Data Sheet

ADRF5515A

THEORY OF OPERATION

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Rev. 0 | 13 of 15

The ADRF5515A requires a positive supply voltage applied to the

VDD1-CHA pin, VDD2-CHA pin, VDD1-CHB pin, VDD2-CHB pin,

and SWVDD-CHAB pin. Use bypassing capacitors on the supply

lines to filter noise.

SIGNAL PATH SELECT

The ADRF5515A supports transmit operations when 5 V is applied

to SWCTRL-CHAB. In transmit operation, when an RF input is

applied to ANT-CHA and ANT-CHB, the signal paths are connected

from ANT-CHA to TERM-CHA and from ANT‑CHB to TERM-CHB.

The ADRF5515A supports receive operations when 0 V is applied

to SWCTRL-CHAB. In receive operation, an RF input applied at

ANT-CHA and ANT-CHB connects ANT-CHA to RXOUT-CHA and

ANT-CHB to RXOUT-CHB.

Receive Operation

The ADRF5515A supports high gain mode, low gain mode, power-

down high isolation mode, and power-down low isolation mode in

receive operation, as detailed in Table 7.

When 0 V is applied to PD-CHAB, the LNA is powered up and the

user can select high gain mode or low gain mode. To select high

gain mode, apply 0 V to BP-CHA or BP-CHB. To select low gain

mode, apply 5 V to BP-CHA or BP-CHB.

When 5 V is applied to PD-CHAB, the ADRF5515A enters power-

down mode. To select power-down high isolation mode, apply 0 V

to BP-CHA or BP-CHB. To select power-down low isolation mode,

apply 5 V to BP-CHA or BP-CHB.

BIASING SEQUENCE

To bias up the ADRF5515A, perform the following steps:

1. Connect any GND pin to ground.

2. Bias up VDD1-CHA, VDD2-CHA, VDD1-CHB, VDD2-CHB, and

SWVDD-CHAB.

3. Bias up SWCTRL-CHAB.

4. Bias up PD-CHAB.

5. Bias up BP-CHA and BP-CHB.

6. Apply an RF input signal.

To bias down, perform these steps in the reverse order.

Table 6. Truth Table: Signal Path

SWCTRL-CHAB

Signal Path Select

Transmit Operation1

Receive Operation

Low

Off

On

High

On

Off

Table 7. Truth Table: Receive Operation, SWCTRL-CHAB = 0 V

Operation

PD-CHAB

BP-CHA, BP-CHB

Signal Path

Receive Operation

ANT-CHA to RXOUT-CHA, ANT-CHB to RXOUT-CHB

High Gain Mode

Low

Low

Low Gain Mode

Low

High

Power-Down High Isolation Mode

High

Low

Power-Down Low Isolation Mode

High

High