Capacitor array

hello,
I have this assignment where i have to built a capacitor array using a given voltage supply.
Following things are available to me:
a)Vn = 20V, V1=2V and Vk=V1+(k-1)*(1<k<11, k is an integer)
b)Only one input supply of 2V is available
c)One input clock source of frequency Fclk peak-to-peak 2V is available

I have 10 capacitors , each with a capacitance Cs.
I have to Charge the first capacitor to 2V, second capacitor to 4V and so on, with the last capacitor being charged to 20V.

Switches are also available.

Can anyone provide me with a solution or atleast guide me in the correct direction ..
I do have a solution but it requires the use of a current source which is not available.
Thanx in advance.

This is the 3rd thread on various websites about this same school assignment. Are all the threads from Bladerunner or are they from other kids in his class? ICL7660 charge pump ICs can boost 2V to 4V and to 8V but at a very low current. Something else can boost 8V to the higher voltages but at even lower current. Before we didn't know about 6V.