A Direct Feedback FVF LDO for High Precision FMCW Radar Sensors in 65-nm CMOS Technology

Area of Science:

• Electrical Engineering
• Integrated Circuit Design
• Radar Systems

Background:

• High-precision frequency-modulated continuous-wave (FMCW) radar systems require stable power supplies to maintain sensor resolution.
• Power supply ripple can significantly degrade the performance and accuracy of sensitive electronic components like FMCW radar sensors.

Purpose of the Study:

• To present a novel direct feedback flipped voltage follower (FVF) low-dropout (LDO) regulator specifically designed for high-precision FMCW radar applications.
• To enhance the power supply rejection ratio (PSRR) and minimize the impact of power supply noise on FMCW radar performance.

Main Methods:

• Implemented a direct feedback FVF LDO architecture incorporating a folded cascode error amplifier (EA) in the outer loop to boost open-loop gain.
• Utilized a super source follower with the FVF to create a fast feedback loop, ensuring stability and improved transient response.
• Analyzed stability and parameter variation sensitivity using state matrix decomposition for the multi-loop FVF LDO.

Main Results:

• The fabricated FVF LDO, implemented in TSMC 65 nm CMOS technology, successfully supplied a maximum load current of 20 mA from a 1.2 V power supply.
• Achieved a full-spectrum power supply rejection (PSR) with a low-frequency power supply rejection ratio (PSRR) of 66 dB.
• Demonstrated a unity-gain bandwidth of 469 MHz and a rapid 20 ns transient settling time for a load current step from 1 mA to 20 mA.

Conclusions:

• The proposed direct feedback FVF LDO effectively suppresses power supply ripple, crucial for enhancing the resolution and accuracy of FMCW radar sensors.
• The design offers a robust solution with excellent PSRR and transient response, suitable for demanding high-precision radar applications.