HMC8108

Data Sheet

Rev. 0 | Page 14 of 18

THEORY OF OPERATION

The HMC8108 is a X-band, low noise converter with integrated

LO buffers that converts RF input signals ranging from 9 GHz

to 10 GHz down to a typical single-ended IF signal of 60 MHz

at its output. See Figure 54 for a functional block diagram of the

circuit architecture of the HMC8108.

The RF input signal passes through two stages of low noise

amplification. The preamplified RF input signal then splits

through an internal hybrid to feed two singly balanced passive

mixers. A power divider followed by three LO buffer amplifiers

drives the two I and Q mixer cores to convert the amplified RF

input frequencies to a 60 MHz typical single-ended IF. A variable

attenuator allows gain control ranging from 10 dB to 30 dB.

RFIN

LOIN

ESD

VCTRL

ATTENUATOR

LNA_VD1

LNA_VG1

LNA1

LNA_VD2

LNA_VG2

IF_Q

IF_I

BUFF_VD

BUFF_VG

LNA2

MIX_VG

HYBRID

MIX

MIX

DIV

BUFF3

BUFF2

BUFF1

Figure 54. Functional Block Diagram of the Circuit Architecture