US 5,402,180 AGranted

RGB encoder for producing a composite video signal for NTSC and PAL systems

AssigneeSamsung Electronics Co., Ltd.

InventorSoon-gil Jung

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Abstract

An RGB encoder includes a Y-matrix processor, a chrominance signal processor, a bandpass filter, a delay element, an OTA (operational transconductance amplifier) control signal generator and a mixer. The OTA bandpass filter has a plurality of operational transconductance amplifiers for bandpass-filtering the chrominance signal, wherein the passband is varied according to the transconductance of the operational transconductance amplifiers included therein. The OTA delay element has a plurality of operational transconductance amplifiers for receiving and delaying the luminance signal, wherein the delay time is varied according to the transconductance of the operational transconductance amplifiers included therein. The OTA control signal generator generates first and second control signals in accordance with an NTSC/PAL select signal. The first control signal controls the transconductance of the operational transconductance amplifiers included in the OTA bandpass filter and the second control signal controls the transconductance of the operational transconductance amplifiers included in the OTA delay element. The mixer mixes the outputs of the bandpass filter and delay element, in order to produce a composite video signal. The RGB encoder has lower manufacturing costs and reduced power consumption.

Claims10

Dependent claims

An RGB encoder which selectively encodes an RGB video signal into an NTSC system composite video signal or a PAL system composite video signal in accordance with an NTSC/PAL select signal, using a composite sync pulse input containing composite sync pulses, the encoder comprising:

means for processing said RGB video signal and said composite sync pulse input to produce a luminance signal incorporated into the composite sync pulses;
means for processing said RGB video signal to produce a chrominance signal;
an operational transconductance amplifier (OTA) bandpass filter having a plurality of operational transconductance amplifiers, for bandpass-filtering said chrominance signal in accordance with a passband which is varied by varying the transconductance of the operational transconductance amplifiers included therein in response to a first control signal;
an OTA delay element having a plurality of operational transconductance amplifiers, for receiving said luminance signal and delaying said received luminance signal to produce a delayed luminance signal having a delay time which is varied by varying the transconductance of the operational transconductance amplifiers included therein in response to a second control signal;
a control signal generator for generating said first control signal and said second control signal in accordance with the NTSC/PAL select signal, wherein said first control signal controls the transconductance of the operational transconductance amplifiers included in said OTA bandpass filter, and said second control signal controls the transconductance of the operational transconductance amplifiers included in said OTA delay element;
and
means for mixing the output of said OTA bandpass filter and the output of said OTA delay element to produce a composite video signal.

4 more elements

Dependencies are inferred from the claim text.