Datasheet

ADF4158 Data Sheet
Rev. E | Page 34 of 36
APPLICATION OF ADF4158 IN FMCW RADAR
The ADF4158 in FMCW radar is used for generating ramps
(sawtooth or triangle) that are necessary for this type of radar to
operate. Traditionally, the PLL was driven directly by a direct digital
synthesizer (DDS) to generate the required type of waveform.
Due to the implemented waveform generating mechanism on the
ADF4158, a DDS is no longer needed, which reduces cost. In
addition, the PLL solution has advantages over another method
(the DAC driving the VCO directly) for generating FMCW ramps,
which suffered from VCO tuning characteristics nonlinearities
requiring compensation. The PLL method gives highly linear
ramps without the need for calibration.
The application of ADF4158 in FMCW radar is shown in
Figure 47.
08728-034
LINEAR
FREQUENCY
SWEEP
NO DDS REQUIRED
WITH ADF4158
REFERENCE
OSCILLATOR
26MHz
VCO
ADF4158
PLL
×5
MULTIPLY
×15
×3
PA
Tx
ANTENNA
Rx
ANTENNAS
76.5GHz
TO
77.0GHz
5.1GHz
TO
5.1333GHz
MICRO-
CONTROLLER
16B 10B
TO
12B
BUS
CAN/FLEXRAY
RANGE
COMPENSATION
BASEBAND
MIXER
DSP
ADSP-BF531
AD9288
AD9203
AD9235
MUX
AMP
ADC
HPF
Figure 47. FMCW Radar with ADF4158