DEMO CIRCUIT DC1108 QUICK START GUIDE DEMO CIRCUIT 1108 650MHZ DIFF. ADC DRIVER / DUAL SELECTABLE-GAIN AMPLIFIER QUICK START GUIDE LT6411 650MHz Differential ADC Driver / Dual Selectable Gain Video Amplifier DESCRIPTION Demonstration circuit 1108 features the LT6411 Dual Am- speed signal chain applications. The LT6411 accepts single- plifier and ADC Driver. It incorporates a variety of passive ended or differential inputs with almost no difference in dis- components to support configurations for varied applica- tortion performance. The topology of the LT6411 allows the tions, including large AC-coupling capacitors for video ap- flexibility of selecting various gains without the use of extra plications. Single-ended or differential input and output con- resistors. The LT6411 consumes only 16mA of supply cur- figurations are possible with on-board component changes. rent (80mW) when enabled, and includes a low-power The LT6411 supports both a single +5V power supply as shutdown mode for additional power savings. well as split 5V supplies. Design files for this circuit board are available. Call the LTC factory. The LT6411 is a high-speed differential amplifier with supe- , LTC and LT are registered trademarks of Linear Technology Corporation. rior distortion and noise performance, perfect for demand- ing video distribution, communications, and other high- QUICK START PROCEDURE Table 1 shows the function of each SMA connector on the 3. Observe the output via J2 and/or J3. The default gain is board. Refer to Figure 1 for the connection diagram and +2, relative to the single-ended input. The outputs have follow the procedure below: 75 series resistors. 1. Connect the power supply as shown. The power labels of Table 1: DC1108 SMA Connector Descriptions VCC and GND are used to apply a single +5V to +10V CONNECTOR FUNCTION supply by default, VEE is connected to GND through re- J1 (IN1) Board Input. Use this connector to supply an input to the DC1108. Drive from a 75 signal source, no exter- sistor R21. Jumper JP1 enables or shuts down the nal termination necessary. Resistor R6 provides a 75 LT6411. impedance match. Input is AC coupled by default. J4 (IN2) Board Input. Connected to GND through resistor R20 by 2. Apply an input signal to J1. A low-distortion, low default. Resistor can be removed to drive the DC1108 noise signal source with an external high-order filter differentially. Input is AC coupled by default. will yield the best performance. DC1108s input is J2 (OUT1) Output. By default, connected by a 75 series resistor impedance-matched to 75 no external termination for video cable driving. is necessary. To use a 50 source instead of a 75 J3 (OUT2) Output. By default, connected by a 75 series resistor for video cable driving. source, replace impedance-matching resistor R6 with a 57.6 0603 resistor. 1 DEMO CIRCUIT DC1108 QUICK START GUIDE 650MHZ DIFF. ADC DRIVER / DUAL SELECTABLE-GAIN AMPLIFIER Power Supply (+5V) Optional Supply (-5V) (Remove R21) Input (Z = 75) Differential Output with 75 series resistors for cable driving Figure 1. DC1108 Default Board Evaluation Setup Single Ended Input, AC-Coupled. Gain = +2 Figure 2. Block Diagram of LT6411 Internal Amplifiers and Resistors 2