Problem 0 - Voltage-variable Capacitor

Design a device like the following picture:

Voltage-variable capacitor.

It should function just like a variable capacitor whose knob is controlled by the input voltage level. This means that even as the voltage changes, the stored charge, Q, should remain the same. The voltage of the capacitor is allowed to clip at the supply voltage, and the entire circuit is allowed to look like a low resistance and release smoke if the capacitor's terminal rises above the rail.

Since the most likely application of this is as a block in tuned circuits of some kind, I'll say that this should be useful in tuning applications up to 1MHz, but I won't define what "useful" means. K should be roughly constant with voltage (maybe within 10%) for the operating range, which is between 0 and the rail.

The implementation technology should be commodity components that could be soldered onto a PCB. If anyone out there wants to do an IC implementation, complete with layout and simulation results extracted from layout, that would be awesome, but I can't give you the hours of your life back, and I hope you realize that you will have created something for free that is only useful to organizations with enough money to fab chips. They could also use this money to pay you. But, if you're devoted enough to your art to realize that and not care, give it a shot.