1. For best results at 2.4 GHz, use 8 pF 0402 profile SMT capaci-
tors on RF ports and 100 pF bypassing on pins 4 and 6.
Description
The SW-438 is a GaAs MMIC SPDT switch in a low cost
SOT-363 surface mount plastic package. Typical applications include transmit/receive switching for Bluetooth and
WLAN equipment. The SW-438 can also be used in applications up to 500 mW in systems such as cellular, PCS,
DCS1800, GSM, CDMA and other analog and digital wireless communications systems.
M/A-COM fabricates the SW-438 using a 0.5 micron gate
length GaAs p-HEMT process. The process features full pa ssivation for increased performance and reliability.
External Component Requirements
Please note the values of the external capacitors. The capacitors at each of the RF ports are used as for achieving
optimum insertion loss. They also provide DC blocking for
positive control. The 8 pF (0402) capacitor is recommendedfor 2 - 3 GHz operation. If this value is changed or
the capacitor placed too far from the switch, theperformance will be affected. We also recommend 100 pF bypass
capacitors on pins 4 and 6.
For broadband applications with positive control voltages,
use DC blocking capacitors with value of 39 pF or more.
Functional Schematic
C=100pF
V1 RFC V2
RF1 GND RF2
PIN 1
2.4 GHz Application
C=8pFC=8pF
C=8pF
C=100pF
C=100pF
V1 RFC V2
RF1 GND RF2
PIN 1
C≥39pFC≥39pF
C≥39pF
Broad Band Applications
Pin Configuration
Pin No. Function Description
1 RF1 RF Input/Output
2 GND RF Ground
3 RF2 RF Input/Output
4 V2 Control 2 Input
5 RFC RF Common Port
6 V1 Control 1 Input
Ordering Information
Part Number Package
SW-438TR-3000 SW-438 on 13 Inch, 3000 piece Reel
C=100pF
SW-438SMB SW-438 sample test board
Truth Table
Mode
(Control)
Positive1 0 + 0.2V
Negative 2 0 + 0.2V
1.External DC blocking capacitors are required on all RF ports.
2.If negative control is used, DC blocking capacitors are not required on RF ports.