Design of a Bandgap Reference Circuit for MEMS Integrated Accelerometers

Area of Science:

• Electrical Engineering
• Microelectronics
• Analog Circuit Design

Background:

• Integrated accelerometers require stable, high-precision reference voltages.
• Existing designs often struggle to balance wide supply voltage ranges, high current drive, and low power consumption.
• CMOS/BiCMOS technology presents opportunities for advanced circuit solutions.

Purpose of the Study:

• To propose and validate a novel bandgap reference operational amplifier (op-amp) circuit.
• To meet stringent requirements for integrated accelerometers, including wide supply voltage, high current drive, and low power.
• To demonstrate engineering practicality and broad applicability in sensor systems.

Main Methods:

• Implementation of a CMOS/BiCMOS op-amp circuit.
• Utilizing a folded-cascode input stage and a Class-AB output stage.
• Incorporating adaptive output switching, composite frequency compensation, overcurrent protection, and noise suppression techniques.

Main Results:

• Achieved output swing of 0.2 V~2.8 V with a low-frequency gain of 102~118 dB.
• Demonstrated a Power Supply Rejection Ratio (PSRR) of 90 dB at 60 Hz and overcurrent protection of ±25 mA.
• Maintained static current below 150 μA across the supply range, with line/load regulation better than 150 μV/V and 150 μV/mA, respectively.

Conclusions:

• The proposed op-amp design successfully balances high drive capability and stability under strict power constraints.
• The circuit is well-suited as a bandgap reference buffer stage for integrated accelerometers.
• The design exhibits strong engineering practicality and potential for widespread application in microelectronic systems.