ADL5502-EVALZ AD [Analog Devices], ADL5502-EVALZ Datasheet - Page 10

• Manufacturer Part Number: ADL5502-EVALZ
• Description: 800 MHz to 3800 MHz Crest Factor Detector
• Manufacturer: AD [Analog Devices]

ADL5502
APPLICATIONS
BASIC CONNECTIONS
Figure 17 shows the basic connections for the ADL5502. The
device is powered by a single supply between 2.5 V and 3.5 V,
with a quiescent current of 5 mA. The VPOS pin is decoupled
using 100 pF and 0.1 μF capacitors.
Placing a single 75 Ω resistor at the RF input provides a
broadband match of 50 Ohms. More precise resistive or
reactive matches can be applied for narrow frequency band use
(see impedance plot, Figure 7).
The rms averaging can be augmented by placing additional
capacitance at CFLT. The ac residual can be further reduced by
increasing the output capacitance, COUT. The combination of
the internal 100 Ω output resistance and COUT produce a low-
pass filter to reduce output ripple of the VRMS output. Note
that a minimum of 4.7 nF capacitive load should be kept on the
RMS output.
To operate the device in peak-hold mode, the control line must be
temporally set to HI (reset or envelope mode) and then set back to
LO (peak-hold mode). This allows the ADL5502 to be initialize to
a known state.
EVALUATION BOARD
Figure 18 shows the schematic of the ADL5502 evaluation
board. The board is powered by a single supply in the 2.5 V to
3.5 V range. The power supply is decoupled by 100 pF and
0.1 μF capacitors. Table 4 details the various configuration
options of the evaluation board. Figure 19 and Figure 20 show
the component and circuit layouts of the evaluation board.
The RF input has a broadband match of 50 Ohms using a single
75 Ω resistor at R10. More precise matching at spot frequencies
is possible using the pads for components C15, C16, and R10.
The two outputs, accessible via the SMAs labeled VRMS and
VENV, provide the rms response and the envelope/peak-hold
vmeasurement of the RF input power level. The device must be
enabled by switching SW1 to HI (setting the switch to the
position opposite that of the “SW1” label).
Rev. PrD (04/20/2008) | Page 10 of 14
The device is place in peak-hold mode by placing switch SW2 in
the position closes to the “SW2” label. Envelope-tracking mode is
possible by setting SW2 in the opposite switch position (away from
the “SW2” label). A signal generator can drive the control mode
via the SMA labeled CNTL (see Table 4 for more details).
OPERATING IN PEAK-HOLD MODE
To operate the device in peak-hold mode, the control line must be
temporally set to HI (envelope mode) and then set back to LO
(peak-hold mode). This allows the ADL5502 to be initialize to a
known state.
For envelope mode or rms use only, the control line can simply be
set to HI.
Figure 17. Basic Connections for ADL5502
Preliminary Technical Data