Abstract: An amplifier circuit having a variable transmission factor and an effective transmission frequency band delimited by a lower limit frequency is arranged to enable the value of the lower limit frequency to be varied as a function of a control voltage, by including in the circuit an amplifier member and circuit components defining a feedback path connected between the output of the amplifier and an input thereof which is inverting with respect to the output signals of the amplifier, the components defining the feedback path including an electronically voltage-controllable resistor having a control voltage input and a first frequency dependent impedance connected in parallel with the resistor, and the circuit further including a second frequency dependent impedance connected between the inverting input of the amplifier and a point at the circuit reference potential, and a line for supplying the control voltage to the control voltage input of the controllable resistor.

Abstract: An electronic gain control circuit and method are disclosed for providing gain control. The gain control circuit is adaptable for use with differential amplifiers to control the gain thereof and is suitable to be fabricated in monolithic integrated circuit form. The gain control circuit utilizes voltages generated by currents established through diodes to obtain a differential gain voltage to linearly vary the gain of the amplifier. In a preferred form, the amplifier consists of first and second differentially connected transistor pairs with each pair commonly connected to a respective collector of an input differential stage. A constant current source supplies a constant current through a first diode string and is coupled to a common node between the transistor pairs for providing a fixed voltage thereat.

Abstract: A tuned radio frequency amplifier includes signal amplification means having an input and an output and first and second pairs of varactor diodes, each pair having an inductor connected across the anodes and a common tuning voltage supplied to the common cathode. The inductor of the first varactor diode pair provides an input for a signal from an antenna; and the inductor across the second varactor diode pair provides an output for the amplified signal. Means are provided for connecting the input of the signal amplification means to the common cathode of the first varactor diode pair and the output of the signal amplification means to the common cathode of the second varactor diode pair, whereby the range of tuning voltage required for a specified range of tuned frequencies is smaller than if the input and output of the signal amplification means were connected across the anodes of the varactor diode pairs.

Abstract: A direct coupled linear amplifier which employs negative feedback to prov accurate and stable gain to AC as well as DC input signals. It also performs the function of a DC level shifter and can therefore be interfaced with a variety of signal sources. A constant current source added to the summing junction of the negative feedback amplifier enables the adjustment of the DC level of the output and the AC gain of the amplifier, completely independently of one another.

Abstract: A circuit for compensating for the departure from its nominal value of the gain of a current mirror amplifier (CMA). This departure is caused by the presence of base current in one current path of the CMA that is not present in the other current path. The common terminal current of the CMA is sensed and a circuit responsive to this current causes a current to flow at the CMA output terminal that is essentially equal to the aforementioned base currents thereby causing the CMA gain to more closely equal its nominal value. The compensated CMA may be advantageously used in combination with a differential amplifier to reduce the offset voltage of this amplifier.

Abstract: In a direct coupling type power amplifier circuit comprising an input differential amplifier stage, a drive amplifier stage responsive to the output signal of the input differential amplifier stage dc-wise and ac-wise, and a push-pull output amplifier stage responsive to the output signal of the drive amplifier stage dc-wise and ac-wise, the input differential amplifier stage being supplied at one input electrode thereof with an input signal and at the other input electrode thereof with the output of the push-pull output amplifier stage through a negative feedback circuit network, the power amplifier circuit further comprises a bias circuit network for defining the dc bias current through the input differential amplifier stage and a delay circuit coupled between the bias circuit network and a power source voltage supply point.

Abstract: A Bode equalizer which has as one active element thereof a high-gain, differential-input amplifier and which has as a second active element a variable negative resistance, the equalizer circuit being controlled by a resistance arrangement which effectively comprises a series-connected, fixed resistor and the variable negative resistance.

Abstract: A millimeter wave amplifier having broadband characteristics in which a G diode or other two terminal negative resistance device having an integral heat sink is center mounted in a reduced height waveguide. The heat sink is attached to a mechanism for selectively adjusting its penetration into the waveguide cavity. The introduction of the heat sink into the waveguide cavity creates a discontinuity to the propagation of energy which causes localized waveguide modes other than the dominant mode to exist. The adjustable position of the heat sink allows the reactance due to the introduction of these modes to be variable, proper adjustment resulting in the cancellation of the parasitic reactances inherent in the packaged negative resistance device.

Abstract: A transistor amplifier including a bipolar transistor supplied with an input signal and a field effect transistor which is directly connected to an output electrode of the bipolar transistor to amplify a signal applied thereto. The transistor amplifier has a protective circuit which senses the load impedance and actuates a protective means across an input terminal of the transistor amplifier when the sensed load impedance is lower than a predetermined value. Accordingly, the transistor amplifier is protected against overload conditions.

Abstract: A transistor power amplifier for transmitting systems, particularly high frequency systems, has two parallel connected signal paths each of which is fed with the input signal. In a first of the signal paths, a 6 dB attenuator connects the input to the input of an amplifier and a fraction of the output of the amplifier is connected to one input of a correction amplifier, constructed as a differential amplifier. In the other signal path a delay member which simulates the delay of the first amplifier connects the circuit input to another input of the correction amplifier. The correction amplifier therefore is provided with a fraction of a delayed amplified signal which is subjected to error and includes an error component and with the delayed original input signal and emits a control signal for a second amplifier in which the error component produced in the first amplifier is contained in a double and inverted magnitude.

Abstract: A differential amplifier suited for use in operational amplifiers employing both FET's and junction transistors has a superior gain-bandwidth product for given input offset specification. Source-coupled FET's accept input signals at their gate electrodes. Each FET is included in a composite transistor device together with a direct coupled, inverting, current amplifier having an input terminal to which the drain electrode of the FET is coupled and having an output terminal coupled to the source electrode of the FET.

Abstract: A pulse width modulation circuit which comprises a mixer for combining an input audio signal with a feedback signal and for developing a difference signal to feed to an integration circuit. The integration circuit is coupled to a pulse width modulator which has a sawtooth carrier input for modulating the input audio signal. The resulting pulse modulated signal is then fed to a pulse amplifier and a low-pass filter and finally to a load. The output of the low-pass filter is coupled back to the mixer.

Abstract: A bias circuit for a large pulse-width, broad-bandwidth radio-frequency avalanche device comprising a power supply coupled to the device through a bias line. The bias circuit includes a resistive network shunted across the bias line and ground to dampen spurious submicrowave oscillations.

Abstract: An amplifier comprises a power amplifying circuit including FET's and operable when supplied with a first power source and a drive circuit operable when supplied with a second power source for driving the power amplifying circuit and including a bias circuit for providing bias voltages for the FET's. Upon turning on the power switch, the first power source builds up quickly while the second power source builds up with some time delay. Switch-over circuits connect the power lines of the drive circuit to the first power source initially and to the second power source after the build-up of the latter, thereby starting the supply of the bias voltages to the FET's at the build up of the first power source to prevent an excessively large current or rush current from flowing through the FET's, thus avoiding the breakage or characteristic deterioration of the FET's.

Abstract: In a color cathode ray tube including an electron gun means for projecting three electron beams in an in-line arrangement, there is provided deflection defocus correcting means which are disposed adjacent the side electron beams for neutralizing the deflection defocus of the side beam caused by the non-uniformity of the deflection fields.

Abstract: A device for protecting an audio amplifier against overload or short circuit. The device includes an output amplifier comprising a plurality of branches having output transistors, a preamplifier to control the output amplifier, and means for limiting the current through the transistors at an allowable value. The device further includes means which, when the current through the output transistors exceeds this value, limit this current at this value, and means which, in the presence of such an unallowably high current in one of the branches, immediately disconnect the output amplifier irrespective of the fact that this current occurs in the one or in the other branch.

Abstract: Current mirror amplifiers, which exhibit greater current attenuation (or gain) than prior art current mirror amplifiers taking up the same area on a monolithic integrated circuit die, are described in which the base-emitter junctions of the mirroring transistors are dissimilar in profile.

Abstract: A mask type color picture tube has a mask electrode attached to a peripheral frame having an L-shaped cross-section which is suspended within the tube adjacent a screen of the tube. The mask includes a curved apertured portion. At least an outer area of the apertured portion lies in a curved plane that passes substantially behind a part of the frame closest to the screen.

Abstract: An improved low-noise microwave amplifier comprises a circuit arrangement coupled in parallel with a GaAs FET amplifying stage for reducing transmission loss in case of dc power failure or amplifying stage failures. The circuit arrangement comprises two microwave circulators and a microwave isolator connected therebetween.

Abstract: A Class AB linear power amplifier circuit is connected in a balanced bridge configuration for increasing the fidelity and power output from stereophonic sound systems, such as used primarily in automotive vehicles, the circuitry consisting of a series of NPN transistors and PNP transistors, with bias for the transistors provided by a power source, a series of resistors and thermistors, an optional input overload protection circuit, with the transistors further being matched and balanced so as to effectively double or quadruple output power as would be available from a single ended configuration, so that the amplifier circuitry operates in a Class A mode to eliminate any crossover distortion.