Pipeline ADC

CSE 598A Project Proposal

James Yockey

Analog to Digital Converters

Review: What does an ADC do?

http://zone.ni.com/devzone/conceptd.nsf/webmain/0A17E22A0530063386256F560071787E

Types of ADC

Flash Pipeline Others…

Flash ADC

http://www.cse.psu.edu/~chip/pdg/prop.pdf

Pipeline ADC

http://www.cse.psu.edu/~ikim/CourseWork/presentation/W8%20ADC.ppt

Pipeline ADC (cont.)

Using two bits for a signal that can vary from 0 to 5V, we can divide it into 4 regions. For example:

00 = 0 to 1.25

01 = 1.26 to 2.5

10 = 2.6 to 3.75

11 = 3.76 to 5.0

Pipeline ADC (cont.)

Assuming each stage produces one bit of output, we need two stages.

Stage one will check if the MSB is 1, i.e. the input is greater than 2.5

If it is, the bit is set to one, and the subtractor subtracts 2.5 from the input.

Stage two will check if the LSB is 1, the incoming voltage is greater than 1.25.

Example: If 3.0V is the input, the MSB is 1, and the voltage sent to stage two is 0.5VStage two checks to see if the voltage is greater than 1.25The output bits are 1 0, which is the correct value.

Pipeline ADC (cont.)

We can design all of the stages to be identical if with the use of an amplifier.

Other types of ADC

Folding Time-interleaved Algorithmic Interpolating Integrating-type

More information can be found at:http://www.cse.psu.edu/~ikim/CourseWork/presentation/W8%20ADC.ppt

Why pipelined?

Less comparators than flashFlash uses 2n, pipelined uses # stages

Smaller Less power Resistor ladder difficult to implement

in CMOS Slower than flash, but still high speed

Application

What can we use this for?

When completed, may be used for: Software defined radio Ultrasound pill Others…

Priorities for design

In order of importance, highest first: Speed Accuracy Error correction Power Area

Specifications

Average Project

Samples/sec (MS/S) 368 200

Bits 10 10

Differential Nonlinearity

Unknown ≤1

Integral Nonlinearity Unknown ≤1

Power (mW) 222 200

Area (mm2) 2.4 1.8

Project Schedule

Week Tasks Comments

Week 1 Circuit research and design

Week 2 Circuit research and design

Week 3 Schematic entry

Week 4 Simulation/Test Spring Break

Week 5 Layout Project Progress Presentation

Week 6 Layout

Week 7 Simulation/Test

Week 8 Simulation/Test

Week 9 Final adjustments Project Final Presentation

Conclusion

Any comments or questions?