This is a small footprint 50 percent duty cycle square wave oscillator with variable frequency from 10kHz to 30MHz. The frequency range can be extended to 1kHz by using 1M instead of 100k for R6.
http://www.triplespark.net/elec/oscillator/LTC1799/
which used the Schmitt inverter circuit which was made with the CMOS.
http://www.hobby-elec.org/e_ckt13.htm
The oscillation frequency can be calculated using a formula
http://www.hobby-elec.org/e_ckt29.htm