To distribute a current signal instead of a voltage signal

Hi,

it is always said that on chip we should try to distribute a current signal of a voltage signal.

As far as I understand, it is mainly because of the accuracy problem. The voltage signal distribution suffers from the voltage drop or inteference on chip.

But if to distribute a current, then probablely more current and power consumption will be needed.

Would like to know how do you think about this point?

Re: To distribute a current signal instead of a voltage sign

In principal you're alsolutly right. Transfering a voltage accuratly over a chip
is quite difficult. However there are some execeptions. Imagine a voltage reference
for a series of diffamps. Usually the reference voltage is connected to a inputpair
transistor. This however gives us almost no current on the net (if your technology
does not suffer from heavy gate leakage ). Therefore proper shielding or spacing
is good enough here. Having a current on the reference causes a drop, as you have
already mentioned, with all negative side effects
Doing the same with a current mode transfer scheme causes more current
consumption. You need to generate a current wire it all over the chip to the places
you need if and then tranfer it back into a voltage (with local currentmirrors).
This solution is quite nice, but you have to take care about the local gnd level
of the local current mirrors if you're using a n-fet current mirror (vdd for p-fets)
Every solution has it's charm, and I have used both in the past whichout having
problems.

Best Regards

Andi