Data Sheet

ADRF5203

THEORY OF OPERATION

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Rev. 0 | 12 of 15

The ADRF5203 integrates a driver to perform logic functions inter-

nally to provide the advantage of a simplified CMOS-/LVTTL-com-

patible control interfaces. The CTRL pin determines which RF port

is in the insertion loss state and in the isolation state. The EN pin

selects the all off state of the ADRF5203 . When the EN pin is at

logic high, both the RFC to RF1 and RFC to RF2 paths are in the

isolation state. The HIGHZ pin allows the user to choose between

100Ω or high-Z termination for the unselected channel. See Table 6

for the control voltage truth table.

DIFFERENTIAL RF INPUTS AND OUTPUTS

The ADRF5203 is a fully differential 100Ω design. The RF pins

are DC coupled. DC levels of all the RF lines are 0V when there

is no input. When RF1 is selected, RFCN is connected to RF1N,

and RFCP is connected to RF1P. When RF2 is selected, RFCN is

connected to RF2N and RFCP is connected to RF2P.

DC OPERATION

The RF ports are DC-coupled and can support a DC voltage range

of ±8V. Figure 25 shows the DC equivalent circuit for the selected

and unselected channels.

Figure 25. DC Equivalent Circuit

The VCM1 and VCM2 pins can be used to set or monitor the

DC common-mode voltage on the RF ports. The VCMx pins can

be left floating or can be decoupled to ensure a low impedance

common-mode AC ground.

The VCMx pins are internally connected to the RF ports via high

impedance, see Figure 25. When the input signal is driven DC-cou-

pled from the RFC port or the RFx port, the selected RFx port

follows the input signal;therefore, VCM is set by the input signal.

The VCM on the unselected channel can be set via the VCMx

pins. This feature can be used to match the DC level of connected

circuitry. The VCM on the selected channel can also be set at the

VCMx pins if the input signal is AC-coupled.

Power derating must be applied in applications where the common-

mode voltage of selected and unselected channels differ by more

than 8V, see Figure 4.

RF POWER HANDLING

The RF power handling of the ADRF5203 derates over frequencies

below 100 MHz and derating is dependent on the applied DC

voltage . See Figure 3 for power derating towards lower frequencies

for different DC input voltages. For low frequency operation, the

device ensures a constant RON on the selected channel.

For frequencies higher than 100MHz, both the maximum DC volt-

age and maximum RF power can be applied at the same time. See

Figure 2 for power derating frequencies higher than 10GHz.

For use cases where different common-mode DC voltages are

applied at the selected and unselected RF channels, apply the

power derating shown in Figure 4.

The ADRF5203 is designed as bidirectional with equal power han-

dling capabilities on RFC and RFx ports. Either port can be used as

an input or as output.