The World Leader in High-Performance Signal Processing Solutions 1.ADCs - Ping-Pong Architectures 2.ADCs – Driving Them 3.DACs – Sinc Compensation 4.DACs – Glitches 5.What They Didn’t Teach You in School Optimizing Data Converters for High Frequency Operation
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The World Leader in High-Performance Signal Processing Solutions 1.ADCs - Ping-Pong Architectures 2.ADCs – Driving Them 3.DACs – Sinc Compensation 4.DACs.
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The World Leader in High-Performance Signal Processing Solutions
1. ADCs - Ping-Pong Architectures2. ADCs – Driving Them3. DACs – Sinc Compensation4. DACs – Glitches5. What They Didn’t Teach You in School
Optimizing Data Converters for High Frequency
Operation
1.2
Ping Pong ADCsReferences
Analog Dialogue 37-8 (August 2003)
Analog Dialogue 39-5 (May 2005)
http://www.v-corp.com/
Do a Patent Search on Inventor: Velazquez; Classification: 341/118
1.3
Nyquist Theorem Limits Frequency Bandwidth
1.4
Ping-Pong ADCSArchitecture
1.5
Ping-Pong ADCSRaw Spectral Response
1.6
Ping-Pong ADCSMatching Requirements
Performance Requirement at 180
MHz
SFDR (dBc)
Gain Matching (%)
Aperture Matching
(fsec)
12 Bits 74 .04 0
12 Bits 74 0 350
12 Bits 74 .02 300
14 Bits 86 .01 0
14 Bits 86 0 88
14 Bits 86 .005 77
1.7
Advanced Filter Bank (AFB)Reduces Spurs Due to ADC Mismatch
1.8
Ping Pong ADCsTrimmed SFDR
1.9
Ping Pong ADCsTemperature Effects
1.10
Linear Error Compensation (LinComp)Corrects for Non-Linearities
1.11
Driving ADCsReferences
Analog Dialogue 39-4 (April 2005)
Analog-Digital Conversion Seminar (2004)
1.12
Transformer Coupling Gives Best High Frequency Performance
1.13
ADC Drive
1.14
Dual Transformers Improve Balance at High Frequencies
1.15
Baluns Have a Wider Frequency Response
1.16
Applying Voltage Gain Can Improve Noise Performance
1.17
DACsSome Things You May Not Have Thought Of
Sinc Compensation Effects
Glitch Energy
1.18
DACs Suffer From Sinc Response
-60
-50
-40
-30
-20
-10
0
0 0.5 1 1.5 2 2.5
Frequency (xFs)
dB
1.19
Use Sinc Compensation to Reduce Passband Droop
Frequency (xFs)
dB
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.20
Passband is Flat But There is 3.5 dB Insertion Loss
Frequency (xFs)
dB
-60
-50
-40
-30
-20
-10
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.21
Sinc Compensation Doesn’t Work So Wellat Super Nyquist Bands
Frequency (xFs)
dB
-60
-50
-40
-30
-20
-10
0
0 0.5 1 1.5 2 2.5
1.22
AD9779 Vs AD9777 Time Domain Plot
AD9777 AD9779
Both DACs synthesizing a 1MHz sine wave in 1x interpolation mode with a 160MSPS clock rate. Due to the unique output stage of the AD9779, its time domain waveform has much more glitch energy than the AD9777
1.23
Glitches Are Worsebut Noise Floor is Better NSD Vs Fout FDATA = 160MSPS 2x Interpolation