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| GT4123, GT4123A Two Channel Video Multipliers DATA SHEET FEATURES * two-quadrant video multiplication * 20 MHz 0.1 dB video & control channel bandwidth * one external frequency compensation adjustment * ultra low differential gain & differential phase * convenient 8 pin package APPLICATIONS * Multimedia Graphics Overlay * Production switchers * Linear Keyers PIN CONNECTIONS TOP VIEW OUTPUT FREQ. COMP CONTROL GROUND 4 5 PIN 1 8 V DESCRIPTION The GT4123 and GT4123A are monolithic dual-channel video multipliers for use in a wide range of applications including broadcast and multimedia. Featuring two wideband video inputs and a single control input, they achieve high quality video mixing of the two video input signals to a single output by implementing the function: VO = [ ( VC * VA ) + (1 - VC ) * VB ] where VC is the control input voltage, which may be varied continuously over the range 0 to 1V with respect to the ground pin, and VA and V B are the video input signals. The GT4123 operates with typical power supply voltages of 10 volts and draws 15 mA of current. The GT4123A typically operates from +12 and -5 volt supplies. Both are available in 8 pin PDIP and 8 pin SOIC. An Application Note entitled "Using the GT4123 and GT4123A Video MIxer ICs" (Document No. 520 - 61) is available from Gennum Corporation. cc VIDEO IN B V EE VIDEO IN A MULTIPLIER CORE VIDEO IN A FREQ COMP 8 PIN DIP VIDEO IN B OUTPUT ORDERING INFORMATION Part Number GT4123 - CDA GT4123 - CKA GT4123ACDA GT4123ACKA Package Type 8 pin PDIP 8 pin SOIC 8 pin PDIP 8 pin SOIC Temperature Range 0o 0o 0o 0o to 70o C to 70o C to 70o C to 70o C CONTROL VREF (0.5V) (INTERNAL) FUNCTIONAL BLOCK DIAGRAM CAUTION ELECTROSTATIC SENSITIVE DEVICES DO NOT OPEN PACKAGES OR HANDLE EXCEPT AT A STATIC-FREE WORKSTATION Revision Date: January 1994. Document No. 520 - 38 - 3 GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 Japan Branch: A-302, M i yamae Vi l l age, 2-10-42 M i yamae, Suginami-ku Tokyo 168, Japan tel. (905) 632-2996 fax: (905) 632-5946 tel. (03) 3334-7700 fax (03) 3247-8839 ABSOLUTE MAXIMUM RATINGS PARAMETER Supply Voltage (VS) Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 Sec) Video Input Voltage (VA,VB) to ground Control Input Voltage (VC) to ground Video Input Differential Voltage (VA - VB) VALUE 13.5 V 0 C TA 70 C -65 C TS 150 C 260 C 5 V 5 V 5 V ELECTRICAL CHARACTERISTICS GT4123 PARAMETER Supply Voltage POWER SUPPLIES + Supply Current - Supply Current Common Mode Input Signal Bandwidth Bandwidth Frequency Response Differential Gain Differential Phase SIGNAL CHANNEL Signal to Noise Gain Delay Off Isolation & Crosstalk g p S/N AVL SYMBOL VS I+ IVIN CM BW0.1 BW3 V S = 10V, T A = 0C to 70C, RL =10k unless otherwise shown. CONDITIONS Operating Range MIN 9 - TYP 10 15 13 25 80 0.05 0.01 0.01 70 -0.005 4 75 85 2.0 2.0 25 80 4 1 5 - MAX 12 19.5 17.0 5 0.05 0.05 10 0.1 10 -35 10 +1 UNITS V mA mA V MHz MHz dB % degrees dB dB ns dB dB k pF pF MHz MHz ns % dB mVp-p V at 0.1 dB VIN = 150 mVp-p at -3 dB VIN = 1 Vp-p DC -10 MHz VIN = 40 IRE at 3.58 MHz VIN = 40 IRE at 3.58 MHz VSIG = 1 V, BW = 5 MHz 100 kHz ( = 100%) 20 64 -0.02 - td SIG VA or B VO VC VA or B RIN CIN ROUT COUT BW0.1 BW3 tD CONT SIG = 5 MHz (see note 1) SIG = 5 MHz (see note 2) =1 MHz 70 80 150 - Input Resistance Input Capacitance Output Resistance Output Capacitance Bandwidth CONTROL CHANNEL Bandwidth Delay Linearity Control Breakthrough Crossfade Balance Control Range NOTE: =1 MHz (see Figure 9) - at 0.1 dB VIN = 150 mVp-p at -3 dB VIN = 1 Vp-p 10% to 90% range VC = 0 to 1 V C =1 to 10 MHz VC = 0 to 1 V C = 3.58 MHz 20 0 VC (see Figure 10) 1. V A or B = +1 Vp-p output taken from OUTPUT 2 . VC = +1 Vp-p output taken from VA or V B 520 - 38 - 3 2 ELECTRICAL CHARACTERISTICS GT4123A PARAMETER Supply Voltage POWER SUPPLIES + Supply Current - Supply Current Common Mode Input Signal Bandwidth Bandwidth Frequency Response Differential Gain SIGNAL CHANNEL Differential Phase Signal to Noise Gain Delay Off Isolation & Crosstalk g p S/N AVL SYMBOL VS I+ IVIN CM BW 0.1 BW 3 V S = 12V, -5V, TA = 0C to 70C, RL=10k unless otherwise shown. CONDITIONS Operating Range MIN +9 -3 - TYP +12 -5 15 13 25 80 0.05 0.02 0.02 70 -0.005 4 75 85 2.0 2.0 25 80 4 1 5 - MAX 12 UNITS V 19.5 17.0 5 0.05 0.05 10 0.1 10 -35 10 +1 mA mA V MHz MHz dB % degrees dB dB ns dB dB k pF pF MHz MHz ns % dB mVp-p V at 0.1 dB V IN = 150 mVp-p at -3 dB V IN = 1 Vp-p DC -10 MHz VIN = 40 IRE at 3.58 MHz VIN = 40 IRE at 3.58 MHz VSIG = 1 V, BW = 5 MHz 100 kHz ( = 100%) 20 64 -0.02 - t d SIG VA or B VO VC VA or B RIN CIN ROUT COUT BW 0.1 BW 3 t D CONT SIG = 5 MHz (see note 1) SIG = 5 MHz (see note 2) =1MHz 70 80 150 - Input Resistance Input Capacitance Output Resistance Output Capacitance Bandwidth Bandwidth CONTROL CHANNEL Delay Linearity Control Breakthrough Crossfade Balance Control Range NOTE: =1MHz (see Figure 9) - at 0.1 dB V IN = 150 mVp-p at -3 dB V IN = 1 Vp-p 10% to 90% range V C = 0 to 1 V C =1 to 10 MHz VC = 0 to 1 V C = 3.58 MHz 20 0 VC (see Figure 10) 1. V A or B = +1 Vp-p output taken from OUTPUT 2 . VC = + 1 Vp-p output taken from V A or V B 3 520 - 38 - 3 DETAILED DESCRIPTION The GT4123 and GT4123A are the first dedicated single device, two input video mixer ICs available to the professional video and multimedia markets. The internal topology of the devices is shown in Figure 1. When VC is less than 0.5 volts, VCA reduces and VCB increases in proportion so that less of the Channel A signal and more of the Channel B signal is transferred. Similarly, when VC is greater than 0.5 volts, the opposite occurs. The SPAN or control range is internally set so that a CONTROL voltage of 0 volts completely cuts off Channel A and fully turns on Channel B. Similarly, a CONTROL voltage of 1 volt will fully turn on Channel A and completely turn Channel B off. XA VCA + 1 + AMP D OUT COMP IN A AMP A + Figure 10 shows the CONTROL transfer characteristics of the GT4123 and GT4123A. There is a small `dead band' at either extreme of the CONTROL input. The amount of `dead band' is about 100 mV and is shown in Figure 10. The CONTROL input can be preceded by an operational amplifier so biased as to overcome this `dead band' as well as level shift the control signal so that other than 0 to 1 volt ranges can be used. The bandwidth of the CONTROL input is sufficient to allow very fast keying and is in the order of 20 MHz at -0.1 dB. The linear portion of the transfer characteristic has a linearity of 1% or better. The outputs from the multipliers are applied to an analog summing circuit (1) whose output feeds a wideband amplifier (Amp D) and presents the mixed signals to the outside world. The inverting inputs of each input amplifier are directly connected to the output. In this manner the closed loop gain is nearly unity providing wideband, stable operation. Because the devices have only 8 pins and require virtually no external parts in order to function, they lend themselves to high density, multi-functional PC board layouts. Several devices can be used in parallel applications such as R-G-B mixers and four-layer keyers where close control law tracking is essential. The only difference between the GT4123 and the GT4123A is the fact that the latter device can operate with non-equal power supplies. The negative supply can be as low as -3 volts unlike the GT4123 which can only operate down to 9 volt supplies. IN B + AMP B XB VCB VCB = 0.5 - (VC - 0.5) VCA = 0.5 + (VC - 0.5) CONTROL (VC) AMP C + 2 + 3 + + + 0.5V REF Fig. 1 Functional Block Diagram of the GT4123 and GT4123A Each input signal is applied to a conventional differential amplifier (AMP A and AMP B). From the amplifiers, the signals are applied to analog multiplier circuits (XA and XB) whose outputs are the product of the input signals and internally generated controlling voltages VCA and VCB. These voltages are derived from a unity gain differential amplifier (AMP C) whose outputs (true and invert) are the difference between an externally applied CONTROL voltage (VC) and an internal 0.5 volt reference voltage. In addition, the internal DC offset of 0.5 volts is applied to the controlling voltage summing circuits 2 and 3. Therefore, VCA = 0.5V + (VC - 0.5V) and VCB = 0.5V - (VC - 0.5V) When the CONTROL input (VC ) equals 0.5 volts, V CA and VCB = 0.5 volts and exactly 50% of each input signal passes to the output of the multiplier stages. 520 - 38 - 3 4 GT4123 / GT4123A TEST CIRCUITS +10V 0.1 +5V 0.1 1 TO NETWORK ANALYSER 7 8 4 75 DUT 5 1 4 CLC110 0.1 5 10k 8 6 3 75 0.1 -5V 0.1 FROM NETWORK ANALYSER -10V All resistors in ohms, all capacitors in F unlesss otherwise stated. VSIG = 1VP-P + 0.5V BIAS (100 kHz to 10 MHz) Fig. 2 Crossfade Balance +10V 0.1 7 8 4 5 - 30pF 2 +5V FROM NETWORK ANALYSER 680 75 0.1 1 TO NETWORK ANALYSER DUT 5 6 3 1 4 CLC110 0.1 5 10k 8 75 0.1 -5V 0.1 -10V +1V B A All resistors in ohms, all capacitors in F unlesss otherwise stated. Fig. 3 Frequency Response, Crosstalk & Differential Gain & Phase (+12V) +10V (-5V) -10V 0.1 0.1 8 6 GT4123 (GT4123A) VA 75 5 7 4 3 2 1 6dB AMPLIFIER VIDEO OUT 75 All resistors in ohms, all capacitors in F unlesss otherwise stated. VB 680 75 5-30 pF VC Fig. 4 Typical Application Circuit 5 520 - 38 - 3 TYPICAL PERFORMANCE CURVES FOR GT4123 / GT4123A 0.5 0.4 0.3 0.2 0.1 -40 -50 -20 CH-A -30 VIN=1Vp-p CH-B dB -0.1 -0.2 -0.3 -0.4 -0.5 1 CH-A dB 0.0 -60 -70 VIN = 150mVp-p RCOMP = 680 CCOMP = 18pF 1 10 100 CH-B -80 -90 -100 1 1 100 100 10 100 FREQUENCY (MHz) FREQUENCY (MHz) Fig. 5 Frequency Response Fig. 6 Crosstalk vs Frequency 0.03 -30 0.02 VC = 1Vp-p+0.5VDC -35 REF = 1Vp-p (0dB) 0.01 -40 dg / dp dg dB dp -0.02 1 10 0.00 -45 -0.01 -50 -55 -0.03 1 3 5 10 -60 0.1 1 10 FREQUENCY (MHz) FREQUENCY (MHz) Fig. 7 Differential Gain & Phase vs Frequency Fig. 8 Crossfade Balance vs Frequency 1.0 0.9 0.8 0.7 CH-B 100 CH-A RESISTANCE () 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.01 01 GAIN (%) 0.1 1.0 10 50 0 10 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 FREQUENCY (MHz) CONTROL VOLTAGE (VC ) Fig. 9 Output Resistance vs Frequency Fig. 10 Control Characteristics 520 - 38 - 3 6 |
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