MAX2016_06 Datasheet, PDF (13/20 Pages) Maxim Integrated Products – LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements

LF-to-2.5GHz Dual Logarithmic Detector/
Controller for Power, Gain, and VSWR Measurements
20kΩ
MAX2016
RFINA LOGARITHMIC
DETECTOR
RFINB _LOGARITHMIC
DETECTOR
RF BLOCK
COUPLER
IN
COUPLER
OUT
SETD
OUTD
GND
OUTD
Figure 3. Gain Measurement Configuration
Measuring Gain
The MAX2016 can be used to measure the gain of an
RF block (or combination of blocks) through the imple-
mentation outlined in Figure 3. As shown, a coupled
signal from the input of the block is fed into RFINA,
while the coupled output is connected to RFINB. The
DC output voltage at OUTD is proportional to the power
difference (i.e., gain).
The gain of a complete receiver or transmitter lineup
can likewise be measured since the MAX2016 accepts
RF signals that range from low frequency to 2.5GHz;
see Figure 4. The MAX2016 accurately measures the
gain, regardless of the different frequencies present
within superheterodyne architectures.
For accurate measurement of signals carrying signifi-
cant amplitude modulation, limit the bandwidth of the
difference amplifier to be less than the lowest modula-
tion frequency. This will minimize the ripple in the
OUTD waveform. This is particularly appropriate if the
system-level time delay between the two sense points
is significant with respect to the period of modulation.
f_RF
COUPLER
LNA
MIXER
LO
f_IF
COUPLER
RFINA LOGARITHMIC
DETECTOR
LOGARITHMIC RFINB
DETECTOR
MAX2016
20kΩ
OUTD
OUT
SETD
Figure 4. Conversion Gain Measurement Configuration
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