Data Sheet

ADG904/ADG904-R

Rev. C | Page 11 of 16

APPLICATIONS

The ADG904 and ADG904-R are ideal solutions for low power,

high frequency applications. The low insertion loss, high

isolation between ports, low distortion, and low current

consumption of these parts make them excellent solutions for

many high frequency switching applications. They may be used

in applications such as switchable filters, transmitters and

receivers for radar systems, and communications systems from

base stations to cell phones.

The ADG9xx wideband switches are designed to meet the

demands of devices that transmit at ISM band frequencies of

1 GHz and higher. The low insertion loss, high isolation

between ports, single pin control interface, no requirement for

dc blocking capacitors, and TTL interface compatibility of these

parts make them cost-effective and an easy-to-integrate

switching solution for many high frequency switching

applications and low power applications where the parts can

handle up to 16 dBm of power.

ABSORPTIVE VS. REFLECTIVE

The ADG904 is an absorptive (matched) switch with 50 Ω

terminated shunt legs; the ADG904-R is a reflective switch with

0 Ω terminated shunts to ground. The ADG904 absorptive

switch has a good VSWR on each port, regardless of the switch

mode. An absorptive switch should be used when there is a

need for a good VSWR that is looking into the port but not

passing the through signal to the common port. The ADG904 is

therefore ideal for applications that require minimum

reflections back to the RF source. It also ensures that the

maximum power is transferred to the load.

The ADG904-R reflective switch is suitable for applications

where high off port VSWR does not matter, and the switch has

other performance features. It may be used in many applica-

tions, including high speed filter selection. In most cases, an

absorptive switch may be used instead of a reflective switch, but

not vice versa.

ANTENNA DIVERSITY SWITCH

The ADG904 is ideal for use as an antenna diversity switch,

switching different antennas into the tuner. The low insertion

loss ensures minimum signal loss and high isolation between

channels, making these SP4T switches suitable for switching

applications in tuner modules and set-top boxes.

TUNER

ADG904

CABLE

RF1

RF2

RF3

RF4

VGA

ANTENNA

Figure 27. Tuner Modules

FILTER SELECTION

The ADG904 can be used to switch high frequency signals

between different filters and to multiplex the signal to the

output. These SP4T switches are also ideal for high speed

signal routing.

RFC

ADG904

ADG904

RF1

RF2

RF3

RF4

RF1

RF2

RF3

RF4

RFC

Figure 28. Filter Selection

Tx/Rx SWITCHING

The low insertion loss and high isolation between ports ensure

that the ADG904 and ADG904-R are suitable transmit/receive

switches for all ISM band and wireless LAN, providing the

required isolation between the transmit signal and the

receive signal.

ADG904

Tx

Rx

Rx

Rx

Rx

ANTENNA

Figure 29. Tx/Rx Switching