QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1016 5V TRIPLE HIGH SPEED VIDEO AMPLIFIER LT6557 / LT6558 DESCRIPTION Demonstration Circuit 1016 (DC1016) is a 5V Triple High eration. The LT6557 and LT6558 include automatic in- Speed Video Amplifier featuring the LT6557 or LT6558 in ternal biasing that is programmable with one resistor. DFN packaging. The DC1016AA version demonstrates Table 1 indicates the performance that is achieved with the gain-of-two LT6557, while the DC1016AB features this evaluation board. the unity-gain LT6558. The board is designed to demon- Design files for this circuit board are available. Call strate AC-coupled performance in 5V single-supply op- the LTC factory. Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE Supply Voltage Recommended Min/Max +5V/+10V + Supply Current V = 5V 65mA 75W to ground, ac-coupled internal Input Impedance, INR, ING, INB signals Output Impedance, OUTR, OUTG, OUTB 75W, ac-coupled CAL trace Impedance 75W nominal Outputs terminated into 75W 0dB nominal Gain (A version) Outputs terminated into High impedance +6dB nominal Outputs terminated into 75W 6dB nominal Gain (B version) Outputs terminated into High impedance 0dB nominal V = 125mV (-16dBm), 3dB, R =75W 7Hz to 380MHz typical IN PP L Frequency Response V = 125mV (-16dBm), 0.1dB, R =75W 7Hz to 130MHz typical IN PP L Worst-case All Hostile, 10MHz 75dB typical Crosstalk Worst-case All Hostile, 100MHz 55dB typical 0.6V about average dc (A) Input Signal Voltage Range +5.0V Supply, No Output Clipping 1.2V about average dc (B) + Logic Low Voltage (Amplifiers ON) (V 2)V On/Off Control Input + Logic High Voltage (Amplifiers OFF) (V 0.5)V or open circuit OPERATING PRINCIPLES DC1016 provides three identical channels of wideband series back-termination at the outputs (included on the signal amplification suitable for driving HDTV or high- board), which results in unity gain transmission of a resolution RGB video display cables. The LT6557 pro- video signal to a destination load (75W for A 1kW or vides a gain of two for driving terminated video cables more for B). Each input is dc terminated to analog and the LT6558 has unity gain for use with high- ground to properly load the input signal cable. The in- impedance loads. Each amplifier section is provided with puts are ac-coupled after termination to eliminate input 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1016 5V TRIPLE HIGH SPEED VIDEO AMPLIFIER biasing requirements. The outputs are also ac-coupled sistor internal to the IC will provide a default shutdown to eliminate the amplifier bias from passing to the load. mode of operation if the control input is left open-circuit this allows open-collector type control of the amplifiers. The dc-biasing at the amplifier inputs is programmed by the R7 resistor value. The internal input biasing circuitry A CAL trace is also provided on DC1016 to provide a behaves as a soft clamp, minimizing the need for exter- means of precision calibration for a Network Analyzer nal components in the signal path. The bias point is rela- (use the CAL connections when performing the THRU tively fixed and independent of supply voltage changes. transmission calibration). The CAL trace has the same R7 and the input coupling capacitors may be removed if electrical performance and delay as the transmission direct dc drive to the amplifiers is desired. lines of the three signal channels, thereby allowing most circuit board and connector effects to be eliminated from A jumper, JP1, allows the LT6557 or LT6558 to be forced the transmission measurements. to an ENABLE condition. If JP1 is left in the EXTernal position, then enabling the LT6557 or LT6558 is accom- Figure 4 shows the material list of the components used plished by pulling down the EN connection at least 2V by DC1016, and Figure 5 shows the electrical intercon- + below V by connection to E1 or J1. A 40kW pull-up re- nection. QUICK START PROCEDURE Demonstration Circuit 1016 is easy to set up to evaluate converters, etc. in place, and using the DC1016 CAL the performance of the LT6557 or LT6558. Refer to trace as the reference 0dB path. Figure 1 for proper measurement equipment setup and 5. Energize the power supply. follow the 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 board. 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- 2. Prior to connecting the power supply, preset the out- bling amongst the three video channels. Figure 3 put voltage to +5V, or to the desired level, if different. shows a typical pulse response. + 3. With power off, connect the power supply to V and 8. To evaluate the shutdown mode, disconnect or relo- GND using banana-plug cables. cate the JP1 jumper to the EXT position (with no con- 4. If using a Network Analyzer, perform the THRU nections made at EN, or if present, a logic high pro- transmission cal with all cabling, adapters, impedance vided). 2