All-digital pulse-expansion-based CMOS digital-to-time converter

Area of Science:

• Electrical Engineering
• Integrated Circuit Design
• Signal Processing

Background:

• Digital-to-time converters (DTCs) are crucial components in various electronic systems.
• Existing DTC designs often rely on complex principles like Vernier or require costly digital-to-analog converters.
• Improving timing resolution and reducing power consumption in DTCs remain key challenges.

Purpose of the Study:

• To present a new all-digital CMOS digital-to-time converter (DTC) based on pulse expansion.
• To demonstrate improved timing resolution and a concise design without complex circuitry.
• To achieve high performance with low power consumption and cost.

Main Methods:

• Developed an all-digital pulse-mixing scheme for pulse expansion to enhance timing resolution.
• Designed a DTC comprising a pulse generator, a pulse-expanding circuit (PEC) with a delay chain and multiplexer, and a time subtractor.
• Implemented a pulse neutralization technique to mitigate pulse variation and improve accuracy.

Main Results:

• Fabricated a 4-bit DTC in a 0.35-μm CMOS process with a compact area of 0.045 mm².
• Achieved an improved timing resolution of approximately 16 ps and low integral nonlinearity (< ±0.4 LSB).
• Demonstrated low power consumption (0.2 mW at 1M samples/s, 3.3 V supply).

Conclusions:

• The proposed pulse expansion technique offers a cost-effective and power-efficient solution for digital-to-time conversion.
• The DTC achieves acceptable resolution without necessitating an advanced CMOS process.
• This work represents the first application of pulse expansion in digital-to-time converter design.