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.

[SOLVED] Gradient problems in current steering DACs

Status
Not open for further replies.

Chinmaye

Full Member level 3
Joined
Jan 18, 2016
Messages
164
Helped
0
Reputation
0
Reaction score
1
Trophy points
1,298
Activity points
3,145
Hello all,
I have been hearing about gradient errors in current steering DACs. Could someone help me understand what it is?
Thank you
 

Have you ever cut bread? Have the slices always been the same, ideally equal with uniform thickness? Have the air bubbles in the bread been always identical, with the same shape and volume?
 
Non-linearity errors (DAC or ADC) are usually caused by IC production tolerances and/or bad IC design (power distribution)
 

Across-wafer uniformity of transistor attributes is never
ideal and often contains a gradient in addition to random
mismatch. The gradient is not necessarily linear nor
monotonic (e.g. wafer bowing may cause depth-of-field
related photo errors that make center lower than both
edges for some param, or whatever).

If you have a wafer-scale gradient then you have a
chip-scale gradient (of lesser magnitude).

There can also be thermal gradients especially on parts
that have an output buffer / driver that dissipates much
power. In such cases special care with matched devices'
location, orientation relative to the on-chip thermal
gradient is required to avoid "bad IC design". Far from,
and matched-rack orthogonal-to, is about all you can
do. However even this may be a compromise, such as a
case where the output buffer high and low sides can't
be merged neatly, and the thermal gradient in the low,
max load case will be different vector than the high,
max load output case. Then you have to do your best
and eat the rest.

Distributing MSB, MSB-1, ... higher order bits as segments
can help major carry DNL and gradient issues.
 
Have you ever cut bread? Have the slices always been the same, ideally equal with uniform thickness? Have the air bubbles in the bread been always identical, with the same shape and volume?

No. I understand now. Thank you
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top