Please explain what is the difference between ADF4355 and ADF4355-3?
Recommended for New Designs
The ADF4355 allows implementation of fractional-N or integer-N phase-locked loop (PLL) frequency synthesizers when used with an external loop filter and...
ADF4355 on Analog.com
Comparing the "Features" block on the first page
of the two data sheets reveals the following lines
that are different:
RF output frequency range: 54 MHz to 6800 MHz
Analog and digital power supplies: 3.3 V
Charge pump and VCO power supplies: 5.0 V typical
RF output frequency range: 51.5625 MHz to 6600 MHz
All power supplies: 3.3 V
The "General Description" block on the right-hand side
of the data sheet reveals the following sentences that are
different (and also add new information):
The ADF4355 has an integrated VCO with a fundamental output frequency ranging from 3400 MHz to 6800 MHz.
The ADF4355 operates with analog and digital power supplies ranging from 3.15 V to 3.45 V, with charge pump and VCO supplies from 4.75 V to 5.25 V
The ADF4355-3 has an integrated VCO with a fundamental output frequency ranging from 3300 MHz to 6600 MHz
The ADF4355-3 operates with analog, digital, charge pump, and VCO power supplies ranging from 3.1515 V to 3.4485 V
It's unlikely the ADF4355-3 required a new photomask set.
Modern mixed-signal chips have ways to permanently
modify the behavior of the chip post-fabrication .
What likely happened here was that a customer wanted to
use the ADF4355 in a design that did not have a 5V rail available,
and asked ADI if it was possible to trim a version of the chip that
worked with all rails at 3.3V with reduced specifications. Once
the work was done, there was no reason not to offer the chip
variant to the entire customer base.