A 1.2GHz adaptive bandwidth type-I PLL using a digital lock detector

This paper introduces a 1.2GHz adaptive bandwidth Type-I PLL with wide bandwidth. PLL operates in wide bandwidth mode during transient to have a fast settling time, and in narrow bandwidth mode during phase lock to more efficiently suppress the sidebands at f
_ref
, 2f
_ref
, etc, at VCO output. The PLL operating mode selection is done utilizing the digital lock detector circuit. The bandwidth of proposed PLL in transient is 5-10 times greater than the bandwidth of traditional Type-I PLL. Operating with a reference frequency of 10MHz, the proposed PLL provides a loop BW of 5MHz in transient, and a spur level of -53dBc. The presented PLL exhibits an in-band phase noise of -118 dBc/Hz at 1MHz offset. PLL total power consumption is 2.5mW.