Looking for CMOS current source for 1.6u technology

[chaitu2k]

current source

i want a cmos current scource for 1.6u technology...it should be able to generate a 50nA current ..no resistors or capacitors...it should be low power...VDD is 2V

 

[guamak_menanak]

Re: current source

Fisrt of all, you are using biggger technology (1.6um)...it's voltage trashold is bigger(about 1V). To use a CMOS current source is very difficult as at least 2 transistor is needed in CMOS tech(NMOS & PMOS)! Unless, you can used only one transistor as for example 1 NMOS and will be functioned as active resistor(as depcited below).

You can use these equation to define your W&L

W/L = 2Id/[Kn(Vgs1 - Vt)*(Vgs1 - Vt1)]
= 2(50n)/[Kn(2 - Vt)*(2 - Vt1)]

* Add your Kn and Vt form your 1.6um parameter.

Try to simulate, I think that circuit sholud works properly!

 

[chaitu2k]

Re: current source

hi
there is no constraint on the number of transistors i need a pretty accurate current value. the nmos threshold is 1v and pmos is -1v

 

[guamak_menanak]

Re: current source

As I mention before, having a cascode design for your current source is very crucial because your Vt is high!

Try to use the equation as I mention in thre previous post by adding the Kn(Conduction Factor for NMOS) and Vt=1! you sholud have your desired current source now!

 

[goodboy_pl]

Re: current source

please specify your requirements; 50 nA is too low to control on chip since it is comparable to leakage currents or even cross talk to other signals on the chip will corrupt its value/accuracy.
in this cases, the system or circuit topology/technique must be changed!

BEST!

 

[chenyk]

Re: current source

It's possible to create 50nA current if the circuit works in subthreshold region.

regards

 

[uladz55]

Re: current source

Hi,

you can check patent 5,949,278 "Reference current generator in CMOS technology"

**broken link removed**

b/rgds

 

[PONDERBOY]

Re: current source

how can i read the patent?

 

[chinito]

Re: current source

you can use MOS peaking current mirror. It is used for low currents but you have to have atleast one resistor.