Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic 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

how to implement this circuit?

Status
Not open for further replies.

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
NOW, the output of Circuit A is current signal, how to implement Circuit B so that Circuit C gets what it want current signal from Cuircuit A. Note, we hope that Circuit B is controlable from outside chip.
 

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
It isn't clear what u want to control in B. I can suggest u to look for current amplifier (with gain = 1) or current conveyor citcuits.
 

    samuel

    points: 2
    Helpful Answer Positive Rating

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
ok. thankyou for your reply.

i want to design a Circuit B, which can control freely current from Circiut A to Circuit C。

Can you give me some advice?
 

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
What's "freely"?
What function of circuit B do u expect?
It's a switch (turn-on, turn-off), amplifier with controlable gain. What range of node voltage for link between A and B. U'll need specify this voltage controlable (current conveyor function) or link one with some supply.
Is It PCB circuit or citcuit for on-chip implementation?
 

    samuel

    points: 2
    Helpful Answer Positive Rating

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
ok.
(1)
“freely” just means, for example, if Circuit C needs 300nA current, you can get 300nA current signal from Circuit A through controlling Circuit B; if Circuit C needs 301nA ,you can also do it through controlling Criuit B; and so on. That is to say, controlled continously。(Note: the current signal from Circuit A is larger than the current into Circuit A.)
(2)this circuit is implemented on chip.

(3) the voltage relation between A and C is not important.


thanks again.
 

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
This description looks doubtful. How can i decide what current circuit C is needed? And how can i make control through B, add some fix current value or it's a part of feedback?
It'll better if u show relations by formulas.
 

    samuel

    points: 2
    Helpful Answer Positive Rating

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
Ic=a×Ia (0<a≤1)
(Ia>Ic)
Ia is constant.
Ic is current into Circuit C;
Ia is curretn outof Circuit A;

how to implement this formula?
 

mdcui

Advanced Member level 4
Joined
Aug 23, 2005
Messages
109
Helped
28
Reputation
56
Reaction score
5
Trophy points
1,298
Location
california, USA
Activity points
2,078
looks like a current mirror is what you are looking for, and by control the configuration of current mirror, you can get whatever current you want from B to C, but I am not quite clear about the detailed requirements.
 

    samuel

    points: 2
    Helpful Answer Positive Rating

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
How is "a" related with B?
If u need voltage control I think u need diff. pair circuit like at picture.
(1-a)=Vb/R. Or u can witch diff. pair completely.
 

    samuel

    points: 2
    Helpful Answer Positive Rating

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
ok.

but curent mirror may implement it, but it is discretely controlled, not continously.

that is to say, you can set a=0.1, 0.2, 0.3, and so on. Thus is discrete number, not a real number.

thankyou.

Added after 10 minutes:

Dear DennisMark,

I dont understand your viewpoint.
 

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
Excuse me, I hurried. The previous schematic is incorrect.
But now, your problem becomes more clear.
If current flow direction is appropriate for you, as mentioned before you can use diff.pair to switch/divide current IA and deliver part of one to sink as IC.
If the N mosfets turned on the left and M mosfets turned on the right that IC=(M/N)*IA, a=M/N.
For a=0.1, 0.2, 0.3, and so on u need 10 pair of mosfets (10 mosfets on each side).
Using biasing voltage for turnon switching allows u utilize more simple schematic of current sinker (IC).
 

    samuel

    points: 2
    Helpful Answer Positive Rating

samuel

Full Member level 3
Joined
Nov 15, 2004
Messages
171
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Location
world
Activity points
1,139
now, a is still discrete number, not a real number.
 

DenisMark

Full Member level 6
Joined
Sep 16, 2005
Messages
325
Helped
104
Reputation
208
Reaction score
34
Trophy points
1,308
Location
Russia
Activity points
3,437
It's requred about 10 posts to understand what u want. And up to now it isn't clear how u suggest to control "a".
U should master to pose a problem more clearly from begining.

As i take ur explanation u need this function: Ic = Ia * A.
A changes continuously in dependence of controlling voltage Vb or current Ib. U don't explain what is controlling amount.

So we can reformulate this for linear dependence: Ic = Ia * K * Vb or Ic = Ia * K * Ib, K - factor. I don't know what dependence u need.

As u can see the result function is curent with current or current with voltage multiplication.

I think u work with large signal. So for voltage processing this kind of circuits is named variable gain amplifier (VGA). But i haven't known VGA equvalent for current processing. I need a time to think about.
 

leo_o2

Advanced Member level 4
Joined
Sep 3, 2004
Messages
1,324
Helped
277
Reputation
556
Reaction score
241
Trophy points
1,343
Location
China
Activity points
5,761
What's the transfer function for from Current A to Current C with external controlling? What's the external controlling? It can be adjustable resistor or a voltage? Do you need linear controlling or nonlinear controlling? You need to make clear of your requirement.
 

IBO

Full Member level 3
Joined
Mar 1, 2007
Messages
153
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,298
Activity points
1,980
hi

we just cant think of it as block level

we need schematic info.

whether its MOS implemented or otherwise
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top