Itt Industries, Inc.

Wolfgang Sauer

Laurin C Freyberger

Friedrich Schmidtpott

Wolfgang Hoehn

Hermanus Schat

To increase the gain and, consequently, to increase the voltage amplitude appearing at the crystal of a crystal oscillator a conventional circuit including a first differential amplifier in the amplifier section and two further differential amplifiers in the phase shifting section is modified to include a fourth differential amplifier in the amplifier section. The fourth amplifier carries an additional current to flow in the two differential amplifiers causing an additional current to flow and across the operating resistance of the two differential amplifiers an additional voltage drop being fed to the crystal via an emitter follower.

Monolithic integrated transistor HF crystal oscillator circuit

This integrated circuit contains the horizontal sweep generator (HO), the amplitude filter (AS), the sync-signal separating circuit (SA) and the frequency/phase comparator (FP). For the purpose of suppressing noise pulses which are caused via the operating voltage during the upper and the lower inversion point of the horizontal sweep generator (HO) which contains a single capacitor (C) and a first threshold stage circuit (SS1) with two fixed thresholds, there are provided a second and a third threshold stage circuit (SS2, SS3), to the inputs of which the sawtooth signal is applied, and with the thresholds thereof, approximately 2 .mu.s prior to reaching the upper or the lower peak value of the sawtooth signal, are being passed through thereby. The output signal of the second threshold circuit (SS2) and the output signal of the third threshold stage circuit (SS3) which is applied via the pulse shaper circuit (IF), are superimposed linearly and, via the stopper circuit (blocking stage) (SP) serve to control the application of the composite video signal (BAS) to the amplitude filter (AS), or else they are applied to a clamping circuit which serves to apply the operating points of the amplitude filter (AS) and/or of the sync-signal separating circuit (SA) to such a potential that these two stages, for the time duration of these output pulses, are prevented from operating.

Integrated circuit for color television receivers

An improved kit of two integrated circuits having a phase-locked loop clock oscillator for use in a color television receiver utilizing digital signal processing is described. The voltage controlled oscillator and the phase discriminator of the phase-locked loop are each located in a different one of the two integrated circuits. The control signals for the voltage controlled oscillator are transferred into it via a two-wire digital bus. External discrete components are eliminated.

Integrated circuit kit with a phase-locked loop for color television

A monolithic integrated circuit for an RC oscillator includes a differential amplifier acting as a switching stage for comparing a threshold voltage corresponding to the maximum oscillator voltage with the capacitor voltage of the RC circuit. An output of the differential amplifier is connected to the S input of an R-S flip-flop which is set when the capacitor voltage reaches the threshold voltage. A switching transistor has its collector and emitter connected across the capacitor and a base connected to the output of the R-S flip-flop for discharging the capacitor when the flip-flop is set. A second transistor has its base-emitter junction connected across the base-collector junction of the switching transistors so that when the switching transistor has discharged the capacitor to a point that only its collector-to-emitter saturation voltage dropped across it, the second transistor is turned on to provide a signal to the reset input of the flip-flop, thereby inhibiting the discharge of the capacitor and allowing the capacitor to recharge through a current source.

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Freiburg, Germany

Wolfgang Sauer