Typical application circuit, Exposed pad rf/thermal considerations – Rainbow Electronics MAX19998 User Manual
Page 27
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
MAX19998
______________________________________________________________________________________ 27
Typical Application Circuit
Exposed Pad RF/Thermal Considerations
The exposed pad (EP) of the MAX19998’s 20-pin thin
QFN-EP package provides a low thermal-resistance
path to the die. It is important that the PCB on which
the MAX19998 is mounted be designed to conduct
heat from the EP. In addition, provide the EP with a low-
inductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PCB, either directly or
through an array of plated via holes.
NOTE: PINS 4, 5, 10, 12, AND 17 ARE ALL INTERNALLY
CONNECTED TO THE EXPOSED GROUND PAD. CONNECT
THESE PINS TO GROUND TO IMPROVE ISOLATION.
*C16 NOT USED FOR 3000MHz TO 4000MHz APPLICATIONS.
PINS 3, 9, 13, AND 15 HAVE NO INTERNAL CONNECTION, BUT CAN BE
EXTERNALLY GROUNDED TO IMPROVE ISOLATION.
MAX19998
U1
19
20
18
17
7
6
8
RF
GND
GND
9
V
CC
1
2
4
5
15
14
12
11
LOBIA
S
V
CC
GND
GN
D
GND
3
13
16
10
V
CC
V
CC
GND
GND
LO
IF+
IF-
GND
LEXT
IFBIAS
EP
L1
L2
L3
C13
R3
R2
R1
C15
C10
C8
C9
C11
+5.0V
+5.0V
LO
INPUT
C6
C1
RF
INPUT
+5.0V
4:1
IF
OUTPUT
T1
3
2
6
1
4
C14
C3
C2
C16*
+5.0V
GND