ADC TYPES. EE174 – SJSU Tan Nguyen. Types of ADC Flash ADC Successive approximation converter Counter Ramp Converter Integrating ADC. Flash ADC Also known as Parallel ADC A n-bit flash ADC uses 2 n-1 comparators and a encoder logic. Advantage: the fastest type of ADC.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
EE174 – SJSU
3-bit flash ADC
Start Conversion (SC)
A DAC is used to generate approximations of the input voltage.
A comparator is used to compare Vin and Vappr.
In each cycle, SAR finds one output bit using comparator.
To start conversion, set SC = 1. When conversion ends, EOC = 1.
Quite fast, expensive, high accuracy and one of the most widely used design for ADCs.
Binary search for a 3-bit ADC
full scale value
D2 D1 D0
1 1 1
1 1 0
1 0 1
1 0 0
0 1 1
0 1 0
0 0 1
0 0 0
clock cycle 2
D1 = 0
[Vin < Vappr]
clock cycle 3
D0 = 1
[Vin > Vappr]
clock cycle 1
D2 = 1
[Vin > Vappr]
3.4 > (5 + 0)/2 = 2.5 Bit 2 = 1
3.4 < (5 + 2.5)/2 = 3.75 Bit 1 = 0
3.4 > (3.75 + 2.5)/2 = 3.125 Bit 0 = 1
1. Understanding Data Converters – SLAA013
2. ADS8318 data sheet – SLAS568A
Evaluating High Speed DAC Performance by Walt Kester – Analog Devices MT-013 Tutorial
Home > Products and Services > White Papers > Understanding Resolution in High-Speed Digitizers/Oscilloscopes