QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 714 TRIPLE HIGH SPEED VIDEO AMPLIFIER LT6553 DESCRIPTION Demonstration Circuit 714 (DC714) is a Triple High the performance that is achieved with this evaluation Speed Video Amplifier featuring the LT6553. This circuit board. is designed to demonstrate DC-coupled performance in Design files for this circuit board are available. Call either split- or single-supply operation. Table 1 indicates the LTC factory. Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE Split supply operation, Min/Max 2.3V/6V Supply Voltage Single supply operation, Min/Max +4.5/+12V Input Impedance, INR, ING, INB 75 , dc-coupled to ground Output Impedance, OUTR, OUTG, OUTB 75 , dc-coupled CAL trace Impedance 75 nominal Outputs terminated into 75 0dB nominal Gain Outputs terminated into High impedance +6dB nominal Bandwidth 3dB, Small Signal 600MHz typical Worst-case All Hostile, 10MHz 75dB typical Crosstalk Worst-case All Hostile, 100MHz 50dB typical 3.3V Split Supply, No Output Clipping 0.7V Input Signal Voltage Range 5.0V Split Supply, No Output Clipping 1.5V (note: feedback resistor connections tied to ground on printed circuit) +9.0V Single Supply, No Output Clipping +1.0 to +3.5V Logic Low Voltage (Amplifiers ON), DGND = 0V 0.8V On/Off Control Input Logic High Voltage (Amplifiers OFF), DGND = 0V 2.0V (5.5V max) OPERATING PRINCIPLES DC714 provides three identical channels of wideband JP2, which allows the DGND to be strapped to the local signal amplification suitable for driving HDTV or high- analog ground (AGND) for example, when the logic resolution RGB video display cables. Each amplifier sec- source is floating or none is used during the evaluation. tion of the LT6553 provides a fixed gain of 2, and with DGND may be left uncommitted with JP2 in the FLOAT series back-termination at the outputs (included on the position. board), results in unity gain transmission of a video sig- Another jumper, JP1, allows the LT6553 to be forced to nal to a destination load. Each input is terminated to an ENABLE condition. If JP1 is left in the EXTernal posi- analog ground to properly load the input signal cable. tion, then enabling the LT6553 is accomplished by pull- To minimize ingress of external digital ground noise, the ing down the EN connection to a level near that of DGND DGND logic reference input is decoupled from analog via connection to E1 or J1. A pull-up resistor internal to ground within the LT6553. DC714 includes a jumper, the LT6553 will provide a default shutdown mode of op- 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 714 TRIPLE HIGH SPEED VIDEO AMPLIFIER eration if the control input is left open-circuit. NOTE: DO cuit board and connector effects to be eliminated from NOT open-circuit EN if V+ is more than 5.5V above the transmission measurements. DGND refer to LT6553 datasheet for application details JP3 is provided as a convenience to eliminate having to in this situation. externally short V to GND in the case of SINGLE supply A CAL trace is also provided on DC714 to provide a operation. Leave JP3 in the DUAL position when using means of precision calibration for a Network Analyzer split supplies. (use the CAL connections when performing the THRU Figure 4 shows the material list of the components used transmission calibration). The CAL trace has the same by DC714, and Figure 5 shows the electrical intercon- electrical performance and delay as the transmission nection. lines of the three signal channels, thereby allowing cir- QUICK START PROCEDURE Demonstration Circuit 714 is easy to set up to evaluate converters, etc. in place, and using the DC714 CAL the performance of the LT6553. Refer to Figure 1 for trace as the reference 0dB path. proper measurement equipment setup and follow the 5. Energize the power supply. procedure below: 6. Connect the Network Analyzer (if used) to the appro- NOTE: Due to the Ultra High Frequencies (UHF) involved, priate channels to measure frequency response and RF measurement practices are required to accurately crosstalk as desired. Figure 2 shows a typical trans- evaluate the performance of the LT6553. mission plot. 1. Place jumpers in the following positions: 7. For video-signal evaluation, connect a component- JP1 ENABLE video signal source to the inputs and a monitor and/or video analyzer to the outputs, using equal-length ca- JP2 AGND bling amongst the three video channels. Figure 3 JP3 DUAL shows a typical pulse response. 2. Prior to connecting the power supply, preset the out- 8. To evaluate the shutdown mode, disconnect or relo- put voltages to 5V, or to the desired level, if different. cate the JP1 jumper to the EXT position (with no con- nections made at EN, or if present, a logic high pro- 3. With power off, connect the power supplies to V+, V, vided). and GND using banana-plug cables. 4. If using a Network Analyzer, perform the THRU transmission cal with all cabling, adapters, impedance 2