Data Sheet

ADRF5142

THEORY OF OPERATION

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Rev. 0 | 8 of 10

The ADRF5142 integrates a driver to perform logic function inter-

nally and to provide the advantage of a simplified control interface.

The driver features a single control input pin, CTRL, that controls

the state of RF paths to determine which RF port is in an insertion

loss state or in an isolation state (see Table 6).

POWER SUPPLY

The ADRF5142 requires a positive supply voltage applied to the

VDD pin and a negative supply voltage applied to the VSS pin.

Bypassing capacitors are recommended on the supply lines to

minimize RF coupling.

The ideal power-up sequence is as follows:

1. Connect the ground.

2. Power up VDD and VSS. Power up VSS after VDD to avoid

current transients on VDD during ramp-up.

3. Power up the digital control inputs. Power the digital control

inputs before the VDD supply can inadvertently forward bias

and damage the internal ESD protection structures. To avoid

this damage, use a series 1 kΩ resistor to limit the current

flowing into the control pin. Use pull-up or pull-down resistors if

the controller output is in a high-impedance state after VDD is

powered up, and the control pins are not driven to a valid logic

state.

4. Apply an RF input signal.

5. The ideal power-down sequence is the reverse order of the

power-up sequence.

RF INPUT AND OUTPUT

All of the RF ports (RFC, RF1, and RF2) are DC-coupled to 0 V,

and no DC blocking is required at the RF ports when the RF line

potential is equal to 0 V.

The RF ports are internally matched to 50 Ω. Therefore, external

matching networks are not required.

The insertion loss path conducts the RF signal between the select-

ed RF throw port and the RF common port. The isolation path

provides high loss between the insertion loss path and the unselect-

ed RF throw port. The unselected RF port of the ADRF5142 is

reflective.

The switch design is bidirectional with equal power handling capa-

bilities. The RF input signal can be applied to the RFC port or the

selected RF throw port.

Table 6. Control Voltage Truth Table

Digital Control Input, VCTRL

RF Paths

RF1 to RFC

RF2 to RFC

Low

Insertion loss (on)

Isolation (off)

High

Isolation (off)

Insertion loss (on)