Datasheet
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MAX2090
50MHz to 1000MHz Analog VGA and Power
Detector with Optional AGC Loop
Detailed Description
The MAX2090 is a high-linearity analog VGA designed
to interface with 50I systems operating in the 50MHz
to 1000MHz frequency range. Either the on-board RMS
power detector or an external analog control voltage con-
trols the analog attenuator. The device features a gain
range of -11.5dB to +25.5dB, a noise figure of 4dB, OIP3
linearity of +38dBm, and a wide RF bandwidth. Each of
these features makes the device an ideal VGA for numer-
ous receiver and transmitter applications. In addition, the
device operates from a single +5.0V supply.
Applications Information
Modes of Operation
The device can operate in several different modes, as
summarized in Table 1.
VGA-Only Mode Operation
VGA-only mode operation consists of setting CTRL1 =
logic 1 and CTRL2 = logic 0, and applying a DC value to
PLVLSET between 0 and 2.5V DC to manually adjust the
attenuator and subsequently the RF_OUT power to any
desired value. The output power at RF_OUT increases at
a rate of 19.5dB/V as PLVLSET is increased. The power
detector is powered off in this mode, reducing the supply
current (10mA typ) from the case where the detector is
powered on. In VGA-only mode, components R2–R5 and
C6–C9 can be left unpopulated.
Closed-ALC Mode Operation
Closed-ALC mode operation consists of setting CTRL1 =
CTRL2 = logic 1. The voltage on PLVLSET is set exter-
nally to 1.65V (typ), providing -3dBm at DET_IN for RF_IN
power between -30dBm and +8dBm. For other input
power ranges, PLVLSET can be externally driven to a DC
Pin Description (continued)
Table 1. Mode Control Logic
PIN NAME FUNCTION
12 ALM
Alarm Logic Output. The output is high when the RF_IN power is above the alarm threshold. The
output is low when the RF_IN power is below the alarm threshold. The alarm threshold is set by
the ALM_THRES pin. See the Alarm Operation section for details.
16 ALM_THRES Alarm Threshold Voltage Input. See the Alarm Operation section for operation details.
17 CTRL1 Functional Control Bit (see Table 1)
18 DET_IN Power Detector Input. See the Typical Application Circuit for connection details.
19 RF_OUT
RF Output (50I). See the Typical Application Circuit for connection details.
20 V
CC_RF
Driver Amplifier Supply Voltage Input. Bypass to ground with a 10nF capacitor as close as pos-
sible to the pin.
— EP
Expose Pad. Internally connected to ground. Connect to GND for proper RF performance and
enhanced thermal dissipation.
CTRL1 CTRL2 VGA
RMS
DETECTOR
ALC LOOP ALARM FUNCTION DESCRIPTION
0 0 Disabled Disabled Disabled Low Power-down mode
0 1 Enabled Enabled Disabled Enabled
Open-ALC mode: PLVLSET directly
controls VGA and detector output voltage
is available on DET_VOUT
1 0 Enabled Disabled Disabled Low VGA-only mode
1 1 Enabled Enabled Enabled Enabled
Closed-ALC mode: ALC loop locks
DET_VOUT to PLVLSET