Pentek 6230 Operating Manual page 100

AD6644
EVALUATION BOARD
The evaluation board for the AD6644 is straightforward,
containing all required circuitry for evaluating the device. The
only external connections required are power supplies, clock,
and the analog inputs. The evaluation board includes the option
for an onboard clock oscillator for ENCODE.
Power to the analog supply pins of the AD6644 is connected via
the power terminal block (PCTB2). Power for the digital interface
is supplied via pin 1 of J6. The J2 connector mates directly with
SoftCell Receive Signal Processor (AD6620, AD6624) evaluation
boards, allowing complete evaluation of system performance.
The analog input is connected via a BNC connector AIN, which
is transformer-coupled to the AD6644 inputs. The transformer
has a turns ratio of 1:4 to reduce the amount of input power
required to drive the AD6644.
Item Quantity Reference
1 2 C1, C2
2 19 C3, C7, C8, C9, C10, C11, C16, C30, C31,
C32, C4, C22, C23, C24, C25, C26, C27,
C28, C29
3 8 C12, C13, C14, C17, C18, C19, C20, C21
4 1 CR1
5 1 E3, E4, E5
6 4 F1, F2, F3, F4
7 2 J1, J6
8 1 J2
9 1 J3
10 2 J4, J5
11 1 R1
12 1 R2
13 4 R3, R4, R5, R8
14 2 R6, R7
15 1 R9
16 1 R10
17 1 R35
18 30 R36, R37, R38, R39, R40, R41, R42, R43,
R44, R45, R46, R47, R48, R49, R50, R51,
R52, R53, R54, R55, R56, R57, R58, R59,
R60, R61, R62, R63, R64, R65
19 2 T2, T3
20 1 U1
21 2 U2, U7
22 1 U3
23 2 U4, U6
24 1 U5
The Encode signal may be generated using an onboard crystal
oscillator, U5. The on-board oscillator may be replaced by an
external encode source via the SMA connector labeled OPT_CLK
or BNC connector labeled ENCODE. If an external source is
used, it must be a high-quality and very low-phase noise source.
The AD6644 output data is latched using 74LCX574 (U7, U2)
latches. The clock for these latches is determined by selecting
jumper E3–E4 or E4–E5. E3 to E5 is a just a gate delayed ver-
sion of the clock, while connecting E4 to E5 utilizes the Data
Ready of the AD6644 to latch the output data. A clock is also
distributed with the output data (J2) that is labeled BUFLAT
(Pin 19 and 20, J2).
AD6644ST/PCB Bill of Material
Description
Tantalum Chip Capacitor 10 µF
Ceramic Chip Capacitor 0508, 0.1 µF
Ceramic Chip Capacitor 0508, 0.01 µF
HSMS2812 Surface Mount Diode
3-Pin Header
Ferrite (Optional)
PCTB2
50-Pin Double Row Header
SMA Connector
BNC Connector
Surface-Mount Resistor 1206, 100 Ω
Surface-Mount Resistor 1206, 60.4 Ω
Surface-Mount Resistor 0805, 499 Ω (Optional,
DC-Coupling Only)
Surface-Mount Resistor 0805, 25 Ω
Surface-Mount Resistor 0805, 348 Ω
Surface-Mount Resistor 0805, 615 Ω
Surface-Mount Resistor 0805, 49.9 Ω
Surface-Mount Resistor 0402, 100 Ω
Surface-Mount Transformer Mini-Circuits T4–1, 1:4 Ratio
AD6644AST 14-Bit 65 MSPS A/D Converter
74LCX574 Octal Latch
AD8138 Single-to-Differential Amplifier (Optional – DC
Coupling Only)
NC7SZ32 Two Input OR Gate
CTS Reeves Full-Size MX045 Crystal Clock Oscillator
–14–
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