max2645eubt Maxim Integrated Products, Inc., max2645eubt Datasheet - Page 10

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

3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
The RFOUT port is an open-collector output that must be
tied to V
The MAX2645 EV kit uses a length of transmission line
equivalent to 1.5nH of inductance. A DC-blocking
capacitor is required and can be part of the output
matching network. See Figure 1 for component values
recommended for operation over the 3.4GHz to 3.8GHz
frequency range. See Table 1 for matching to other fre-
quencies. This transmission line is terminated at the
V
ing. This arrangement provides a high-Q, low-loss bias
network used to optimize performance. The radial stub
can be replaced with an appropriate microwave
capacitor.
Proper power-supply bypassing is essential for high-fre-
quency circuit stability. Bypass V
and 50pF capacitors located as close to the V
possible.
10
Table 2. MAX2645 Noise Parameters
CC
FREQUENCY (MHz)
______________________________________________________________________________________
node with a radial stub for high-frequency bypass-
Power-Supply, Bias Circuitry, and Logic-
CC
3400
3450
3500
3550
3600
3650
3700
3750
3800
3400
3450
3500
3550
3600
3650
3700
3750
3800
through an inductance for proper biasing.
F MIN (dB)
2.103
2.127
2.152
2.177
2.203
2.229
2.256
2.282
2.310
2.098
2.122
2.148
2.173
2.198
2.225
2.251
2.279
2.306
CC
Input Bypassing
with 10µF, 0.1µF,
R
R
BIAS
BIAS
RF Output
CC
= 20k , V
= 15k , V
pin as
CC
0.237
0.235
0.235
0.234
0.233
0.232
0.231
0.230
0.229
CC
0.210
0.209
0.208
0.207
0.206
0.206
0.205
0.204
0.204
| opt |
= +3.3V, T
= +5V, T
To minimize the amount of noise injected into the bias
circuitry and logic inputs, bypass the pins with capaci-
tors located as near to the device pin as possible. For
additional isolation on the logic-control pins, place resis-
tors between the logic-control inputs and the bypass
capacitors. See Figure 1 for recommended component
values; refer to MAX2645 EV kit manual for recommend-
ed board layout.
A properly designed PC board is an essential part of any
RF/microwave circuit. Keep RF signal lines as short as
possible to reduce losses, radiation, and inductance.
Use separate, low-inductance vias to the ground plane
for each ground pin. For best performance, solder the
exposed paddle on the bottom of the device package
evenly to the board ground plane.
A
A
= +25 C
= +25 C
opt ANGLE
146.3
148.4
150.5
152.6
154.7
156.8
158.9
161.0
163.1
144.1
146.1
148.2
150.3
152.4
154.5
156.5
158.6
160.7
Layout Considerations
R N ( )
31.1
31.5
32.0
32.5
32.9
33.5
33.9
34.5
35.0
31.1
31.6
32.1
32.5
33.0
33.5
34.0
34.6
35.1