HMC8414ACPZN-R7 datasheet(30/34 Pages) AD

30 / 34 page

Data Sheet

HMC8414

APPLICATIONS INFORMATION

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Rev. 0 | 30 of 34

The basic connections for operating the HMC8414 are shown in

Figure 130. AC-couple the RF input with an appropriately sized

capacitor to provide a DC block. The shunt resistor, inductor,

and capacitor (RLC) network on the input of the HMC8414 adds

resistive loss to help stabilize the amplifier by reducing the gain at

low frequencies.

A 3 V to 6 V DC bias is supplied to the amplifier output through a

choke inductor connected to the RFOUT/VDD1 pin (Pin 11). A DC

block capacitor is required after the bias inductor. Some additional

current flows into the VDD2 pin, which must be connected directly

to the supply voltage as shown in Figure 130 (most of the bias

current flows into the RFOUT/VDD1 pin).

The quiescent drain bias current is set by connecting a resistor

between the RBIAS pin and the supply voltage as shown in Figure

130. A 499 Ω resistor is recommended to set the bias current to 90

mA with a 5 V supply.

A logic signal on the VCTRL pin (3 V or 0 V) toggles between

amplifier mode and bypass mode with a Logic 1 selecting amplifier

mode.

Table 10. Truth Table

Parameter

VCTRL

Amplifier Mode

High

Bypass Mode

Low

Use the following recommended bias sequence during power-up to

ensure the amplifier is not damaged:

1. Set VDD1 and VDD2 to 5 V.

2. Set VCTRL to either 3 V or 0 V to toggle between the amplifier

path and bypass path.

3. Apply the RF signal.

The recommended bias sequence during power-down is as follows:

1. Turn off the RF signal.

2. Decrease VDD1, VDD2, and VCTRL to 0 V.

Figure 130. Basic Connections

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