CMOS-Complimentary Mosfet Introduction to CMOS-Complimentary Metal Oxide Semiconductor FET’s Complementary metal oxide semi-conductor devices are chips in which both P-channel and N-channel enhancement MOSFETs are connected in push-pull arrangement. The basic connections for CMOS are shown in figure. The complimentary, high-speed, high voltage, gate-clamped N and P-channel MOSFET pairs utilize an advanced vertical DMOS structure and well-proven silicon-gate manufacturing process.

(this discussion is continued in Oscillators' basics)

In the beginning, there was the original beat. The tightly controlled frequency of a precisely cut quartz crystal that sets the rythm of the rest of the circuit.

Getting this crystal is easy today, getting it to oscillate properly is a totally different thing. Making it work with a discrete complementary MOSFET driver is yet another story.

Half a century ago, our predecessors would use a pair of NPN to run a watch out of a 8192Hz crystal and a small coin battery:

(source: http://ethw.org/First-Hand:The_First_Quartz_Wrist_Watch)

Complementary Mosfets

I haven't seen this topology used since then, people use these circuits instead today:

(see http://www.bowdenshobbycircuits.info/page11.htm)

Complementary Mosfet Switch Circuit

Oh wait, the 2N2904 is a PNP, not NPN type... wth ?

I have already explored discrete Xtal oscillator circuits at https://hackaday.io/project/8121-discrete-yasep/log/26870-clock-generation-circuit but 32KHz is a different and more sensitive domain.

For our purpose, the left circuit (similar to the higher frequency one) is not accepted because it uses an integrated circuit. That would be too easy. On the right, it uses a single bipolar transistor (how 70's !) and the 68K pull-up wastes energy. I want a low-power full CMOS design. Just because.

In theory, the 4069 inverter gate should be easily replaced by a pair of complementary MOSFET. This raises the question of the influence of the combined gate capacitances.

Not shown is the series resistor that K.C. suggested in the comments, I'll have to try it before I commit to the design. For now I'm trying to KISS.

Complementary Mosfet Driver

Also missing is a LC filter between the P-MOSFET and VCC.