Datasheet

Data Sheet ADF4159
Rev. D | Page 35 of 36
APPLICATION OF THE ADF4159 IN FMCW RADAR
Figure 55 shows the application of the ADF4159 in a frequency
modulated continuous wave (FMCW) radar system. In the FMCW
radar system, the ADF4159 is used to generate the sawtooth or
triangle ramps 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 waveform generating mechanism that is implemented on
the ADF4159, a DDS is no longer needed, which reduces cost.
The PLL solution also has advantages over another method for
generating FMCW ramps: a DAC driving the VCO directly; this
method suffers from nonlinearities of the VCO tuning character-
istics, requiring compensation. The PLL method produces highly
linear ramps without the need for calibration.
ADSP-BF531
AD8283
ADC
10 BITS TO
12 BITS
16 BITS
:
.
.
MULT ×2
ADF4159
VCO
BASEBAND
PA
REFERENCE
OSCILLATOR
HPF
MUX
:
×2
NO DDS REQUIRED
WITH ADF4159
LINEAR
FREQUENCY
SWEEP
MICRO-
CONTROLLER
DSP
BUS
CAN/FLEXRAY
FREQUENCY MODULATED CONTINUOUS WAVE
LONG RANGE RADAR
RANGE
COMPENSATION
MIXER
Tx
ANTENNA
Rx
ANTENNAS
10849-043
Figure 55. FMCW Radar with the ADF4159