Data Sheet

ADRF5515A

APPLICATIONS INFORMATION

analog.com

Rev. 0 | 14 of 15

To generate the evaluation PCB used in a typical application circuit,

use proper RF circuit design techniques. Signal lines at the RF port

must have a 50 Ω impedance, and the package ground leads and

the backside ground slug must connect directly to the ground plane.

Use 300 Ω series resistors on the BP-CHx and PD-CHAB digital

control pins for glitch and overcurrent protection.

It is possible to tune the ADRF5515A to obtain better return loss

between 3.3 GHz to 3.8 GHz or 3.7 GHz to 4.2 GHz frequency

bands. An additional low impedance RF trace at the TERM-CHx pin

and a shunt capacitor at the ANT-CHx pin allows better return loss

for receive high gain mode, receive low gain mode and transmit

mode at the same time. It is possible to switch frequency bands by

adding/removing the shunt capacitor at the ANT-CHx pin. When the

shunt capacitor at the ANT-CHx pin is mounted, the device is tuned

to the 3.3 GHz to 3.8 GHz frequency band (low band). When the

capacitor is not mounted, the device is tuned to the 3.7 GHz to 4.2

GHz frequency band (high band).

Figure 27. External Matching Topology

The details of the external tuning network can be found in Table

8 and Figure 27. RF trace characteristic impedance and electrical

length can be applied to any different substrate of choice. Also in

Table 8, dimensions for an example grounded coplanar waveguide

implementation with 10 mil Rogers 4350 is shown.

Table 8. Matching Components

Matching Components

ANT-CHx Pin

TERM-CHx Pin

Series RF Trace

λ/20 at 3.6

 GHz

λ/4 at 3.6

 GHz

Width = 18 mil

Width = 26 mil

Gap = 13 mil

Gap = 13 mil

Length = 100 mil

Length = 500 mil

Shunt Capacitor

Capacitor = 0.3 pF

Not applicable

Low band tuning

Capacitor = do not

insert (DNI)

High band tuning

Simulated return losses for receive high gain mode, receive low

gain mode, and transmit mode are seen in Figure 28 and Figure 29.

For high gain mode, the return loss is better than 15 dB, and for low

gain mode, the return loss is better than 14 dB. For transmit mode,

the return loss is better than 18 dB.

Figure 28. ANT-CHx Return Loss at Receive High Gain and Receive Low Gain

Mode for Low Band and High Band Tuning

Figure 29. ANT-CHx and TERM-CHx Return Loss at Transmit Mode Compared

with and Without External Tuning