ADF4158 datasheet(34/35 Pages) AD

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ADF4158

Data Sheet

Rev. I | Page 34 of 35

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 48.

LINEAR

FREQUENCY

SWEEP

NO DDS REQUIRED

WITH ADF4158

REFERENCE

OSCILLATOR

26MHz

VCO

ADF4158

PLL

×5

MULTIPLY

×15

×3

ANTENNA

ANTENNAS

76.5GHz

77.0GHz

5.1GHz

5.1333GHz

MICRO-

CONTROLLER

16B

10B

12B

BUS

CAN/FLEXRAY

RANGE

COMPENSATION

BASEBAND

MIXER

DSP

ADSP-BF531

AD9288

AD9203

AD9235

MUX

AMP

ADC

HPF

Figure 48. FMCW Radar with ADF4158

ADF4158 Datasheet(PDF) 34 Page - Analog Devices

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