A universal 0.03-mm2 one-pin crystal oscillator in CMOS

A one-pin crystal oscillator with an integrated load capacitance of 15 pF has been realized in a standard 0.35-μm CMOS technology. Due to the structure of the oscillator and the use of MOS gate capacitance for the load capacitors, the chip area can be very small. The total active area including load capacitors is less than 0.03 mm². The design can be operated with supply voltages in the range of 1.4-3.6 V and allows crystal frequencies in the range of 3-30 MHz. The current consumption of the oscillator core is 180 μA at 10 MHz with 3.3-V power supply. It produces a rail-to-rail output swing, regulated by an amplitude control loop, and has the same flexibility and ease of frequency tuning as a common Pierce oscillator. As no special IC process options are required, the design is very suitable for clock generation in digital very-large-scale-integration chips