A Design of 0.7-V 400-MHz All-Digital Phase-Locked Loop for Implantable Biomedical Devices

A low-voltage controller-based all-digital phase-locked loop (ADPLL) utilized in the medical implant communication service (MICS) frequency band was designed in this study. In the proposed design, controller-based loop topology is used to control the phase and frequency to ensure the reliable handling of the ADPLL output signal. A digitally-controlled oscillator with a delta-sigma modulator was employed to achieve high frequency resolution. The phase error was reduced by a phase selector with a 64-phase signal from the phase interpolator. Fabricated using a 130-nm CMOS process, the ADPLL has an active area of 0.64 mm(2), consumes 840 mu W from a 0.7-V supply voltage, and has a settling time of 80 mu s. The phase noise was measured to be -114 dBc/Hz at an offset frequency of 200 kHz.