Datasheet
AD8368
Rev. B | Page 17 of 20
EVALUATION BOARD
The standard evaluation board schematic and layout artwork is
presented in Figure 41 through Figure 44. The evaluation board
is fabricated on a multilayer FR-4 board, with 50 Ω-controlled
impedance transmission lines for the RF input and output traces.
The board is powered by a single supply in the 4.5 V to 5.5 V
range. The power supply is decoupled by 0.1 μF and 1 nF capacitors
at each power supply pin. Additional decoupling, in the form
of a series resistor or inductor at the supply pins, can also be added.
Table 6 details the various configuration options of the
evaluation board.
05907-043
V
POS
VPOS1 VPOS2 VPOS3
ICOMGAIN
ENBL
VPSI
VPSI
MODE
ICOM
INPT
OCOM
OUTP
VPSO
VPSO
VPSI
VPSI
ICOMDETO
ICOMHPFL
DECLDECL
DECLDETI
VPSIOCOM
AD8368
C20
1nF
C2
5.6pF
C11
1nF
C14
0.1µF
R11
0Ω
V
POS2
C12
1nF
C15
0.1µF
R12
0Ω
V
POS3
C
OUT
10nF
OUTPUT
R31
OPEN
R32
OPEN
R30
OPEN
DET_IN
C1
OPEN
GAIN
C23
10nF
C4
1nF
C6
1nF
JP4
GAIN
C13
0.1µF
DET_OUT_TP
R35
OPEN
R3
215Ω
L1
10nH
C
IN
10nF
INPU
T
SW1
SW2
LOW
HI
ON
OFF
C10
1nF
R1
10kΩ
R2
10kΩ
ENABLE
R10
0Ω
VPOS1
Figure 40. Evaluation Board
Table 6. Evaluation Board Configuration Options
Component Function Default Conditions
R1, R2, R3, L1
Pull-Down Resistors for MODE and ENBL. RL network. Prevent potential instability impact
due to PCB parasitics and/or certain extreme conditions (see the Stability and Layout
Considerations section).
R1 = R2 = 10 kΩ
R3 = 215 Ω
L1 = 10 nH
R10, R11, R12,
C10, C11, C12,
C13, C14, C15
Supply Decoupling. Jumpers, power supply decoupling resistors, and filter capacitors.
R10 = R11 = R12 = 0 Ω
C10 = C11 = C12 = 1 nF
C13 = C14 = C15 = 0.1 μF
C
IN
RF Input. C
IN
provides dc block for RF input. C
IN
= 10 nF
C
OUT
RF Output. C
OUT
provides dc block for RF output. C
OUT
= 10 nF
R31, R32
Feedback Path for AGC Operation. For a default setpoint of 63 mV rms, set R31 = 0 Ω and
remove R32. For other AGC setpoints, rms voltage = (1 + n) × 63 mV rms, where n = R31/R32.
R31 = R32 = Open
(VGA mode)
R35 Populate with 0 Ω to feed detector output RSSI voltage to DET_OUT_TP. R35 = Open
C23 Sets the corner frequency of the output offset control loop high-pass filter. C23 = 10 nF
C1, R30
Used for driving the detector externally. Set R30 to 50 Ω for matching. Set C1 to be a large
ac coupling capacitor.
C1 = Open
R30 = Open
C6 DETO Capacitor. Needs to be made larger for lower data rates (see the AGC Operation section). C6 = 1 nF
C20, C2, C4
DECL Capacitor. Needs to be adjusted based on RF frequency in AGC operation (see the
AGC Operation section).
C20 = C4 = 1 nF
C2 = 5.6 pF