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

body terminal of NMOS in triple well technology

Status
Not open for further replies.
S

sw0ws1

Junior Member level 1
Joined
Jul 15, 2010
Messages
19
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,283
Activity points
1,428
hi all
my question is about the connection of body terminal of NMOS ( i use triple well technology;in which the body terminal of NMOS can be connected to its source)
the defination of source in circuit is the terminal that has the lowest voltage??? Am i correct??
the case in my circuit is as the following, assuming the drain and source of NMOS are connected to nodes A and B

i have two phases ,A is always connected to 3VDD..........in phase -I, B is connected to 5VDD-Vth
and in phase-II; B is connected to 3VDD-Vth

my question is :the bulk of NMOS should be connected to A or B????????the problem is: in phase-I-->VA < VB
but in phase-II--> VB<VA
so what is the soluation????????????????????
thanks in advance
 

The rule is to connect the body to at most the lower of drain/source voltages, ie at least 3VDD-Vth or below.
There is no rule to state that the body must be tied to either source or drain. It can be any other suitable node.

But your application seems to be a charge pump with your NMOS being the precharge diode. In such cases, you tie the body to 3VDD, and pre-charge node B with the body diode in phase II.
 
  • Like
Reactions: sw0ws1

    S

    sw0ws1

    Points: 2
    Helpful Answer Positive Rating
Thanks for ur reply
yes my circuit is a charge pump and i use the nMOS in last stage to have a voltage fluctuation......but i dont understand this statement "pre-charge node B with the body diode in phase II."
could you please make it clear for me??
thanks in advance
 

cp.png
vout1=node A =3VDD
mO1 and MO2 are the NMOS,VO1 is the node B (it takes the volts 3VDD-Vth and 5VDD-Vth)
my question is about body terminal of MO1
i wish it be more clear now
thanks 4 ur help
 

MO1 is the one that pre-charges the cap through its body diode. If we call the node at the cap as the drain, then it pre-charges the cap via its body-drain diode. So its body should be tied to Vout1.
 
  • Like
Reactions: sw0ws1

    S

    sw0ws1

    Points: 2
    Helpful Answer Positive Rating
Thanksssssssssssss 4 ur reply
what i understand that the body of MO1 will be always connected to node vout1 and this will be valid in the two phases??right
thanks in advance
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top