MAX2091 MAXIM [Maxim Integrated Products], MAX2091 Datasheet - Page 25

• Manufacturer Part Number: MAX2091
• Description: 50MHz to 500MHz Analog VGA, 1735MHz to 1935MHz Upconverting Mixer with Image Filtering, Threshold Alarm Circuit, and Error Amplifier for Level Control
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 1. Cascaded IF-RF Lineup Using the MAX2091 and MAX2092
Closed-ALC mode operation consists of setting CTRL1
= CTRL2 = logic 1. The voltage on PLVLSET is set
externally to provide -3dBm at RF_OUT for IF_IN power
between -25dBm and +5dBm. For other input power
ranges, PLVLSET can be externally driven to any DC
value between 0 and 2.5V, such that the desired output
power is present at RF_OUT (see the
Circuit). An error amplifier compares the external detec-
tor’s voltage to that of PLVLSET, and drives the IF attenu-
ator in servo fashion until the error amplifier’s differential
input error voltage is near zero. The servo loop acts to
maintain the input power level to the mixer as the power
level at IF_IN changes. Ideally, a detector with an output
voltage range of 0.1V to 2.4V DC is recommended, but
the MAX2091 can operate with any detector whose out-
put ranges from 0 to 2.5V DC (with the coupling network
at IF_OUT already taken into account).
When used in conjunction with the MAX2092 RF VGA, a
nominal RF signal level of approximately -3dBm output
from the MAX2091 is recommended. With this specific
level setting, the complete MAX2091 and MAX2092 cas-
cade can yield a constant RF output power of at least
-20.5dBm to +5dBm over an IF input power range of
50MHz to 500MHz Analog VGA, 1735MHz to 1935MHz
TO +5dBm
-25dBm
Upconverting Mixer with Image Filtering, Threshold
IF_IN
Alarm Circuit, and Error Amplifier for Level Control
(ANALOG CONTROL)
IF PLVLSET
38dB
Closed-ALC Mode Operation
MAX2091
2.5dB PAD
INPUT FROM
EXTERNAL
DETECTOR
Typical Application
THRESHOLD
ALARM
LO
IF
ALARM
OUT
-25dBm to +5dBm. See
the factory for additional details surrounding Maxim’s
MAX2091 and MAX2092 reference design.
The MAX2091 has four control inputs: CTRL1, CTRL2,
ALM_THRES, and PLVLSET. VCC must be present
before voltages are applied to these pins. In cases where
this is not possible, a 200I resistor must be included in
series with the control inputs to limit on-chip ESD diode
conduction. CTRL1 and CTRL2 are 3V logic controls and
cannot be driven from 5V logic. In the case where no
logic control is available and a logic-high is required, a
voltage-divider can be used from the 5V VCC supply to
produce the 3V logic-high.
As shown in
provisions have been made to allow for the placement of
a Tee attenuator between the VGA output and the mixer
input. A default value of 2.5dB is used within the applica-
tion circuit, although any desired value can be chosen.
Alternatively, the attenuator can be replaced by a sim-
ple equalizer circuit if additional frequency gain-slope
correction is desired over wider bands of operation.
(ANALOG CONTROL)
RF PLVLSET
40dB
Figure 1
and the
FROM EXTERNAL
THRESHOLDS
MAX2092
DETECTOR
Figure 1
INPUT
Typical Application
ALARM
MAX2091
VGA Output Pad
for details. Contact
C ontrol Inputs
RF_OUT
-20.5dBm
TO +5dBm
RF
ALARM
OUT
Circuit,
25