MAX2015 Maxim, MAX2015 Datasheet - Page 8

• Manufacturer Part Number: MAX2015
• Description: The MAX2015 complete multistage logarithmic amplifier is designed to accurately convert radio-frequency (RF) signal power in the 0
• Manufacturer: Maxim

The MAX2015 is a successive detection logarithmic
amplifier designed for use in RF power measurement
and AGC applications with a 0.1GHz to 3GHz
frequency range from a single 2.7V to 3.6V power
supply. It is pin compatible with other leading logarith-
mic amplifiers.
The MAX2015 provides for improved performance with a
high 75dB dynamic range at 100MHz, and exceptional
accuracy over the extended temperature range and sup-
ply voltage range.
The MAX2015 differential RF input (INHI, INLO) allows
for broadband signals between 100MHz and 3GHz. For
single-ended signals, AC-couple INLO to ground. The
RF inputs are internally biased and need to be AC-cou-
pled using 680pF capacitors as shown in Figure 1 and
Figure 2. An internal 50Ω resistor between INHI and
INLO provides a good 50MHz to 3.0GHz match.
The SET input is used for loop control when in controller
mode or to set the slope of the output signal (mV/dB)
when in detector mode. The internal input structure of
SET is two series 20kΩ resistors connected to ground.
The center node of the resistors is fed to the negative
input of the internal output op amp.
The MAX2015 requires power-supply bypass capacitors
connected close to each V
connect a 0.1µF capacitor (C4, C6) and a 100pF capac-
itor (C3, C5) with the 100pF capacitor being closest to
the pin.
For power-supply voltages (V
set R4 = 0Ω (see the typical applications circuits).
For power-supply voltages (V
5.25V, set R4 = 75Ω ±1% (100ppm/°C max) and PWDN
must be connected to GND.
The MAX2015 can be powered down by driving PWDN
with logic high (logic high = V
mode, the supply current is reduced to a typical value
of 1µA. For normal operation, drive PWDN with a logic
low. It is recommended when using power-down that
an RF signal not be applied before the power-down
signal is low.
0.1GHz to 3GHz, 75dB Logarithmic
Detector/Controller
8
_______________________________________________________________________________________
Power-Supply Connections
Detailed Description
CC
S
) between 2.7V and 3.6V,
Power-Down Mode
S
pin. At each V
) between 4.75V and
CC
). In power-down
SET Input
RF Input
CC
pin,
In detector mode, the MAX2015 acts like an RSSI,
which provides an output voltage proportional to the
input power. This is accomplished by providing a feed-
back path from OUT to SET (R1 = 0Ω; see Figure 1).
By connecting SET directly to OUT, the op amp gain is
set to 2V/V due to two internal 20kΩ feedback resistors.
This provides a detector slope of approximately
18mV/dB with a 0.5V to 1.8V output range.
The MAX2015 can also be used as a detector/controller
within an AGC loop. Figure 3 depicts one scenario
where the MAX2015 is employed as the controller for a
variable-gain PA. As shown in the figure, the MAX2015
monitors the output of the PA through a directional cou-
pler. An internal integrator (Figure 2) compares the
Table 1. Suggested Components of
Typical Applications Circuits
Figure 1. Detector-Mode (RSSI) Typical Application Circuit
*RSSI mode only.
**V
DESIGNATION
S
V
S
= 2.7V to 3.6V.
R4
RFIN
C1, C2
C3, C5
C4, C6
C6
C4
R4**
R1*
C5
C3
C1
C2
Applications Information
1
2
3
4
V
INHI
INLO
V
VALUE
680pF
100pF
CC
CC
0.1µF
DETECTORS
0Ω
0Ω
MAX2015
Detector (RSSI) Mode
20kΩ
0603 ceramic capacitors
0603 ceramic capacitors
0603 ceramic capacitors
0603 resistor
0603 resistor
20kΩ
Controller Mode
PWDN
GND
OUT
SET
8
7
6
5
TYPE
R1
OUT