A 254-nW 20-kHz On-Chip RC Oscillator With 21-ppm/°C Minimum Temperature Stability and 10-ppm Long Term Stability

Area of Science:

• Integrated circuit design
• Analog electronics
• CMOS technology

Background:

• Achieving stable oscillation frequencies across temperature variations is critical for many electronic systems.
• Traditional RC oscillators suffer from significant frequency drift with temperature changes.
• Advanced compensation techniques are needed to meet stringent stability requirements.

Purpose of the Study:

• To design and present a novel temperature compensated RC oscillator (TC-RCO).
• To achieve high temperature stability and low power consumption using standard CMOS technology.
• To investigate and mitigate second-order temperature effects in oscillators.

Main Methods:

• Utilized 130 nm CMOS technology with regular transistors.
• Implemented constant transconductance (gm) biasing for first-order temperature compensation.
• Employed device mismatch-based offset correction and comparator delay compensation for second-order effect cancellation.
• Incorporated a duty-cycling technique for offset correction.

Main Results:

• Achieved a minimum temperature stability of 21 ppm/°C over a -20 to 100 °C range.
• Demonstrated low power consumption: 254 nW in lowest power mode with a 1 V supply.
• Operated in two modes: low power (254 nW avg.) and high stability (345 nW avg.).
• Exhibited long-term stability of 10 ppm after 1 s integration time.

Conclusions:

• The presented TC-RCO effectively compensates for temperature variations, offering superior stability.
• The design balances low power consumption with high performance, suitable for various applications.
• The combination of compensation techniques successfully cancels second-order temperature-dependent effects.