Datasheet

AD6644
Rev. D | Page 18 of 24
EVALUATION BOARD
The schematic of the evaluation board (see Figure 32) repre-
sents a typical implementation of the AD6644. A multilayer
board is recommended to achieve best results. It is highly
recommended that high quality, ceramic chip capacitors be
used to decouple each supply pin to ground directly at the
device. The pinout of the AD6644 facilitates ease of use in
the implementation of high frequency, high resolution design
practices. All of the digital outputs are segregated to two sides
of the chip, with the inputs on the opposite side for isolation
purposes.
Care should be taken when routing the digital output traces. To
prevent coupling through the digital outputs into the analog
portion of the AD6644, minimal capacitive loading should be
placed on these outputs. It is recommended that a fanout of
only one gate should be used for all AD6644 digital outputs.
The layout of the encode circuit is equally critical. Any noise
received on this circuitry results in corruption in the digitization
process and lower overall performance. The encode clock must be
isolated from the digital outputs and the analog inputs.
Table 10. AD6644/PCB Bill of Materials
Qty. Reference ID
1
Description Manufacturer Supplier Part No.
1 PCB Printed circuit board, AD6644/AD6645 engineering
evaluation board
Moog 6645EE01D REV D
4 C1, C2, C31, C38 Capacitor, tantalum, SMT BCAPTAJC, 10 μF, 16 V, 10% Kemet T491C106K016AS
8 C3, C7 to C10, C16, C30
2
, C32 Capacitor, ceramic, SMT 0508, 0.1 μF, 16 V, 10% Presidio Components 0508X7R104K16VP3
9 C4, C15, C22 to C26, C29, (C33)
3
,
(C34)
3
, C39
Capacitor, ceramic, SMT 0805, 0.1 μF, 25 V, 10% Panasonic ECJ-2VB1E104K
0 (C5, C6)
3
Capacitor, ceramic, SMT 0805, 0.01 μF, 50 V, 10% Panasonic ECJ-2YB1H103K
10 C11 to C14, C17 to 21, C40 Capacitor, ceramic, SMT 0508, 0.01 μF, 50 V, 0.2% Presidio Components 0508X7R103M2P3
0 (C27, 28) Capacitor, ceramic, SMT 0805, select
1 CR1
3
Diode, dual Schottky HSMS2812, SOT-23, 30 V, 20 mA Panasonic MA716-(TX)
1 E1 Install jumper (across OPT_LAT and BUFLAT)
5 F1 to F5 EMI suppression ferrite chip, SMT 0805 Steward HZ0805E601R-00
1 J1-H Header, 6-pin, pin strip, 5 mm pitch Wieland Z5.530.0625.0
1 J1 Pin strip, 6-pin, 5 mm pitch Wieland 25.602.2653.0
1 J2 Header, 40-pin, male, right angle Samtec TSW-120-08-T-D-RA
2 (J3), J4, J5 Connector, gold, male, COAX., SMA, vertical Johnson Components™ 142-0701-201
1 L1 Inductor, SMT, 1008-ct package, 4.7 nH Coilcraft® 1008CT-040X-J
0 (R1)
3
Resistor, thick film, SMT 0402, 100 Ω, 1/16 W, 1% Panasonic ERJ-2RKF1000V
0 (R2) Resistor, thick film, SMT 1206, 60.4 Ω, 1/8 W, 1% Panasonic ERJ-8ENF60R4V
2 (R3 to R5)
2
, (R8)
2
, R9, R10 Resistor, thick film, SMT 0805, 500 Ω, 1/10 W, 1% Panasonic ERJ-6ENF4990V
2 R6 and R7 Resistor, thick film, SMT 0805, 25.5 Ω, 1/10 W, 1% Panasonic ERJ-6ENF25R5V
0 (R11)
3
, (R13)
3
Resistor, thick film, SMT 0805, 66.5 Ω, 1/10 W, 1% Panasonic ERJ-6ENF66R5V
0 (R12)
3
, (R14)
3
Resistor, thick film, SMT 0805, 100 Ω, 1/10 W, 1% Panasonic ERJ-6ENF1000V
1 R15
2
Resistor, thick film, SMT 0402, 178 Ω, 1/16 W, 1% Panasonic ERJ-2RKF1780X
1 R35 Resistor, thick film, SMT 0805, 49.9 Ω, 1/10 W, 1% Panasonic ERJ-6ENF49R9V
4 RN1 to RN4 Resistor array, SMT 0402; 100 Ω; 8 ISO RES.,1/4 W; 5% Panasonic EXB2HV101JV
2 T2
3
, T3
2
Transformer, ADT4-1WT, CD542, 2 MHz to 775 MHz Mini-Circuits® ADT4-1WT
1 U1 IC, 14-bit, 65 MSPS ADC, LQFP-52 Analog Devices AD6644
2 U2, U7 IC, SOIC-20, OCTAL D-type flip-flop Fairchild 74LCX574
0 (U3)
2
IC, SOIC-8, low distortion differential ADC driver Analog Devices AD8138ARM
2 U4, U6 IC, SOT-23, tiny logic UHS 2-input or gate Fairchild NC7SZ32
0 (U8)
3
IC, SOIC-8, differential receiver Motorola MC100LVEL16
1 Y1 Clock oscillator, 65 MHz CTS Reeves MX045-65
4 Y1-PS Pin sockets, closed end AMP 5-330808-3
4 STDOFF Circuit board support RICHO CBSB-14-01
1
Reference designators in parentheses are not installed on standard units.
2
AC-coupled AIN is standard: R3, R4, R5, R8, and U3 are not installed. If dc-coupled AIN is required, C30, R15, and T3 are not installed.
3
AC-coupled encode is standard: C5, C6, C33, C34, R1, R11 to R14, and U8 are not installed. If PECL encode is required, CR1 and T2 are not installed.