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GT4123B Two Channel Video Multiplier
DATA SHEET
FEATURES
DESCRIPTION The GT4123B is a monolithic dual-channel video multiplier for use in a wide range of applications including broadcast and multimedia. Featuring two wideband video inputs and a single control input, the GT4123B achieves broadcast quality mixing of 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 V to 1 V, and VA and V B are the video input signals. The GT4123B is a low power version of the GT4123 and GT4123A Video Multipliers which operates from 5 V supply voltages and typically draws only 15 mA of current.
two-quadrant video multiplication operation from 4.5 V to 13.2 V supply voltages 20 MHz 0.1 dB video & control channel bandwidth ultra low differential gain & differential phase convenient 8 pin package Pb-free and Green
APPLICATIONS * Multimedia Graphics Overlay * Production Switchers * Linear Keyers PIN CONNECTIONS GT4123B
FUNCTIONAL BLOCK DIAGRAM
VIDEO IN A
OUTPUT FREQ. COMP CONTROL GROUND
1 2 3 4
8 7 6 5
V
FREQ COMP MULTIPLIER CORE
cc
VIDEO IN B V
VIDEO IN B
EE
OUTPUT
VIDEO IN A
CONTROL
ORDERING INFORMATION
Part Number GT4123BCDA GT4123BCKA GT4123BCTA GT4123BCKAE3 Package Type 8 pin PDIP 8 pin SOIC 8 pin SOIC Tape 8 pin SOIC Temperature Range 0 to 70 C 0 to 70 C 0 to 70 C 0 to 70 C Pb-Free and Green No No No Yes
VREF (0.5V) (INTERNAL)
Revision date: July 2004
Document No. 521 - 20 - 02
GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. (905) 632-2996 fax: (905) 632-5946
Gennum Japan: Shinjuku Green Tower Building 27F 6-14-1, Nishi Shinjuku Shinjuku-ku, Tokyo 160-0023 Japan Tel: +81 (03) 3349-5501 Fax: +81 (03) 3349-5505
ABSOLUTE MAXIMUM RATINGS
PARAMETER Supply Voltage Operating Temperature Range Storage Temperature Range VALUE/UNITS 13.5 V 0C TA 70C
CAUTION
ELECTROSTATIC SENSITIVE DEVICES
DO NOT OPEN PACKAGES OR HANDLE EXCEPT AT A STATIC-FREE WORKSTATION
-65C TS 150C Lead Temperature (soldering, 10 seconds) 260C Video Input Voltage Control Input Voltage Video Input Differential Voltage 5 V 5 V 5 V
ELECTRICAL CHARACTERISTICS GT4123B
PARAMETER Supply Voltage POWER SUPPLIES + Supply Current - Supply Current Common Mode Input Signal SYMBOL VS I+ IV IN CM
VS = 5V, T A = 0C to 70C, RL=10k, C L=10pF unless otherwise shown.
CONDITIONS
MIN 4.5 -
TYP 5 15 15
MAX 13.2 19.5 19.5
UNITS V mA mA
Supply Voltage = 5 V Positve Excursion Limit Negative Excursion Limit 10 20 25 0.01 2.2 -3.5 0.02 V V MHz MHz %
Bandwidth
BW0.05 BW 0.1
0.05 dB, V IN= 150 mVp-p 0.1 dB, VIN= 150 mVp-p V IN = 40 IRE, 0V CM at 3.58 MHz and 4.43 MHz V IN = 40 IRE, 0V CM at 3.58 MHz and 4.43 MHz V SIG = 1 Vp-p, 100 kHz ( = 100%)
Differential Gain
dg dp
Differential Phase
-
0.01
0.03
deg
PP Signal / RMS Noise Gain SIGNAL PATH Delay Power Supply Rejection Ratio Off Isolation & Crosstalk
S/N AV td SIG PSRR
60 -0.02 -
70 -0.005 4 75 85 2.0 2.0 20 4 0 -
10 15 5 0.50 10 1.5 -35 +15 +1
dB dB ns dB dB dB dB mV mV k pF
= 1 kHz = 10 MHz
70 25 70 80 0 100 -
V A or B/V O V C/VA or B
SIG = 5 MHz (see note 1) SIG = 5 MHz (see note 2) Channel A or Channel B Channel A - Channel B
Output Offset Offset Difference Input Resistance Input Capacitance Output Resistance Output Capacitance Bandwidth Delay CONTROL CHANNEL Linearity Control Breakthrough Crossfade Balance Control Range
NOTE:
RIN CIN ROUT COUT BW0.1 tD CONT
=1 MHz
=1 MHz
-
pF MHz ns % dB mV V
at 0.1 dB, VIN = 150 mVp-p
15 -
VC = 0 to 1 V C =1 to 10 MHz V C = 0 to 1 V C = 3.58 MHz VC
-15 0
1. V A or B = +1 Vp-p, output taken from OUTPUT 2 . V C = +1 Vp-p, output taken from VA or VB
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DETAILED DESCRIPTION The GT4123B is a low power two quadrant video multiplier for use in a wide range of applications including broadcast and multimedia. The internal topology of the device is shown in Figure 1 below. The SPAN or control range is internally set so that a CONTROL voltage of 0 V completely cuts off Channel A and fully turns on Channel B. Similarly, a CONTROL voltage of 1 V will fully turn on Channel A and completely turn off Channel B.
IN A AMP A XA VCA + 1 + AMP D OUT
COMP
When VC is less than 0.5 V, VCA reduces and VCB increases in proportion so that less of Channel A and more of Channel B signal is transferred. Similarly, when VC is greater than 0.5 V, the opposite occurs.
+
IN B
+
AMP B
XB VCB
VCB = 0.5 - (VC - 0.5)
VCA = 0.5 + (VC - 0.5)
There is a small dead band at either end of the CONTROL input. The amount of dead band is about 100 mV. The CONTROL input can be preceded by an operational amplifier to overcome the dead band and level shift the control signal so that other than 0 to 1 V range can be used. The bandwidth of the CONTROL input is in the order of 20 MHz at 0.1 dB to allow for very fast KEY signals. The linear portion of the transfer characteristic has a linearity of better than 1.5%.
CONTROL
+
AMP C
2 + 3 +
(VC)
+
+
0.5V
REF
Fig. 1
Functional Block Diagram of the GT4123B
The outputs from the multipliers are applied to an analog summing circuit (a1) whose output feeds a wideband amplifier (Amp D) and presents the mixed signals to the outside world. The inverting nodes of each input 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, the GT4123B lends itself to high density, multi-function PC board layouts in devices such as RGB mixers and four layer keyers where close control law tracking is essential.
Each input is applied to a differential amplifier (AMP A and AMP B). From the amplifiers, the signals are passed to analog multiplier circuits (XA and XB) whose outputs are the product of the input signals and internally generated controlling voltages VCA and VCB. The internal control voltages are derived from a unity gain differential amplifier (AMP C) whose outputs (true and invert) are the difference between an internal 0.5 V reference voltage, and the externally applied CONTROL voltage. In addition, the internal DC offset of 0.5 V is applied to the controlling voltage summing circuits a2 and a3. Therefore, VCA = 0.5 V + (VC - 0.5 V) VCB = 0.5 V - (VC - 0.5 V) When the control input VC equals 0.5 volts, VCA = 0.5 V and VCB = 0.5 V, and 50% of each input signal passes to the output of the multiplier stages. and
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+5V 0.1
7
8
4
5 - 30pF
2
+5V
FROM NETWORK ANALYSER
150 75
0.1 1 4 CLC110 8 TO NETWORK ANALYSER
GT4123B
5 6 3 1
0.1 75 10k
5 0.1 -5V
0.1 -5V All resistors in ohms, all capacitors in microfarads unless otherwise stated
B A +1V
Fig. 2
Frequency Response, Cross Talk, Differential Gain & Phase Test Circuit
+5V
-5V 0.1
0.1
8 6
6dB AMPLIFIER GT4123B VA 75
5 7 4 3 2 1
VIDEO OUT 75
VB 150 75 5-30 pF VC
All resistors in ohms, all capacitors in microfarads unless otherwise stated
Fig. 3
Typical Application Circuit
GT4123B TYPICAL PERFORMANCE CURVES
0.2
(VS = 5V, unless otherwise specified)
0
0.1
-20
0
-40
CROSSTALK (dB)
GAIN (dB)
VC - CHANNEL B
-60
-0.1
VS = 12V
-0.2
-80
VS = 5V
VC - CHANNEL A
-100
-0.3
-0.4 0.1 1 10 100
-120 1 10 100
FREQUENCY (MHz)
FREQUENCY (MHz)
Fig. 4 Frequency Response
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Fig. 5 Crosstalk vs Frequency
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0.03
2.5
OUTPUT RESISTANCE (y)
10
0.02
2
0.01
1.5
dg / dp
0
dg dp
1
-0.01
-0.02
0.5
-0.03 1
0 0.1 1 10
FREQUENCY (MHz)
FREQUENCY (MHz)
Fig. 6 dg & dp vs Frequency
Fig. 7 Output Resistance vs Frequency
CH-B
100
CH-A
GAIN (%)
50
0
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
CONTROL VOLTAGE (VC)
Fig. 8 Control Characteristics
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 a 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. Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. (c) Copyright September 1994 Gennum Corporation. All rights reserved. Printed in Canada.
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