typical value of Charge pump current?

[savithru]

hi..

I am designing the chargepump circuit. I am using the current mirror configuration.( pls see the attachment for the circuit schematic.)

Now pls tell me what is the typical value of chargepump current.

according to specs LPF should produce .5v to generate the 2.4GHz.

But I am unable to acieve the same. The voltage is always remaining in the range of .93 to ~1v.

pls guide me how to get the proper value ( what is the value?) of my charge pump current.

I wll be very happy if you can give some hints on LPF design also?

pls reply soon.

SavithRu

 

[mooner]

what's the Vth of this process?
Vth of Nmos is 0.6~0.7V in generally, i know. so the spec 0.5V is too small.
in addition, your current maybe changed into low voltage type other than your diode connection.

 

[safwatonline]

use wide swing mirrors

 

[leo_o2]

In my example 5uA .

 

[mooner]

whether 5uA is too small? when VCO produce 2.5G frequency, and three order passive LPF, provided osc input 10M frequency?

 

[kgl_13gr]

What is your supply voltage?
As safwatonline said, your lowest output mirror can't probably be in saturation for low output voltages.