Itt Industries, Inc.

Deutsche Itt Industries Gmbh

Bernd Novotny

Herbert Elmis

Hermannus Schat

Dietmar Ehrhardt

Otmar Kappeler

Laurin C Freyberger

Harald Schilling

Gerhard Gunter

Gerhard G Gassmann

A monolithic integrated wideband power amplifier circuit has a push-pull output stage, a driver stage, a difference stage which receives an input voltage signal and provides a difference signal, and the improvement of an operating point setter which receives the difference signal and controls the operating point of the circuit through a settable resistor. The setting of the operating point is independent of the gain of the output stage, and both are independent of temperature. The bipolar NPN transistors of the push-pull output stage consists of parallel-connected subtransistors which are arranged in the integrated circuit layout according to their characteristics and specific use, so as to minimize parasitic capacitances and resistances and to keep the upper cutoff frequency as high as possible.

Monolithic integrated wideband power amplifier

The frequency conversion of an RF signal is performed by the 'third method' using a suitable frequency reversal which makes the frequencies of the picture carrier, the chrominance subcarrier, and at least one sound carrier appear transformed into the baseband, such that the frequencies of the transformed picture carrier and the transformed chrominance subcarrier coincide. Unavoidable differences in the signal paths of the frequency reversal result in a spurious signal which produces a temporally/locally varying moire on the screen. By means of a frequency offset, this spurious signal is transformed into a frequency range which is not found annoying by the observer, so that the moire becomes invisible. This frequency range is preferably the exact center region between two spectral lines of the horizontal frequency of the composite color signal in the baseband.

Frequency conversion of an RF signal transmitted for color-television

A television sound receiving circuit for at least one sound channel contained in an RF signal converts the transmitted or already down-converted television signal as a composite signal to the baseband in a single-sideband demodulator circuit using the 'phasing method', separates the first sound channel, corresponding to a lower sideband, and the second sound channel, corresponding to an upper sideband, and produces first and second sound signals at the desired frequency by subsequent frequency demodulation. Also shown are the interfaces for possible digitization and an advantageous use of the interfaces in which picture and sound signals are digitized together. The data can be combined into a single data stream which can be transferred over a bus system and is separable into the individual components if required.

Television sound receiving circuit for at least one sound channel

A frequency/phase locked loop for providing signals which are frequency and phase locked to signals at a reference frequency from a reference oscillator which is determinative of the frequency stability includes a frequency-controlled generator of a lower frequency stability. The frequency controlled generator is responsive to control signals for switching between first and second frequencies which are substantially higher than the reference frequency. The second frequency is approximately one to ten percent higher than the first frequency. The frequency divider coupled to the frequency generator provides an output signal at the same frequency as the reference oscillator. A digital phase comparator compares the outputs of the frequency divider with the reference signals. A digital integrating stage coupled to the comparator provides the control signals such that during a first portion of a period of the reference signals the first frequency is selected and during a second portion of the period the second frequency is selected.

Digital frequency/phase locked loop

The interface circuit contains a single operational amplifier (OR, OG, OB) per chrominance channel, with a resistance network (WR, WG, WB) for white-level adjustment connected between the inverting input and the output of this amplifier. The output resistances of the matrix output amplifiers (MR, MG, MB) must be low, and a low-value resistor (RR, RG, RB) is connected between the output of each output amplifier and the noninverting input of each operational amplifier (OR, OG, OB). Video-signal, brightness-, blanking, and external-signal-control currents (ISR, ISG, ISB; IHR, IHG, IHB; IBR, IBG, IBB; IER, IEG, IEB) are applied to the non-inverting input of the respective operational amplifier. The control currents permit the white-level adjustment and the blanking-voltage adjustment to be made independently of each other and eliminate any interaction between brightness adjustment, blanking, and external-signal gating. Compared with prior art arrangements, a simpler circuit is obtained.

Integrated interface circuit between the RGB matrix and the video output

Switch-mode power supply generating a variable pulse-width modulating signal by digital control techniques synchronized with the horizontal line rate of the receiver. Logic circuits operating against fixed references provide overload and short-circuit protection by rapidly decreasing the variable pulse-width signal duration during various fault conditions.

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Gundelfingen, Germany

Bernd Novotny