GT4122

52025DOC

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Technical content

-VS +V S COMP C OS1 C OS2 VREF VC GND OUT BOS2 -IN B +IN B BOS1 AOS2 -IN A +IN A AOS1 R EXT 1110 PIN 1 TOP VIEW Document No. 520 - 25 - 4 DATA SHEET GT4122 Video Multiplier GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. (905) 632-2996 fax: (905) 632-5946 Japan Branch: A-302, Miyamae Village, 2-10-42 Miyamae, Suginami-ku, Tokyo 168, Japan tel. (03) 3334-7700 fax: (03) 3247-8839

DESCRIPTION

The GT4122 multiplier is a monolithic dual-channel, broadcast quality video mixer. Featuring two wideband video inputs and a single control input, the GT4122 achieves high quality video mixing of the two video input signals to a single output by implementing the function: V OUT = VA • VC + VB (1 - V C) where V C is the control input voltage, which may be varied continuously over the control range and V A and VB are the video input signals. The GT4122 operates with power supply voltages of ± 10 volts and typically draws 24 mA of current. The GT4122 is available in a 20 pin DIP and 20 pin SOIC packaging. An Application Note entitled ‘Using the GT4122 and GT4124 Video Mixer ICs’ (Gennum Document 520-44) is available from Gennum Corporation.

FEATURES

• broadcast quality video multiplier
• 30 MHz at -1.0 dB video and control channel bandwidth
• one external frequency compensation adjustment
• ultra low differential gain and differential phase, (typically 0.01 % and 0.01 deg.)
• external DC offset and span trims
• 20 pin PDIP and SOIC packaging

APPLICATIONS

• Production switcher video mixers
• Linear Keyers Part No. Package Type Temperature GT4122 - CDF 20 PDIP 0 ° to 70°C GT4122 - CKF 20 SOIC 0 ° to 70°C

ORDERING INFORMATION

20 PIN DIP / SOIC

• VS GND A OS2 +IN A - IN A B OS2 - IN B VCA=0.5 + VK +IN B +VS B OS1 A OS1 BIAS AMP 3 S 2 COMP OUT VNOM AMP 1 AMP 2 XA VCB=0.5 - VK XB AMP 4 A K 0.5V + VK - VK VNOM Device Function: VOUT = VINA • [VNOM + AK (VC - VREF)] + VINB • [VNOM - AK (VC - VREF)] FUNCTIONAL BLOCK DIAGRAM 1- V S negative supply voltage 2+ V S positive supply voltage

3 COMPoutput freq'y comp'n R-C

OS1 control input offset adjust 5C OS2 control input offset adjust

6 S1 span adjust

REF 0.5volt reference input

8 S2 span adjust

10 GND ground

EXT current setting resistor

12 A OS1 A black level adjust (OFFSET)

13 +IN A A video + input signal 14 -IN A A video - signal input 15 A OS2 A black level adjust (OFFSET)

16 B OS1 B black level adjust (OFFSET)

17 +IN B B video + signal input 18 -IN B B video - signal input 19 B OS2 B black level adjust (OFFSET)

20 OUT multiplier output

Revision Date: January 1994.

Supply Voltage (VS) ± 13.5 V Operating Temperature Range 0 ° C ≤ TA ≤ 70° C Storage Temperature Range -65 ° C ≤ TS ≤ 150° C Lead Temperature (Soldering, 10 Sec) 260 ° C Video Input Voltage (VA,VB) to ground ± 5 V Control Input Voltage (VC) to ground ± 5 V Video Input Differential Voltage (VA - VB) ± 5 V Control Input Differential Voltage (VC -VREF) ± 5 V ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage ± VS Operating Range ± 9 ± 10 ± 12 volts + Supply Current I+ R EXT = 1 k Ω -2 4 2 8 m A - Supply Current I- R EXT = 1 k Ω -1 8 2 0 m A Bandwidth BW at ± 0.1 dB V SIG =150 mVp-p 25 30 - MHz Frequency Response DC - 10 MHz - ± 0.05 - dB Differential Gain ∂gV IN = 40 IRE at 3.58 MHz - 0.01 0.03 % Differential Phase ∂pV IN = 40 IRE at 3.58 MHz - 0.01 0.03 degrees Signal to Noise S/N V SIG = 1 volt, BW = 5 MHz 64 70 - dB Gain - open loop A OL 100 kHz (ß = 0%) 54 60 66 dB Gain - closed loop A CL 100 kHz (ß = 100%) -0.01 -0.005 - dB Delay td SIG -- 1 0 n s Off Isolation & Crosstalk V A or B /VO ƒSIG = 5 MHz (see note 1) 80 85 - dB VC/VA or B ƒSIG = 5 MHz (see note 2) 90 95 - dB Bandwidth BW at ± 0.1 dB V SIG =150 mVp-p 25 30 - MHz Delay t d CONT -- 1 0 n s Linearity -1 - % Control Breakthrough V CONT = 0-1 V ƒ = 1-10 MHz - -55 -50 dB Crossfade Balance V CONT = 0-1 V ƒ = 3.58 MHz - 3 5 mVpp Control Range V CONT 0- + 5 V NOTE: 1 V A or B =1 Vp-p output taken from OUTPUT

2 VCONT =1 Vp-p output taken from V A or VB

(+VS = -V S =10V, 0 °C ≤ TA ≤ 70°C unless otherwise shown) SIGNAL CHANNEL POWER SUPPLIES CONTROL CHANNEL

Referring to the block diagram, the input signals are applied to conventional differential amplifiers (AMP1 and AMP2). Each amplifier has provisions for individually adjusting the DC offset (OFFSET). Following each input amplifier, the signals are applied to linear multiplier circuits (XA and XB) whose outputs are the product of the incoming signals and controlling voltages (V CA) or (VCB). The controlling voltage V CA is the sum of a nominal 0.5V source (VNOM) and a variable source VK while VCB is made up of the sum of the nominal voltage VNOM and -VK. VK and -V K are themselves proportional to the difference between an externally applied reference voltage (V REF) and an externally applied CONTROL voltage (VC). The voltages VK and -VK are produced by a differential amplifier (AMP3) whose gain is AK. This gain can be altered by two external resistors, REXT and RSPAN according to the following formula: Note that REXT is connected between the REXT pin and ground and RSPAN is connected between the pins S1 and S2. Each of the voltages (+V K and -V K) is applied to summing circuits ( Σ2 and Σ3) whose second inputs are DC voltage sources that can also be slightly varied. The nominal value of these voltage sources is 0.5 volts. When they are exactly 0.5V and when V C = VREF, the gain of each signal channel of the mixer is 0.5 (50%). By connecting the ends of an external potentiometer (CONTROL OFFSET) between the offset pins COS1 and COS2, the voltage sources can be altered differentially. If a second potentiometer (50% GAIN) is connected between the wiper of the CONTROL OFFSET potentiometer and the supply voltage, the voltage sources can be varied in a common mode fashion. In this way not only can the control range of the mixer be varied but also the point at which 50% of each input signal appears at the output. The outputs from the multiplier circuits (XA and XB) are then applied to a summing circuit ( Σ1) whose output feeds a wideband amplifier (AMP4) and presents the mixed signals to the outside world. Although there are two separate differential inputs, the usual operational amplifier gain-setting methods can be applied to determine the closed loop gain of the mixer. Usually the mixer will be configured for unity gain by connecting both inverting inputs (-IN A , -IN B) to the common output (OUT). In this case, the general transfer function is: V O = V A •[VNOM + A K•(VC - V REF)] + V B•[VNOM - A K•(VC - VREF)] (Unity gain configuration) Where VA and VB are the input analog signals applied to +IN A and +IN B respectively, and VC is the CONTROL voltage. Note that VNOM ranges between 0.45V < VNOM < 0.55. DETAILED DESCRIPTION 0.85 • REXT RSPAN REXT COS1 VREF COS2 VC - VS GND A OS2 +IN A - IN A B OS2 - IN B VCA=0.5 + VK +IN B +VS B OS1 A OS1 BIAS AMP 3 S 2 COMP OUT VNOM AMP 1 AMP 2 XA VCB=0.5 - VK XB AMP 4 A K 0.5V + VK - VK VNOM Device Function: VOUT = VINA • [VNOM + AK (VC - VREF)] + VINB • [VNOM - AK (VC - VREF)] The GT4122 is a broadcast quality monolithic inte- grated circuit specifically designed to linearly mix two video signals under the control of a third signal. FUNCTIONAL BLOCK DIAGRAM

For normal video mixer operation, the control range (SPAN) is usually 0 to 1V and will occur when A K=1, VREF= 0.5V and VNOM=0.5 volts. A change in VC from 0 to 1V will then produce an effect such that the output signal contains 100% of Channel B when V C is 0V and 100% of Channel A when VC is 1 volt. For the above conditions, the general unity gain transfer function reduces to: V O = VA•VC + VB•(1-VC) Since the operation of the mixer is limited to two quadrants, no signal inversions occur if the control voltage exceeds the range zero to one volt in either direction. The topology is designed so that once the control voltage reaches either end of its range, the channel which is ON remains fully ON and the OFF channel remains fully OFF. 0.1 or LINK GT4122 CONTROL OFFSET RV2 100 0.1 COUT -5V C6 0.1 ROUT 10k or OPEN +5V B VIDEO INPUT CONTROL INPUT 6.2V RV1 200 C2 0.1 560 (0.5V) 5.6k 50% GAIN B BLACK LEVEL ADJUST A BLACK LEVEL ADJUST if required RV4 500 RV5 500 +10V -10V -VS GND COMP COS1 OUT B OS2 +IN B -IN B A OS2 -IN A VREF +IN A AOS1 -10V C1 0.1 5 - 25pF CCOMP RV6 1k VREF ADJUST RV3 SPAN ADJUST 0.1 +VS COS2 VC REXT B OS1 C7 0.1 A VIDEO INPUT if required if required IC2 CLC110 VIDEO OUT NOTE: C5 is used when the CONTROL VOLTAGE (VC) is derived from a power supply. All resistors in ohms, all capacitors in µF unless otherwise stated. Fig. 1 Test Circuit

Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. © Copyright April 1991 Gennum Corporation. All rights reserved. Printed in Canada. DOCUMENT IDENTIFICATION PRODUCT PROPOSAL This data has been compiled for market investigation purposes only, and does not constitute an offer for sale. ADVANCE INFORMATION NOTE This product is in development phase and specifications are subject to change without notice. Gennum reserves the right to remove the product at any time. Listing the product does not constitute an offer for sale. PRELIMINARY DATA SHEET The product is in a preproduction phase and specifications are subject to change without notice. DATA SHEET The product is in production. Gennum reserves the right to make changes at any time to improve reliability, function or design, in order to provide the best product possible. CAUTION ELECTROSTATIC SENSITIVE DEVICES DO NOT OPEN PACKAGES OR HANDLE EXCEPT AT A STATIC-FREE WORKSTATION GAIN (dB) FREQUENCY (MHz) -20 -30 -40 -50 -60 -70 -80 -90 -100 1 1001 10 100 VIN = 1 Vp-p CH-A CH-B GAIN (dB) 1 60 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 11 0 6 0 FREQUENCY (MHz) CH-B VIN = 150 mVp-p RCOMP = 560 Ω CCOMP = 18 pF CH-A Fig. 3 Crosstalk vs FrequencyFig. 2 Frequency Response dg (%) / dp (deg) FREQUENCY (MHz) 0.03 0.02 0.01 0.00 -0.01 -0.02 -0.03 13 5 1 0 dg dp Fig. 4 Differential Gain & Phase vs Frequency GAIN (dB) 1 10 -20 -30 -40 -50 -60 -70 -80 -90 -100 13 5 1 0 VC = 1Vp-p+0.5 VDC REF = 1Vp-p (0dB) FREQUENCY (MHz) Fig. 5 Crossfade Balance vs Frequency TYPICAL PERFORMANCE CURVES FOR GT4122 (Unless otherwise shown, VS = ± 10 V, RL = 10 kΩ )