max2014evkit Maxim Integrated Products, Inc., max2014evkit Datasheet - Page 9

• Manufacturer Part Number: max2014evkit
• Description: Max2014 50mhz To 1000mhz, 75db Logarithmic Detector/controller
• Manufacturer: Maxim Integrated Products, Inc.

The MAX2014 can also be used as a detector/controller
within an AGC loop. Figure 3 depicts one scenario
where the MAX2014 is employed as the controller for a
variable-gain PA. As shown in the figure, the MAX2014
monitors the output of the PA through a directional cou-
pler. An internal integrator (Figure 2) compares the
detected signal with a reference voltage determined by
V
es or decreases the voltage at OUT, according to how
closely the detected signal level matches the V
erence. The MAX2014 adjusts the power of the PA to a
level determined by the voltage applied to SET. With R1 =
0Ω, the controller mode slope is approximately
19mV/dB (RF = 100MHz).
As with any RF circuit, the layout of the MAX2014 circuit
affects the device’s performance. Use an abundant num-
ber of ground vias to minimize RF coupling. Place the
input capacitors (C1, C2) and the bypass capacitors
(C3–C6) as close to the IC as possible. Connect the
bypass capacitors to the ground plane with multiple vias.
Figure 2. Controller-Mode Typical Application Circuit
SET
V
. The integrator, acting like a comparator, increas-
S
RFIN
R4
C6
C4
C5
C3
C1
C2
_______________________________________________________________________________________
1
2
3
4
V
INHI
INLO
V
CC
CC
50MHz to 1000MHz, 75dB Logarithmic
DETECTORS
Layout Considerations
MAX2014
20kΩ
20kΩ
Controller Mode
PWDN
GND
OUT
SET
8
7
6
5
SET
V
V
OUT
SET
ref-
Figure 3. System Diagram for Automatic Gain-Control Loop
PROCESS: BiCMOS
TRANSMITTER
TOP VIEW
SET-POINT
Detector/Controller
DAC
POWER AMPLIFIER
OUT
SET
V
OUT
1
CC
8
GAIN-CONTROL INPUT
MAX2014
INHI
SET
7
2
TDFN
Pin Configuration
Chip Information
20kΩ
20kΩ
GND PWDN
INLO
6
3
MAX2014
LOGARITHMIC
DETECTOR
V
5
4
CC
IN
COUPLER
9