A Review on Micro-Watts All-Digital Frequency Synthesizers

Area of Science:

• Electrical Engineering
• Integrated Circuits
• Signal Processing

Background:

• The proliferation of Internet-of-Things (IoT) devices necessitates highly integrated and low-power electronic components.
• Traditional frequency synthesizers often face limitations in power consumption and integration density for IoT applications.
• Complementary Metal-Oxide-Semiconductor (CMOS) technology offers a robust platform for high-density signal processing, making it ideal for advanced synthesizer designs.

Purpose of the Study:

• To review recent advancements in highly integrated all-digital frequency synthesizers.
• To identify and analyze architectures suitable for low-power Internet-of-Things (IoT) applications.
• To establish low power consumption as a primary metric for evaluating CMOS-based all-digital frequency synthesizers.

Main Methods:

• Literature review of recent developments in all-digital frequency synthesizers.
• Focus on architectures implemented in CMOS fabrication technology.
• Categorization of synthesizers into divider-less low-power types: all-digital phase-locked loops (ADPLLs), all-digital frequency-locked loops (ADFLLs), and hybrid PLLs.
• Analysis of architectural innovations for ADPLLs, including Digital-to-Time Converter (DTC)-assisted Time-to-Digital Converter (TDC) and embedded TDC.

Main Results:

• CMOS technology enables high-density, robust signal processing crucial for all-digital phase-locked loops (ADPLLs).
• Divider-less low-power frequency synthesizers, including ADPLLs, ADFLLs, and hybrid PLLs, are key for IoT.
• Architectural improvements like DTC-assisted TDC and embedded TDC contribute to lower power consumption in ADPLLs.

Conclusions:

• Highly integrated all-digital frequency synthesizers in CMOS are essential for low-power IoT applications.
• The review identifies ADPLLs, ADFLLs, and hybrid PLLs as promising architectures.
• Ongoing architectural developments are critical for achieving the stringent low-power requirements of future IoT devices.