A 678-μW Frequency-Modulation-Based ADC With 104-dB Dynamic Range in 44-kHz Bandwidth

Area of Science:

• Electrical Engineering
• Signal Processing
• Integrated Circuit Design

Background:

• Traditional analog-to-digital converters (ADCs) face challenges in achieving high dynamic range (DR) and power efficiency simultaneously, especially in advanced semiconductor processes.
• Delta-sigma converters are common for high-resolution applications but can be power-intensive and complex.
• Frequency modulation (FM) systems offer inherent coding gain through bandwidth expansion, a property not fully exploited in ADC design.

Purpose of the Study:

• To present a novel frequency-modulation-based analog-to-digital converter (FM ADC) architecture.
• To demonstrate high dynamic range and power efficiency by leveraging analog domain bandwidth expansion and digital demodulation.
• To offer a competitive alternative to existing high-DR conversion techniques, particularly delta-sigma converters.

Main Methods:

• The proposed FM ADC architecture utilizes a sinusoidal output voltage-controlled oscillator (VCO).
• A low-resolution successive approximation register (SAR) ADC samples signals in the FM domain.
• Digital signal processing (DSP) is employed for FM demodulation to recover high-resolution analog input samples.

Main Results:

• The implemented FM ADC achieves a dynamic range (DR) of 104 dB.
• It demonstrates a signal-to-noise ratio (SNR) of 99 dB and a signal-to-noise-and-distortion ratio (SNDR) of 71 dB within a 44-kHz bandwidth.
• The converter achieves this performance while dissipating only 678 μW of power, implemented in 0.5-mm² of 65-nm CMOS technology.

Conclusions:

• The FM ADC architecture effectively leverages analog domain processing for performance and digital domain processing for power efficiency.
• This novel approach provides a viable and competitive alternative to delta-sigma converters for high dynamic range applications.
• The design is suitable for implementation in advanced process nodes, offering a new direction in high-performance data conversion.