pulse Generator

Abstract: The NBS Reference Flat Pulse Generator (RFPG) is used to transfer dc voltage and resistance standards to the nanosecond domain. It provides a step amplitude of 1.000 V (open circuit) from a source impedance of 50.0?. The transition duration is 600 ps, and all perturbations are damped out to less than ±10 mV within 5 ns. It can also be used as a time interval transfer standard.

Inverter Output Voltage Waveform Closed-Loop Control Technique

Abstract: Inverter output impedance which depends mainly on the AC output filter is lowered by applying a closed-loop control technique to the voltage waveform shaping. In consequence, inverter output dynamic characteristics are drastically improved; The transient voltage variation and waveform distortion are lowered. This paper explains a noble control system and shows experimental results.

Receiving circuit for a data transmission system

Abstract: A data transmission system for transmitting and receiving data over a transmission line includes a receiving station having a receiving circuit for simultaneously detecting current and voltage signals including the data in the transmission line and applying these signals to a common output impedance, so that an output voltage signal developed across the output impedance will have a sufficient signal level irrespective of the value of other load impedances on the transmission line.

Temperature control device of fuel cell

Abstract: PURPOSE:To detect the cell temperature from outside by measuring the internal impedance of a cell. CONSTITUTION:An impedance measuring device 1 is connected between a fuel cell FC and a load L and is composed of a DC ammeter 2, a DC voltmeter 3, an AC voltmeter 4, and a constant-frequency, constant-current AC generator 5. The AC generator 5 feeds currents in parallel to the cell FC and the DC load L, and the AC voltage displayed on the AC voltmeter 4 is generated by the resultant impedance Zr of the internal impedance Z of the fuel cell FC and the load resistance R. Accordingly, individual detection signals from the impedance measuring device 1 are inputted to a control unit 6 to calculate the internal impedance Z of the cell. The value of this Z depends on the cell temperature, thereby this Z is used as an output signal to regulate a damper 7 and a blower 8 so as to control the feed air temperature and air quantity.

Component video interconnection apparatus

Abstract: Apparatus for interconnecting a component entertainment system including a bi-directional signal bus for interconnecting some of the components comprises a first switch unit having one input adapted to be coupled to the bi-directional signal bus, at least one other input adapted to be coupled to receive signal from a component not connected to the signal bus and a common output. A second switch unit has one input adapted to receive signal from the component not connected to the signal bus. A signal driver has its input coupled to the output of the second switch unit and its output coupled to the input of the first switch unit adapted to be coupled to the signal bus. The output impedance of the signal driver serves to terminate the signal bus in its characteristic impedance when the driver does not supply signal at its output.

Focusing voltage output circuit for cathode ray tube

Abstract: In a focusing voltage output circuit for a cathode ray tube, a variable impedance circuit is connected in series with a variable resistor for adjustment of focusing voltage. The impedance of the variable impedance circuit is changed in response to a video luminance signal or a beam current to change the focusing voltage so as to optimize the focus tracking characteristic.

Level converting circuit

Abstract: PURPOSE: To decrease power consumption by not applying negative feedback to the 1st CMOS inverse amplifier circuit amplifying a signal and using the separate 2nd CMOS inverse amplifier circuit so as to generate an automatic bias voltage. CONSTITUTION: A resistor for negative feedback having been connected to an input/output of the 1st CMOS inverse amplifier circuit A 1 is removed so as to increase the gain and also to improve the output impedance. Then the 2nd CMOS inverse amplifier circuit A 2 is connected to the input of the 1st CMOS inverse amplifier circuit A 2 is connected to the input of the 1st CMOS inverse amplifier circuit A 1 , the input/output of the 2nd CMOS inverse amplifier circuit A 2 is connected with a low impedance and a proper automatic bias voltage is given by the 2nd CMOS inverse amplifier circuit A 2 . COPYRIGHT: (C)1985,JPO&Japio

Low power consumption, high speed CMOS signal input circuit

Abstract: A signal input circuit particularly well suited for use in MOS integrated circuits. The signal input circuit includes: and input gate circuit for receiving an input signal and an enable control signal, and for generating an output signal equal to the input signal when the enable control signal is in an "enable" state, and for providing a high output impedance when the enable control signal is in a "disable" state; and a holding circuit coupled to an output of the input gate circuit and to receiving the enable control signal, for holding, during the disable state, the output state of the input gate circuit immediately before the enable control signal changes to a disable state, the output impedance being high when the enable control signal is in an enable state.

General feed-forward input filter compensation method

Abstract: For several reasons a switching regulator is always preceeded by an input filter, and this impairs all essential parameters of the regulator. The extended injected- absorbed current analysis method culminates in a truly general switching cell model, which, embedded in a closed-loop structure, results in a general model of a switching regulator. This model, preceeded by an equivalent filter network, consisting of an equivalent voltage generator and an output impedance, is analysed and the results demonstrate that a suitable feed-forward loop can entirely eliminate the undesirable effects of the filter. It is shown that the compensation depends on the cell parameters. Guidelines for future investigations are formulated.

Gain control circuit for obtaining a constant output signal amplitude by attenuating an input signal amplitude

Abstract: A gain control circuit is disclosed. In accordance with the preferred embodiment of the invention, a negative feedback amplifier is connected between a reference voltage and a variable impedance circuit which controls the voltage to the input of a signal amplifier whose output defines the desired output voltage. The variable impedance circuit varies the input voltage to the signal amplifier as a function of the level of the output voltage appearing at the output of the signal amplifier. The output impedance of the negative feedback amplifier is chosen such that an A.C. signal appearing at its output end can be sufficiently attenuated. As a result, the input impedance to the variable impedance circuit is negligibly small with respect to an A.C. signal. As a result, the amplitude of the input signal is varied over a wide range in response to the impedance of the variable impedance circuit.

On the Output Resistance of Self-Checking Voltage Dividers

Abstract: This paper deals with the computation of the variable output resistance of Cutkosky's self-checking binary voltage divider. For an N-bit divider, the maximum output resistance was found to increase with N at the rate of N/9 times the divider's characteristic input resistance. To increase the divider's resolution while limiting its output resistance, a binary potentiometer as a termination is suggested.

Multiple display control apparatus for a television receiver

Abstract: A multiple display control apparatus for a television receiver used for displaying a plurality of signals on a display tube. In a case of switching a first signal output and a second signal output of a signal process circuit are switched by switching circuits, when the two output signals are about equal in the brightness level to each other, the picture is very indistinct. Thus, the first signal level is lowered by means of gain control circuits, the characteristic thereof depending on an output impedance of the signal process circuit and resistances. The control signals for switching and gain control are superposed each other as one signal, so that only one line is used for control signal.

Square wave exciting electro-magnetic flow meter converter

Abstract: PURPOSE:To detect the flow-out of liquid in a detector by providing a three- way selection switch that shuts off an exciting circuit by means of giving a mimic signal that is synchronized with the exciting signal to the exciting circuit and providing a comparator that takes as a standard voltage the output of a converter at the time where there is a fluid. CONSTITUTION:A square wave exciting electro-magnetic flow meter converter consists of a high input impedance differential A/C amplifier 11, later stage amplifier 12 that processes the output by calculation. Further, a mimic signal generating circuit that consists of a switch 14 such as FET that is turned on and off in synchronization with the exciting signal, D/C standard voltage source 13, and resistor 15 for current limitation is provided. Also a 3-circuit select switches 19a-c and a comparator 21 are provided. The standard voltage 20 is established equal to the output value of an amplifier 12 that is obtained by input of a mimic signal when the switches 19a-c are operated and a fluid exists in the measurement pipe 3 and the output impedance of the electrode 4 is at maximum, and it is possible to make a comparator 21 sends a signal that indicates that there is no liquid in the measurement tube 3.