max2645eubt Maxim Integrated Products, Inc., max2645eubt Datasheet - Page 9

• Manufacturer Part Number: max2645eubt
• Description: Max2645 3.4ghz To 3.8ghz Sige Low-noise Amplifier/pa Predriver
• Manufacturer: Maxim Integrated Products, Inc.

The MAX2645 is a versatile amplifier with high-gain,
high-linearity, and low-noise performance—features that
make it suitable for use as an LNA, high-linearity/low-
noise amplifier, PA predriver, or LO buffer in the 3.4GHz
to 3.8GHz frequency range. See Figure 1, MAX2645
Typical Application Circuit, for recommended compo-
nent values. A single external bias-setting resistor allows
the system designer to trade off linearity for reduced
supply current. A logic-level control reduces gain by a
25dB step to further improve input IP3 performance. A
low-power shutdown mode disables the device and
reduces current consumption to 0.1µA.
The linearity and supply current of the MAX2645 are
externally programmable with a single resistor (R
placed from BIAS to GND. Larger resistor values result
in lower IP3 performance and lower supply current, while
smaller resistor values result in higher IP3 performance
and higher supply current. Use resistor values in the
15k
suitable for most applications. See Typical Operating
Characteristics for performance variation vs. R
value.
Table 1. MAX2645 S-Parameters
FREQ
(MHz)
3400
3450
3500
3550
3600
3650
3700
3750
3800
3400
3450
3500
3550
3600
3650
3700
3750
3800
to 25k
range, with a nominal value of 20k
_______________________________________________________________________________________
0.468
0.466
0.472
0.469
0.471
0.477
0.485
0.484
0.492
0.454
0.457
0.465
0.468
0.472
0.481
0.486
0.486
0.499
MAG
Detailed Description
S11
PHASE
-149.8
-150.4
-151.6
-153.4
-154.6
-155.0
-156.6
-156.5
-157.0
-146.6
-147.4
-147.9
-149.7
-150.5
-150.5
-152.2
-152.4
-152.6
Low-Noise Amplifier/PA Predriver
Bias Circuitry
R
R
BIAS
BIAS
5.061
4.975
5.098
4.883
4.814
5.118
4.769
4.780
4.939
5.350
5.245
5.375
5.165
5.066
5.386
5.040
5.019
5.207
MAG
= 20k , V
= 15k , V
BIAS
BIAS
S21
)
CC
CC
PHASE
-44.6
-46.3
-49.9
-53.7
-53.7
-57.4
-63.4
-62.3
-66.6
-41.8
-43.5
-46.6
-50.3
-50.2
-53.4
-59.4
-58.3
-62.0
= +3.3V, T
= +5V, T
The MAX2645 features a logic-level gain step control
input (GAIN) that places the device in high-gain or low-
gain mode. A logic-level high places the device in high-
gain mode, where the gain is 14.5dB. A logic-level low
places the device in low-gain/high-linearity mode, where
the gain is reduced to 10dB and the input IP3 perfor-
mance is increased.
The MAX2645 features a logic-level shutdown control
input. A logic high on SHDN enables the device for nor-
mal operation. A logic low on SHDN disables all device
functions and reduces supply current to 0.1µA.
The RFIN port is internally biased and requires an exter-
nal DC-blocking capacitor. A matching network is
required for best performance. Figure 1 shows compo-
nent values optimized for best noise-figure performance,
low-noise figure, high-input IP3 performance, and high-
output P1dB performance in the 3.4GHz to 3.8GHz fre-
quency range. For matching to other frequencies, see
Tables 1 and 2.
3.4GHz to 3.8GHz SiGe
A
A
= +25 C
= +25 C
0.053
0.058
0.056
0.054
0.056
0.058
0.054
0.058
0.060
0.057
0.061
0.060
0.057
0.060
0.063
0.060
0.062
0.065
MAG
S12
Applications Information
PHASE
-55.5
-60.8
-64.6
-62.7
-64.4
-68.9
-70.5
-72.0
-75.4
-51.3
-56.7
-61.2
-61.0
-62.7
-67.6
-67.8
-67.0
-73.3
Shutdown Control
Gain Step Control
0.660
0.658
0.661
0.658
0.647
0.657
0.657
0.654
0.654
0.651
0.646
0.654
0.652
0.645
0.652
0.648
0.642
0.643
MAG
S22
RF Input
PHASE
-57.0
-58.4
-60.6
-63.0
-64.2
-66.2
-69.8
-70.9
-72.3
-52.3
-53.7
-55.6
-58.3
-59.3
-60.7
-63.9
-64.8
-66.2
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