current mode and voltage mode ckt

[mohdiliyasmalik]

Can u tell what is the diffrence between current mode and voltage mode circuits?. And where I get some materials about the current mode circuit.For what purpose we do current mode designing?

 

[DZC]

Generally spesking,Current Mode circuit are useful in high speed circuit design,say CML(current mode logic).
However,at the expense of power consumption...
I recommend you some book in this subject as follows:
1.Model and Design of Bipolar and MOS Current-Mode Logic
2.CMOS Current-Mode Circuits for Data Communications
3.Low-frequency analog integrated circuit design using current-mode techniques(Phd dissertation)

You can check this forum for all of them/

 

[mists]

may you give the link of
"3. Low-frequency analog integrated circuit design using current-mode techniques(Phd dissertation) " thanks!

 

[akhilrathore]

I hopr u'll find this helpful.

 

[rvionics]

If you are talking about Switch mode technology, current mode converters have two loops one inside other, one for current & the other for voltage & there are advanteges in some of the topologies over voltage mode. but current mode f/b loops are difficult to stabilize. voltage mode f/b loops are easy to stabilize in comparision. current mode gives larger degree of over load protection in terms of speed & saturation of magnetic element.

 

[vaibhavar]

Hi DZC,
can u please attach the first 2 books you mentioned or some pointer to where i can find them...



thanks in advance
Vaibhav

 

[LvW]

Can u tell what is the diffrence between current mode and voltage mode circuits?. And where I get some materials about the current mode circuit.For what purpose we do current mode designing?

Hi Mohdiliyasmalik,

here is another interesting document which compares both modes (see attachement)

 

[eem2am]

hello,

interesting also to look at it from an EMC point of view.

current mode typically gives better regulation but poorer EMC performance.

Voltage mode typically gives less agressive changes in pulse width (generally speeking) and so is nicer for EMC.

there is another mode also...it is called ON/OFF mode...or like hystereitc mode...also there is clocked hysteretic mode...this is like in LNK304 from power integrations....ut only gets used at low power cuzz its very bad from an EMC point of view...but otherwise gives excellent regulation and transient response.

ON/OFF control needs no compensation component consideration whatsoever.

however, in spite of its excellent regulation and simplicity..it is only used at low powers due to the EMC problem...

its little stated but the main reason behind current mode and voltage mode schemes is the EMC perspective.

PWM feedback compensation is mainly about EMC as its actually easy to get good regulation and transient response (just look at the LNK304 and family)