13 GHz PLL Synthesizer
The ADF4159 from Analog Devices is a 13 GHz PLL synthesizer that achieves a phase detector operating frequency
of 110 MHz while simultaneously consuming
less than 100 m W of power. The device contains a 25-bit fixed modulus as well as on-chip
functionality to generate highly linear ramp
profiles, making it an ideal solution for fre-quency-modulated continuous-wave (FMCW)
radar applications, including automotive radar
systems. The ADF4159 is also ideal for microwave point-to-point (PtP) systems, communications infrastructure, instrumentation and test
ADI’s ADF4159 fractional-N PLL synthesizer consists of a low-noise digital phase
frequency detector (PFD), precision charge
pump and a programmable reference divider.
It can be used to implement frequency shift
keying (FSK) and phase shift keying (PSK)
modulation. There are also a number of frequency sweep modes available that generate
various waveforms, such as sawtooth and triangular waveforms. The functional block diagram
of the ADF4159 is shown in Figure 1.
ADI’s high-performance ADF4159 PLL
features industry-leading phase noise perfor-
mance of −223 dBc/Hz and 1/f noise perfor-
mance of −
120 dBc/Hz. The very high maxi-
mum PFD frequency allows for very good in-
band phase noise while it also allows for very
wide loop bandwidths if extremely fast settling
time is required.
The ADF4159 is powered by a 2.7 to 3. 3 V
analog power supply and a 1.8 V digital power
supply. The typical current drawn by the part
is 33 mA.
ADI’s ADF4159 PLL can generate a variety
of frequency sweeps or ramps. The ADF4159
is initially programmed once and will contin-