ADL5902-EVALZ AD [Analog Devices], ADL5902-EVALZ Datasheet - Page 19

• Manufacturer Part Number: ADL5902-EVALZ
• Description: 50 MHz to 9 GHz 65 dB TruPwr Detector
• Manufacturer: AD [Analog Devices]

calculated by the linear-regression fit over the linear range of
the detector, typically at 25°C. The error in decibels is calculated
by
where P
1 milliwatt (the input amplitude that would produce a 0 V output
if such an output were possible).
The error from the ideal line is not a measure of absolute accuracy
because it is calculated using the slope and intercept of each
device. However, it verifies the linearity and the effect of
temperature and modulation on the response of the device. An
example of this type of plot is Figure 3. The slope and intercept
that form the ideal line are those at 25°C with CW modulation.
Figure 21 and Figure 24 show the error with various popular
forms of modulation with respect to the ideal CW line. This
method for calculating error is accurate, assuming that each
device is calibrated at room temperature.
In the second plot format, the V
amplitude and temperature is subtracted from the corresponding
V
error in decibels. This type of plot does not provide any
information on the linear-in-dB performance of the device; it
merely shows the decibel equivalent of the deviation of V
over temperature, given a calibration at 25°C. When calculating
error from any one particular calibration point, this error
format is accurate. It is accurate over the full range shown on
the plot assuming that enough calibration points are used.
Figure 6 shows this plot type.
OUT
Error (dB) = (V
at 25°C and then divided by the 25°C slope to obtain an
Z
is the x-axis intercept expressed in decibels relative to
OUT
− Slope × (P
RFIN
60.4Ω
OUT
R3
voltage at a given input
IN
100pF
C10
− P
INLO
Z
C12
100pF
Figure 45. Basic Connections for Operation in Measurement Mode
INHI
))/Slope
NC
NC
NC
(SEE TABLE 4)
14
15
16
13
2
TADJ/PWDN
ADL5902
(NEGATIVE SLOPE)
BIAS AND POWER-
LINEAR-IN-dB VGA
DOWN CONTROL
R12
100pF
0.1µF
C3
C4
1
OUT
TABLE 4)
VPOS
(SEE
R9
(15)
Rev. 0 | Page 19 of 28
5V
3
VREF
VREF
2.3V
11
POS
3.74kΩ
R10
VTGT
X
X
5V
10
2
2
12
I
I
The error calculations for Figure 30 are similar to those for the
V
temperature are determined and applied as follows:
where:
T
temperature that would result in a V
possible).
Temp is the ambient temperature of the ADL5902 in degrees
Celsius.
Slope is, typically, 4.9 mV/°C.
V
MEASUREMENT MODE BASIC CONNECTIONS
The ADL5902 requires a single supply of nominally 5 V. The
supply is connected to the two VPOS supply pins. These pins
should each be decoupled using the two capacitors with values
equal or similar to those shown in Figure 45. These capacitors
should be placed as close as possible to the VPOS pins.
An external 60.4 Ω resistor combines with the relatively high RF
input impedance of the ADL5902 to provide a broadband 50 Ω
match. An ac coupling capacitor should be placed between this
resistor and INHI. The INLO input should be ac-coupled to
ground using the same value capacitor. Because the ADL5902
has a minimum input operating frequency of 50 MHz, 100 pF
ac coupling capacitors can be used.
The ADL5902 is placed in measurement mode by connecting
VOUT to VSET. In measurement mode, the output voltage is
proportional to the log of the rms input signal level.
DET
TGT
R11
2kΩ
Z
TEMP
OUT
100pF
0.1µF
TEMPERATURE
is the x-axis intercept expressed in degrees Celsius (the
C7
C5
Error (°C) = (V
SENSOR
COMM
plots. The slope and intercept of the V
is the voltage at the TEMP pin at that temperature.
9
G = 5
26pF
COMM
4
8
7
6
5
VSET
VOUT
CLPF
TEMP
TEMP
C9
10µF
(SEE THE
CHOOSING A
VALUE FOR
C
− Slope × (Temp − T
LPF
VOUT
SECTION.)
TEMP
of 0 V if this were
TEMP
Z
))/Slope
function vs.
ADL5902
(16)