Data Sheet

ADL8111

APPLICATIONS INFORMATION

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Rev. A | 21 of 24

The basic connections for operating the ADL8111 are shown in

Figure 86, which is also the schematic for the evaluation board. A

5 V dc bias is supplied to the amplifier on VDD_PA, +3.3 V dc bias

supply to VDD_SW and −3.3 V dc bias supply to VSS_SW.

VA and VB are digital inputs set path states shown in Table 7. High

logic state is set at 1.4 V and low logic state is set at 0 V.

The LNA within the ADL8111 operates in self-biased mode where

the VBIAS pin is connected to a 560 Ω external resistor to achieve

a 70 mA supply current. Refer to Table 9 for the recommended

resistor values to achieve different IDQ currents.

Figure 84 shows the time domain response at RFOUT to switching

voltages on VA and VB when RFIN is driven by a steady level of

approximately 2.5 dBm at 200 MHz. Both of the External Bypass

connections paths (External Bypass A, External Bypass B) are left

open.

With VA and VB low and high respectively, the ADL8111 is in Inter-

nal Amplifier Mode and the observed output level is approximately

4VPP or 16 dBm. With VA high and VB low, device switches to

Internal Bypass Mode, and the output drops correspondingly. With

VA and VB both low or both high, the device switches to either

External Bypass A or External Bypass B. Since these two paths

are left open in this case, no signal appears at the output for both

cases.

Figure 84. Time Domain Response of RFOUT to Switching of VA and VB

Voltages with a Continuous 2.5 dBm RF Input on RFIN

RECOMMENDED BIAS SEQUENCING

During Power-Up

The recommended bias sequence during power-up follows:

1. Set VDD_SW = 3.3 V.

2. Set VSS_SW = −3.3 V.

3. Set VDD_PA = 5 V.

4. Apply the RF signal.

During Power-Down

The recommended bias sequence during power-down follows:

1. Turn off the RF signal.

2. Set VDD_PA = 0 V.

3. Set VSS_SW = 0 V.

4. Set VDD_SW = 0 V.

The bias conditions, VDD_PA = 5 V at IDQ = 70 mA, is the

recommended operating point to achieve optimum performance.

The data used in this data sheet was taken with the recommended

bias condition. Using the HMC8411 with different bias conditions

can provide different performance than what is shown in the Typical

Performance Characteristics section.

Table 9. Recommended Bias Resistor Values at VDD_PA = 5 V

RBIAS (Ω)

IDQ (mA)

226

85

560

70

1.1 k

55