ADL5910 Data Sheet
Rev. 0 | Page 20 of 22
Figure 24. Evaluation Board Layout
Table 6. Evaluation Board Configuration Options
Component Function Notes Default Values1
RFIN_SW, RFOUT_SW,
R2, R45, R46, R47
RF switch path To operate the full input protection circuit, route
the input signal through the RFIN_SW and
RFOUT_SW SMA connectors. The values of the
R46, R2, R47, and R45 resistors determine the
coupling factor (20 dB) and insertion loss of the
asymmetrical splitter/coupler.
R2, R46 = 4.99 Ω (0402),
R45 = 62 Ω (0402),
R47 = 220 Ω (0402)
RFIN_ADL5910, R9, R16 RF input To drive the ADL5910 directly and bypass the
coupler/switch circuit, apply the RF input signal
to the RFIN_ADL5910 SMA. To operate in this
mode, remove R16 and place a 0 Ω resistor on R9.
R9 = open/DNI (0402),
R16 = 0 Ω (0402)
R6, R10 to R14, C2, C4, C5,
L1, L2
Input preemphasis and
termination network
The resistance on R6 combines with the internal
impedance to provide a broad 50 Ω input match.
C2 provides ac coupling between R6 and the RF
inpu.t (The RF input of the ADL5910 is internally
dc-coupled.) A broadband 50 Ω match is achieved
using 82.5 Ω on R6 and a 0.47 µF ac coupling
capacitor on C2. A pre-emphasis network can be
implemented by placing capacitors and inductors
on the pads to the left of R6.
R6 = 82.5 Ω,
R10 = 0 Ω (0402)
R11, R13 = open/DNI (0402),
R12, R14 = 0 Ω (0402),
C2 = 0.47 µF,
C4, C5 = open/DNI (0402),
L1, L2 = open/DNI (0402)
TCAL, R7, R8, VNEXT, VIN− VCAL threshold calibration The output voltage from the threshold calibration
pin (VCAL, Pin 3) is available on the yellow TCAL
clip lead. Use the voltage on this pin to determine
the correct threshold voltage that must be applied
to Pin 16 (VIN−) to set a particular RF power
threshold. This process includes two steps. First,
measure the output voltage on the TCAL yellow
clip lead with no RF signal applied to RFIN (this
voltage is approximately 750 mV). Second, apply
the RF input power to RFIN, which causes the
circuit to trip, and again measure the voltage on
the TCAL yellow clip lead. The difference between
these two voltages is equal to the voltage that
must be applied to VIN− during operation. This
voltage can be applied either to the VNEXT SMA
connector or to the VIN− yellow clip lead. This
voltage can also be set by the R8 mechanical
potentiometer on the board.
R7 = 1.1 kΩ (0603),
R8 = 1 kΩ (mechanical
potentiometer)