Data Sheet

ADRF5515

Rev. 0 | Page 13 of 15

THEORY OF OPERATION

The ADRF5515 requires a positive supply voltage applied to

VDD1-CHA, VDD2-CHA, VDD1-CHB, VDD2-CHB, and

SWVDD-CHAB. Use bypassing capacitors on the supply lines

to filter noise and use 300 Ω series resistors on the BP-CHx and

PD-CHAB digital control pins for glitch and overcurrent

protection.

SIGNAL PATH SELECT

The ADRF5515 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 ADRF5515 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.

Transmit Operation

The ADRF5515 supports insertion loss mode and isolation

mode when in transmit operation, that is, when SWCTRL-

CHAB = 5 V. As detailed in Table 7, with PD-CHAB set to 5 V

and BP-CHA or BP-CHB set to 0 V, insertion loss mode is

selected. Under the same circumstances, isolation mode is

selected by applying 0 V to PD-CHAB.

Receive Operation

The ADRF5515 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 ADRF5515 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 ADRF5515, perform the following steps:

1. Connect GND 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

Signal Path Select

SWCTRL-CHAB

Transmit Operation1

Receive Operation

Low

Off

On

High

On

Off

1

See the signal path descriptions in Table 6.

Table 7. Truth Table: Operation, SWCTRL-CHAB = Low

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