High speed charge pumps

[Cyrk]

Hi.

I'm looking for some info about CMOS high speed charge pumps (schematics, layout issues ect.). The design i'm curently using is not fast enough.

Thx for any help

 

[nxing]

what do you menas not fast enough? you can increase the current or decrease capacitance to improve the CP gain

 

[alfred]

Small capacitance will fast ur charge pump

 

[Areky_qin]

Small capacitance will fast ur charge pump

Are you make sure? small cap can improve speed?
then how to guarantee the supply current ability?if the output voltage is just used as a reference voltage, you are right, but if the output is used as a supply? then the small cap storage less charge, then the ripple will be large? In order to meet the supply current request, the clk frequency, the currents and the cap have some balance.

 

[Cyrk]

what do you menas not fast enough? you can increase the current or decrease capacitance to improve the CP gain

I dont need higher CP gain, i need faster switching. Right now my CP output is not even close to rectangular inpulses matching PFD output. I need some kind of article or book with detailed explanation of CP various topologies. Or at the very least a 1-20GHz CP schematic. Thx for help in advance, but please spare me posts like "you can increase the current or decrease capacitance". I cannot increase CP output current because i would have to change entire loop dynamic (or at the very least whole filter) and I didn't understood "decrease cap" thing. I'm currently operating with the smallest cap switches in designated technology. It's not the way to go. My CP schematic is simply wrong, so I've asked for some info about CP...

 

[safwatonline]

i don't have any experience in CPs, but here is what i think,u should bias the switch in saturation with good Veff , this will give a low impedence to the Current source "i assumed that u r using switch at drain" this low impedence will take most of the current and should increase the speed, here i assumed that the current is absorbed by the cap. at the drain of the current source.
Correct me if i am wrong?

also i think decreasing the sizes of the switches will decrease the o/p cap. "parasitic" and will decrease the time constant >>better speed