HMC8411LP2FE datasheet(18/23 Pages) AD

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HMC8411LP2FE

Data Sheet

Rev. A | Page 18 of 23

THEORY OF OPERATION

The HMC8411LP2FE is a GaAs, MMIC, pHEMT, low noise

wideband amplifier.

The HMC8411LP2FE is a cascode amplifier that uses a

fundamental cell of two field effect transistors (FETs) in series,

source to drain. The basic schematic for the cascode cell is shown

in Figure 69, which forms a low noise amplifier operating from

0.01 GHz to 10 GHz with excellent noise figure performance.

RFOUT

RFIN

VDD

Figure 69. GaAs, MMIC, pHEMT, Low Noise Wideband Amplifier Schematic

The HMC8411LP2FE has single-ended input and output ports

with impedances that nominally equal 50 Ω over the 0.01 GHz

to 10 GHz frequency range. As a result, the device can be directly

inserted into a 50 Ω system with external components on the

RF input and output, as shown in Figure 70, without narrow-

banded matching solutions. There is a need for an external bias

choke for VDD on the RFOUT pin followed by a dc blocking

capacitor, as well as a dc blocking capacitor on the RFIN port. On

the RF input, there is an additional resistor, inductor, and

capacitor (RLC) shunt network that aids unconditional stability

below 100 MHz.

The HMC8411LP2FE is a single-supply bias amplifier using an

external resistor on the RBIAS pin to set the IDQ current. To adjust

the IDQ current, change the RBIAS resistor value.

HMC8411LP2FE Datasheet(PDF) 18 Page - Analog Devices