
M
RF Power Detector
_______________________________________________________________________________________
5
Pin Description
PIN
1
2
3
4
5
NAME
V
CC
GND
RFIN
ENA
OUT
FUNCTION
Power-Supply Pin. Bypass to GND with a capacitor as close as possible to the pin.
Ground Connection. Use multiple ground vias to connect the GND pin to the ground plane.
RF Input. AC-couple with an external capacitor.
Enable Input. Drive low to turn the part off. Drive high or connect to V
CC
to turn the part on.
Power Detector Output. Filter with a capacitor to GND.
Detailed Description
The MAX2204 RF power detector is designed to operate
from 450MHz to 2.5GHz. The device accepts an RF
signal at the input and outputs a highly repeatable volt-
age, which increases monotonically with increasing
input power. See the Typical Operating Characteristics
The device is designed to compensate for temperature
and process shifts, reducing the typical output variation
to less than ±0.5dB at full input power and ±1.5dB at
the lower power.
The MAX2204 features a detection range from -16dBm
to +5dBm. High input impedance allows a for low-loss
resistive tap if an isolator is used. The device uses
external termination at the input so that the RF signal
from several directional couplers can be connected to
a single detector chip.
The MAX2204 features an enable input (ENA) that
allows the device to be put in shutdown. For normal
operation, drive ENA high or connect to V
CC
. For
device shutdown, drive ENA low.
The MAX2204 integrates an output series resistor of
approximately 100k
. For output filtering, connect only
a capacitor to ground at the output.
Applications Information
The MAX2204 uses external termination when using
directional couplers. See Figure 1 for the typical appli-
cation circuit. The output of the detector is typically
connected to an ADC in cdma2000 or WCDMA power-
control topology.
PEAK
DETECT
BUFFER
PA 1
PA 1
PA 2
COUPLER 1
COUPLER 1
COUPLER 2
BIAS
DETECTOR
OUTPUT
10
10
50
50
50
50
ENABLE
ENABLE
PEAK
DETECT
BUFFER
BIAS
DETECTOR
OUTPUT
MAX2204
MAX2204
APPLICATION DIAGRAM FOR ONE PA
APPLICATION DIAGRAM FOR TWO PAs
Figure 1. Typical Application Circuit