DC1774A-A Analog Devices

DEMO MANUAL DC1774A-A LTC6430-15 100MHZ to 300MHZ Differential ADC Driver/IF Amplifier Description Demonstration circuit 1774A-A is a differential ADC Because the LTC6430-15 has 100 differential input and driver/IF amplifier featuring the LTC 6430-15. It is part output impedance, the demo circuit uses transformers to of the DC1774A demo board family supporting the convert the impedance to 50 single-ended allowing easy LTC643X-YY amplifier series. The DC1774A-A is opti- evaluation with commercially available RF test equipment. mized for a frequency range of 100MHz to 300MHz and Design files for this circuit board are available at utilizes a minimum of passive external components to S11, S12 , S22 (dB) DEMO MANUAL DC1774A-A Block Diagram GND V CC 8, 14, 17, 23 9, 22 AND PADDLE 25 BIAS AND TEMPERATURE COMPENSATION +IN +OUT 24 18 T DIODE 16 IN OUT 7 13 GND 8, 14, 17, 23 AND PADDLE 25 dc1774aa F01 Figure 1. LTC6430-15 Device Block Diagram o NOMINAL WORKING Demo Circuit 1774A-A is a highly linear fixed-gain ampli- FREQUENCY RANGE fier. The LTC6430-15 is internally matched to a 100 18 0 differential source and load impedance from 20MHz to 16 4 1300MHz. Due to the unpopularity of 100 differential S21 test equipment, transformers have been added to convert 14 8 S11 impedance from differential 100 to single-ended 50 12 12 for the input and the output ports. The frequency range S22 10 16 of the circuit is limited by the balun transformers. Hence, S12 this demo board works best with a frequency range from 8 20 100MHz to 300MHz. Figure2 shows the performance of 6 24 the demo board. 4 28 0 100 200 300 400 FREQUENCY (MHz) dc1774aa F02 Figure 2. Demo Board DC1774A-A S-Parameters dc1774aaf 2 S21 (dB) peration