20
Maxim Integrated
MAX19792
500MHz to 4000MHz Dual Analog Voltage Variable 
Attenuator with On-Chip 10-Bit SPI-Controlled DAC
Table 7. Typical Application Circuit 
Component Values
Layout Considerations
A properly designed PCB is an essential part of any RF/
microwave circuit. Keep RF signal lines as short as pos-
sible to reduce losses, radiation, and inductance. For best 
performance, route the ground-pin traces directly to the 
exposed pad underneath the package. This pad MUST 
be connected to the ground plane of the board by using 
multiple vias under the device to provide the best RF and 
thermal conduction path. Solder the exposed pad on the 
bottom of the device package to a PCB. Pins 4 and 31 
for the MAX19792 have no internal connection. These two 
pins are in place to support the MAX19794 part in the fam-
ily. The MAX19794 requires an additional bypass capaci-
tor on each of these pins for proper operation. If desired 
to have a common layout to support the MAX19794, then 
include these capacitors in the common layout. Refer to 
the MAX19794 data sheet for details.
Power-Supply Bypassing
Proper  voltage-supply  bypassing  is  essential  for  high-
frequency  circuit  stability.  Bypass  each  V
CC
  pin  with 
capacitors placed as close as possible to the device. 
Place the smallest capacitor closest to the device. See 
the Typical Application Circuit and Table 7 for details.
Exposed Pad RF and   
Thermal Considerations
The exposed pad (EP) of the devices 36-pin TQFN pack-
age provides a low thermal-resistance path to the die. It 
is important that the PCB on which the IC is mounted be 
designed to conduct heat from this contact.
In  addition,  provide  the  EP  with  a  low-inductance  RF 
ground path for the device. The EP must be soldered to 
a ground plane on the PCB, either directly or through an 
array of plated via holes. Soldering the pad to ground is 
also critical for efficient heat transfer. Use a solid ground 
plane wherever possible.
*Add two additional 10I series resistors between V
CC
s lead-
ing to C5 and C6, unless a V
CC
 power plane is used.
DESIGNATION    QTY
DESCRIPTION
C1, C2, C4
3
22pF Q5%, 50V C0G ceramic 
capacitors (0402)
C3
1
22pF Q5%, 50V C0G ceramic 
capacitors (0402)
Not installed for two attenuators 
in cascade.
C5C9
5
1000pF Q5%, 50V C0G ceramic 
capacitors (0402)
C12
1
120pF Q5%, 50V C0G ceramic 
capacitor (0402)
Provides some external noise 
filtering along with R3.
C13
0
Not installed, 4.7pF capacitor
could be used to reduce any 
potential rise time glitching when 
the comparator changes state.
R1, R2
2
10I Q5% resistors* (0402)
R3
1
200I Q5% resistor (0402)
Use this resistor to provide some 
lowpass noise filtering when used 
with C12. The value of R3 slows 
down the response time. R3 also 
provides protection for the device 
in case V
CTRL
 is applied without 
V
CC
 present.
U1
1
Maxim MAX19792