AD809
USING THE AD809
Ground Planes
V
CC1
Use of one ground plane for connections to both analog and
digital grounds is recommended.
Use of a 10
µF
capacitor between V
CC
and ground is recom-
mended. Care should be taken to isolate the +5 V power trace
to V
CC2
(Pin 3). The V
CC2
pin is used inside the device to pro-
vide the CLKOUT/CLKOUTN signals.
Use of a trace connecting Pin 14 and Pin 6 (AV
CC2
and V
CC1
respectively) is recommended. Use of 0.1
µF
capacitors between
IC power supply and ground is recommended. Power supply
decoupling should take place as close to the IC as possible.
Refer to the schematic, Figure 5, for advised connections.
Transmission Lines
Power Supply Connections
Synthesizer Input
TTL/CMOSIN
500Ω
2*I
TTL
80µA
OR
0µA
2*I
TTL
80µA
OR
0µA
V
EE
V
CC1
7.5kΩ
7.5kΩ
Use of 50
Ω
transmission lines are recommended for PECL
inputs.
Terminations
Synthesizer Input
CLKIN/CLKINN
PECL INPUT
500Ω
I
TTL
500Ω
40µA
V
EE
40µA
Termination resistors should be used for PECL input signals.
Metal, thick film, 1% tolerance resistors are recommended.
Termination resistors for the PECL input signals should be
placed as close as possible to the PECL input pins.
Connections from the power supply to load resistors for input
and output signals should be individual, not daisy chained. This
will avoid crosstalk on these signals.
Loop Damping Capacitor, C
D
460Ω
460Ω
V
CC2
PLL Differential
Output Stage–
CLKOUT/CLKOUTN
2.6mA
V
EE
DIFFERENTIAL
OUTPUT
A ceramic capacitor may be used for the loop damping capaci-
tor. A 22 nF capacitor provides a damping factor of 10.
Figure 4. Simplified Schematics
C1
0.1µF
J5
R5
301Ω
R1
49.9Ω
R2
49.9Ω
50Ω STRIP LINE
EQUAL LENGTH
16-PIN SOIC
SOLDERED TO BOARD
JUMPER
W1
GND
MUX
EXT
+5V
R16
301Ω
JUMPER
W3
R14
49.9Ω
R15
49.9Ω C13 0.1µF
C14 0.1µF
C10
R13
49.9Ω
C15 0.1µF
J6
CLKIN
J7
CLKINN
C6
0.1µF
R3
100Ω
R4
100Ω
R11
154Ω
R12
154Ω
TP1
CD
TP2
VECTOR PINS SPACED FOR THROUGH-HOLE
CAPACITOR ON VECTOR CUPS.
COMPONENT SHOWN FOR REFERENCE ONLY.
C8
6 V
CC1
7 CF1
8 CF2
GUARD RING
NOTE:
C11
10µF
TP4
GND
C7–C10 ARE 0.1µF BYPASS CAPACITORS
RIGHT ANGLE SMA CONNECTOR
OUTER SHELL TO GND PLANE
ALL RESISTORS ARE 1% 1/8 WATT SURFACE MOUNT
TPx
TEST POINTS ARE VECTOR PINS
AV
CC1
11
TTL/CMOSIN 10
AV
EE
9
J8
CMOS/TTL IN
C12
0.1µF
J1 C2 0.1µF
ECL INN
J2 C3 0.1µF
ECL IN
J3 C4 0.1µF
CLKOUTN
J4 C5 0.1µF
CLKOUT
R6
3.65kΩ
JUMPER
W2
AD809
1 PECLINN
2 PECLIN
V
EE
16
MUX 15
AV
CC2
14
CLKIN 13
CLKINN 12
C9
R17
3.65kΩ
R7 100Ω
R8 100Ω
C7
3 V
CC2
4 CLKOUTN
5 CLKOUT
TP3
+5V
Figure 5. Evaluation Board Schematic
REV. A
–5–
AD [ ANALOG DEVICES ]
