Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Looking for CMOS current source for 1.6u technology

Status
Not open for further replies.
C

chaitu2k

Member level 3
Joined
Apr 27, 2004
Messages
55
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
501
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
 

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!
 

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
 

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! :D
 

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!
 

Re: current source

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

regards
 

Re: current source

Hi,

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

**broken link removed**

b/rgds
 

Re: current source

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

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top