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.