CMOS time-to-digital converter based on a pulse-mixing scheme

Area of Science:

• Integrated Circuits
• Digital Electronics
• Signal Processing

Background:

• Conventional pulse-shrinking mechanisms in TDCs have resolution limited by element size ratios.
• Environmental factors like temperature and process variations significantly impact TDC performance.
• Existing TDC designs often require larger circuit areas.

Purpose of the Study:

• To propose a new pulse-mixing scheme for TDCs combining pulse-shrinking and pulse-stretching.
• To enhance the temporal resolution and accuracy of TDCs.
• To improve immunity to temperature and ambient variations and reduce circuit area.

Main Methods:

• A double-stage pulse-mixing scheme is implemented, deriving resolution from the time difference between shrinking and stretching.
• An improved cyclic delay line is utilized to eliminate temporal resolution shifts.
• The proposed TDC is fabricated using a TSMC CMOS 0.35-μm DPQM process.

Main Results:

• Achieved an effective resolution of approximately 53 ps with ±13% variation across a 0-100°C temperature range.
• The fabricated chip core occupies a minimal area of 0.02 mm², representing a significant reduction compared to related works.
• Demonstrated low power consumption (90 μW at 1000 samples/s) and reduced sensitivity to thermal and process variations.

Conclusions:

• The proposed pulse-mixing scheme significantly improves TDC performance, offering superior temporal resolution and accuracy.
• The design achieves high performance with a remarkably small circuit area and enhanced stability against environmental changes.
• This work presents a highly competitive TDC solution for applications demanding precision and miniaturization.