8.3.1 Device Block-Level Description

The LMK61E08 is an integrated oscillator that includes a 50-MHz crystal and a fractional PLL with integrated VCO that supports a frequency range of 4.6 GHz to 5.6 GHz. The PLL block consists of a phase frequency detector (PFD), charge pump, integrated passive loop filter, a feedback divider that can support both integer and fractional values and a delta-sigma engine for noise suppression in fractional PLL mode. Completing the device is the combination of an integer output divider and a differential output buffer. The PLL is powered by on-chip low dropout (LDO) linear voltage regulators and the regulated supply network is partitioned such that the sensitive analog supplies are running from separate LDOs than the digital supplies which use their own LDO. The LDOs provide isolation to the PLL from any noise in the external power supply rail. The device supports fine and coarse frequency margining by changing the settings of the integrated oscillator and the output divider, respectively.