DEMO MANUAL DC1257B DESCRIPTION Demonstration circuit 1257B features the LTC®6416, a 2GHz low noise differential 16-Bit ADC buffer driving the LTC2208, a 16-bit 130Msps ADC. The DC1257B is supplied with a bandpass filter centered at 140MHz between the buffer and the ADC. The filter center frequency can be changed to optimize performance at different analog input frequencies. Both single-ended and differential configurations are supported at the inputs. The DC1257B has been LTC6416 2 GHz Low Noise Differential 16-Bit ADC Buffer developed from the DC996B-B, used to characterize the LTC2208 family of ADCs. Use the DC1257B with a DC890 FastDAACS and PScope™ software to collect time and frequency data. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation and PScope is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. QUICK START PROCEDURE Demonstration circuit 1257B is easy to set up. Refer to Figure 1 for proper measurement equipment setup. Table 1 describes the function of each SMA connector and default settings for the jumpers on the board. Table 1: DC1257B SMA Connector and Jumper Descriptions J2 (AIN+) Single-Ended/Differential Input. By default, this is configured as a single-ended input. Use this connector to supply an input to the DC1257B. When driven from a 50Ω signal source, no external termination necessary. J3 (AIN–) Differential Input. Not connected by default. Capacitor C23 can be installed and C25 removed to drive the DC1257B differentially. J4 (CLK) Single-Ended Input. This input is designed to be driven by an extremely low jitter 50Ω source. A sinusoidal input of up to 13dBm is recommended. JP1 (PGA) Programmable gain amplifier. Default to LOW Gain Mode. This sets the gain of the ADC amplifier to 1.0. JP2 (RAND) ADC Digital Output Randomization. Default to OFF. This disables randomization. JP3 (SHDN ADC) ADC Power Shutdown ADC. Default to EN. This results in normal operation. JP4 (DITH) ADC Internal Dither Enable. Default to OFF. This disables internal dither. HARDWARE SETUP The DC1257B requires DC890 FastDAACs data acquisition board with PScope System Software. The PScope System Software is available from the Linear Technology website at http://www.linear.com/software/. Apply power to the DC1257B Demonstration Circuit. Apply +3.6V across the pins marked OPT and GND, VS and GND. The DC1257B demonstration circuit requires up to 100mA from the OPT pin, and up to 700 mA from the VS pin. Supply power to the DC890B FastDAACS Board with an external 6V ±0.5V 1A supply on turrets on G7(+) and G1(–) or the adjacent 2.1mm power jack. Unless the DC890B detects external power it will not activate the LVDS mode of the Xilinx Spartan-III FPGA. The FPGA actively terminates the LVDS repeaters at the outputs of the LTC2208. dc1257bf 1 DEMO MANUAL DC1257B HARDWARE SETUP Apply Encode Clock to the DC1257B on the SMA connector marked “(J4) CLK". This transformer coupled input is terminated with a 100Ω at the secondary and a 100Ω at the ADC clock inputs. For best noise performance the clock input must be driven with a very low jitter source. The amplitude of the sinusoidal generator should be as large as possible, up to 13dBm. Bandpass filters on the clock and the analog input will improve the noise performance by reducing the wideband noise power of the signals. Data sheet FFT plots were taken with 10 pole LC filters made by TTE (Los Angeles, CA) to suppress signal generator harmonics, non-harmonically related spurs and broad band noise. Low phase noise (jitter) Agilent 8644B generators are used with TTE band pass filters for the CLK input and Analog input. Apply the Analog Input to the DC1257B on the SMA connector marked "(J2) AIN+". This input is capacitively coupled to a 1:4 Balun transformer TCM4-19+. Start and Configure the PScope data collection software for the FastDAACS DC890 by selecting AutoConfigure. If the board is not detected, up-date PScope for latest software and device list, and then select LTC2208 from the Configure→Device menu. You can also manually configure PScope for the LTC2208 by setting the parameters listed in Table 2. Collect Data by clicking on the “Collect” button. Time and frequency plots will be displayed in the PScope window. Consult the DC890 Quick Start Guide for additional information. Buffer ADC Interface The LTC6416 has been specifically designed to interface directly with high speed A/D converters. It is possible to drive the ADC directly from the LTC6416. In practice, however, better SFDR may be obtained by adding a few external components at the output of the LTC6416. Figure 2 shows the LTC6416 being driven by a 1:4 transformer which provides 6 dB of voltage gain while also performing single-ended to differential conversion. The differential outputs of the LTC6416 are lowpass filtered to drive the differential inputs of the LTC2208 ADC. In many applications, an anti-alias filter like this is desirable to limit the wideband noise of the amplifier. This is especially true in high performance 16-bit designs. The minimum recommended network between the LTC6416 and the ADC is simply two 5Ω series resistors, which are used to help eliminate resonances associated with the stray capacitances of PCB traces and the stray inductance of the internal bond wires at the ADC input, and the driver output pins. Table 3 suggests filter components for different input frequencies. Table 2: PScope User Configuration for LTC2208 Table 3. Suggested Components for the Filter USER CONFIGURE Bits 16 Channels 1 INPUT FREQUENCY LTC6416 OUTPUT RESISTORS R13 = R15 FILTERING CAPACITORS C20/C22/C24 Alignment 16 30MHz 50Ω 5.6pF/6.8pF/5.6pF FPGA Ld LVDS 70MHz 25Ω 5.6pF/6.8pF/5.6pF Bipolar [x] 140MHz 25Ω 1.5pF/1pF/1.5pF Positive Egde Clk [x] 250MHz 5Ω -/-/- dc1257bf 2 DEMO MANUAL DC1257B HARDWARE SETUP Figure 1. Demo Board DC1257B Layout 3.6V 680pF T1 TCM4-19+ 4 50Ω 6 2.2μF CLHI 3 2 + – 0.1μF 1 R36 100Ω V+ IN+ VCM IN– GND C39 CLLO 0.01μF 1.5pF 16 LTC2208 1pF OUT– GND VCM AIN+ OUT+ LTC6416 R15 100Ω 25Ω 3.3V DATA AIN– 25Ω 1.5pF 6416 F05 CLOCK (130MHz) Figure 2. DC1257B Simplified Schematic with Recommended Output Termination for Driving an LTC2208 16-Bit ADC at 140MHz dc1257bf 3 DEMO MANUAL DC1257B PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 1 12 C8-C12, C19, C25, C26, C28-C31 CAP., X7R, 0.1μF, 25V, 20% 0603 AVX, 06033C104MAT2A 2 4 C13, C14, C18, C27 CAP., X5R, 0.1μF, 16V, 10% 0402 AVX, 0402YD104KAT2A 3 1 C16 CAP., X5R, 2.2μF, 6.3V, 10% 0603 AVX, 06036D225KAT2A 4 1 C17 CAP., C0G, 220pF, 16V, 10% 0402 AVX, 0402YA221KAT2A 5 2 C20, C24 CAP., C0G, 1.5pF, 50V, ±.25pf 0402 AVX, 04025A1R5CAT2A 6 1 C22 CAP., C0G, 1.0pF, 50V, ±.25pf 0402 AVX, 04025A1R0CAT2A 7 0 C21, C23 (OPT) CAP., 0603 (OPT) 8 1 C32 CAP., X5R, 10μF, 25V, 20% 1206 Taiyo Yuden, TMK316BJ106ML 9 1 C33 CAP., X5R, 10μF, 6.3V, 20% 0805 Taiyo Yuden, JMK212BJ106MG 10 5 E1, E2, E3, E5, E7 TESTPOINT, TURRET, .061" pbf MILL-MAX, 2308-2-00-80-00-00-07-0 11 2 E4, E6 TESTPOINT, TURRET, .094" pbf MILL-MAX, 2501-2-00-80-00-00-07-0 12 4 JP1, JP2, JP3, JP4 HEADER 3-PIN 0.079 SINGLE ROW SAMTEC, TMM103-02-L-S 13 4 JP1, JP2, JP3, JP4 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G 14 3 J2, J3, J4 CON., SMA 50Ω EDGE-LAUNCH E.F. JOHNSON, 142-0701-851 15 0 L1 INDUCTOR, Ferrite Bead (OPT) 16 2 L2, L3 INDUCTOR, Ferrite Bead Murata, BLM18PG221SN1D 17 2 R3, R2 RES., CHIP, 10, 1/16W, 5% 0402 VISHAY, CRCW040210R0JNED 18 1 R4 RES., CHIP, 1k, 1/16W, 5% 0402 VISHAY, CRCW04021K00FKED 19 0 R5, R6, R8, R10-R12, R17, R18 (OPT) RES., CHIP, 0402 (OPT) 20 1 R7 RES., CHIP, 100, 1/16W, 5% 0402 VISHAY, CRCW0402100RJNED 21 2 R13, R15 RES., CHIP, 24.9, 1/16W, 1% 0402 VISHAY, CRCW040224R9FKED 22 2 R14A, R14B RES., CHIP, 100, 1/16W, 1% 0402 VISHAY, CRCW0402100FKED 23 1 R9, (Bal to#1450A) RES., CHIP, 10.0, 1/16W, 1% 0402 VISHAY, CRCW040210R0FKED 24 1 R16 RES., CHIP, 5.1k, 1/16W, 5% 0603 VISHAY, CRCW06035K10JNEA 25 2 R26, R19 RES., CHIP, 51.1, 1/16W, 1% 0402 VISHAY, CRCW040251R1FKED 26 1 R21 RES., CHIP, 100, 0.05W, 5% 0201 VISHAY, CRCW0201J100JNTD 27 3 R24, R25, R28 RES., CHIP, 4.99k, 1/16W, 1% 0603 VISHAY, CRCW06034K99FKEA 28 1 R27 RES., CHIP, 2k, 1/16W, 5% 0603 VISHAY, CRCW06032K00JNEA 29 0 R29 (OPT) RES., CHIP, 0603 (OPT) 30 1 T1 TRANSFORMER, TCM4-19+ MiNi-Circuits, TCM4-19+ 31 1 T2 TRANSFORMER, ETC1-1-13, SM-22 M/A-COM, MABA-001759-000000 32 1 U1 lot#T28918.2 DC=0837 I.C. LTC2208CUP 9 × 9 QFN LINEAR, LTC2208CUP#PBF 33 1 U2 lot#J20129.1 DC=0808 I.C. LTC6416CDDB DFN 10-PIN (3 × 2) LINEAR, LTC6416CDDB#PBF 34 1 U3 I.C., 24LC025, TSSOP-8 MICROCHIP, 24LC025 I /ST 35 1 U4 see file for #'s IC., LT1963AEST-3.3 SOT-223 LINEAR, LT1963AEST-3.3#PBF 36 4 (STAND-OFF) STAND-OFF, NYLON 0.25" KEYSTONE, 8831(SNAP ON) 37 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1257B 38 1 STENCIL STENCIL 1257B dc1257bf 4 J3 J2 C23 OPT C19 0.1μF C25 0.1μF C21 OPT 5 4 • T1 E2 E1 • CLLO E3 R18 OPT R17 OPT VCC 3 2 1 R12 OPT R11 OPT VCC TCM4−19+ CLHI VCM C26 0.1μF C18 0.1μF R10 OPT R8 OPT VCC CLK C27 0.1μF R14B 100Ω R14A 100Ω C13 0.1μF J4 5 4 3 2 1 C28 0.1μF CLLO IN− IN+ CLHI VCM GND OUT− OUT+ 6 7 8 9 10 VCC C29 0.1μF 5 4 • • 1 2 3 T2 MABA-007159-000000 11 GND V+ GND LTC6416CDDB R9 1k Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. R26 51.1Ω C16 2.2μF C9 0.1μF VDD C10 0.1μF GND VS 3.6V TO 20V R21 100Ω C24 1.5pF C22 1pF C20 1.5pF C8 0.1μF E7 1 3 VDD E6 E4 VCM 2 1 2 OFF VDD VDD GND ENC− GND ENC+ GND AIN− IN GND A + VDD VDD GND VCM GND SENSE VS ON OFF C32 10μF 25V 2 JP3 SHDN ADC 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 SHDN EN LOW R2 10Ω VDD VDD R3 10Ω 1 2 58 IN 2 GND OUT LT1963AEST-3.3 JP4 DITH 56 LTC2208CUP 3 54 C33 10μF 6.3V 49 50 DB10 DB11 DB12 DB13 DB14 DB15 OFB CLKCOUTB CLKCOUTA DA0 DA1 DA2 DA3 DA4 DA5 DA6 OVP L3 BLM18PG221SN1D L2 BLM18PG221SN1D L1(opt.) BLM18PG221SN1D OVP VDD VCC OVP 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 C12 0.1μF Figure 3. Demo Board DC1257B Schematic (Test Circuit B) C30 0.1μF R19 51.1Ω R15 24.9Ω R13 24.9Ω C17 680pF C14 0.1μF EXTREF R4 1k 64 HI 63 JP2 RAND R5 62 PGA 17 RAND 18 GND 19 JP1 PGA R6 VDD OPT 61 MODE 20 3 1 3 OPT R7, 100Ω SHDN 60 LVDS DITH 59 OFA 1 DB3 24 DB0 21 57 DA13 55 26 DA15 22 DA14 DB2 23 DA12 DB4 25 53 DA11 DB5 52 DA10 27 DB6 51 DA9 DB7 27 DA8 DB8 29 DA7 DB9 30 OGND OGND 31 OVDD OVDD 32 DB1 3 GND 65 VDD E5 C11 0.1μF OPT R27 2k 4 3 2 1 A0 A1 A2 VSS VCC WP SCL SDA 24LC025 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 5 6 7 8 R29 OPT R24 4.99k 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 J1 EDGE-CON (GOLD FINGER) C31 0.1μF R28 4.99k R25 4.99k R16 5.1k OVP 6416 F09 DEMO MANUAL DC1257B SCHEMATIC DIAGRAM dc1257bf 5 DEMO MANUAL DC1257B DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation dc1257bf 6 Linear Technology Corporation LT 0812 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2012