AD8313_04 Datasheet, PDF (22/24 Pages) Analog Devices – 0.1 GHz to 2.5 GHz 70 dB Logarithmic Detector/Controller

AD8313
V_PS1
INHI
INLO
V_PS1
R1
10Ω
C1
680pF
C2
680pF
R9
0Ω _R2
10Ω
R2
10 Ω
Z1
C3
0.1µF
L/R
53.6Ω
1 VPOS VOUT 8
AD8313
2 INHI VSET 7
3 INLO COMM 6
4 VPOS PWDN 5
C4
0.1µF
V_NEG
C7 ^R4
0.1µF ^0Ω
R12
301Ω
R10
OPEN
R5
TP1
0Ω
Z2
R11
0Ω
AD8009 R7
0Ω
C5
0.1µF _R3
0Ω
R8
20kΩ
R6
OPEN
C6
OPEN
VOUT
EXT VSET
V_PS2
SW1 B
A
EXT ENABLE
Figure 44. Evaluation Board Schematic
Table 7. Evaluation Board Configuration Options
Component
Function
VPS1, VPS2,
GND, VNEG
Z1
Z1
SW1
R7, R8
L/R, C1, C2, R9
R10, R12
Supply Pins. VPS1 is the positive supply pin for the AD8313. VPS2 and VNEG are the
positive and negative supply pins for the AD8009. If the AD8009 is being operated
from a single supply, VNEG should be connected to GND. VPS1 and VPS2 are
independent. GND is shared by both devices.
AD8313 Logarithmic Amplifier. If the AD8313 is used in measurement mode, it is not
necessary to power up the AD8009 op amp. The log output can be measured at TP1 or
at the SMA connector labeled VSET.
AD8009 Operational Amplifier.
Device Enable. When in Position A, the PWDN pin is connected to ground and the
AD8313 is in normal operating mode. In Position B, the PWDN pin is connected to an
SMA connector labeled ENBL. A signal can be applied to this connector.
Slope Adjust. The slope of the AD8313 can be increased from its nominal value of
18 mV/dB to a maximum of 40 mV/dB by removing R11, the 0 Ω resistor, which shorts
VSET to VOUT, and installing a 0 Ω resistor at R7. The 20 kΩ potentiometer at R8 can
then be used to change the slope.
Operating in Controller Mode. To put the AD8313 into controller mode, R7 and R11
should be removed, breaking the link between VOUT and VSET. The VSET pin can then
be driven externally via the SMA connector labeled VSET.
Input Interface. The 52.3 Ω resistor in position L/R, along with C1 and C2, create a
wideband 50 Ω input. Alternatively, the 52.3 Ω resistor can be replaced by an inductor
to form an input matching network. See Input Coupling section for more details.
Remove the 0 Ω resistor at R9 for differential drive applications.
Op Amp Gain Adjust. The AD8009 is initially configured as a buffer; gain = 1. To increase
the gain of the op amp, modify the resistor values R10 and R12.
R5, R6, C6
R1, R2, R3, R4,
C3, C4, C5, C7
Op Amp Output Loading/Filtering. A variety of loading and filtering options are
available for the AD8009. The robust output of the op amp is capable of driving low
impedances such as 50 Ω or 75 Ω, configure R5 and R6 accordingly. See the AD8009
data sheet for more details.
Supply Decoupling.
Default
Not Applicable
Installed
Installed
SW1 = A
R7 = 0 Ω (Size 0603)
R8 = installed
L/R = 53.6 Ω (Size 0603)
C1 = C2 = 680 pF (Size 0603)
R9 = 0 Ω (Size 0603)
R10 = open (Size 0603)
R12 = 301 Ω (Size 0603)
R5 = 0 Ω (Size 0603)
R6 = open (Size 0603)
C6 = open (Size 0603)
R1 = R2 = 10 Ω (Size 0603)
R3 = R4 = 0 Ω (Size 0603)
C3 = C4 = 0.1 µF (Size 0603)
C5 = C7 = 0.1 µF (Size 0603)
Rev. D | Page 22 of 24