Upload
tam
View
77
Download
1
Tags:
Embed Size (px)
DESCRIPTION
ADC Training. Peter Qian NSSH FAE. Agenda. Review of Definitions Sources of Distortion and Noise Common Design Mistakes ADCs from National Semiconductor. 111 110 101 100 011 010 001 000 1/8 1/4 3/8 1/2 5/8 3/4 7/8 FS - PowerPoint PPT Presentation
Citation preview
ADC Training
Peter QianNSSH FAE
2
Agenda
• Review of Definitions• Sources of Distortion and Noise• Common Design Mistakes• ADCs from National Semiconductor
3
Offset Error
111
110
101
100
011
010
001
000
1/8 1/4 3/8 1/2 5/8 3/4 7/8 FS
ANALOG INPUT (V)
OUTP
UT C
ODE
IDEAL
ACTUAL
OffsetError
NCG 9/99
4
Full-Scale (Offset) Error
111
110
101
100
011
010
001
000
1/8 1/4 3/8 1/2 5/8 3/4 7/8 FS
ANALOG INPUT (V)
OUTP
UT C
ODE
ACTUALFull-Scale
Error
IDEAL
NCG 9/99
5
Gain Error (Full-Scale Gain Error)
111
110
101
100
011
010
001
000
1/8 1/4 3/8 1/2 5/8 3/4 7/8 FS
ANALOG INPUT (V)
OUTP
UT C
ODE SHIFTED ACTUAL
Gain Error
ACTUAL
NCG 9/99
8
Signal-to-Noise and Distortion (SINAD)
SINAD = -20 * Log 10-SNR
10 + 10THD
10
SINAD = 10 * Log10
-SNR
10 + 10THD10
1
1
9
ENOB - Effective Number Of Bits
• ENOB says that the ADC is equivalent to this (ENOB) number of bits as far as SINAD is concerned. That is, a converter with an ENOB of 7.0 has the same SINAD as a theoretically perfect 7-bit converter.
ENOB = SINAD - 1.766.02
1
10
Input Dynamic Range
Dynamic Range is the ratio of the largest to the smallest possible signals that can be resolved. DO NOT confuse with Spurious Free Dynamic Range (SFDR).
Resolution (Bits) Dynamic Range (dB) 6 36.0 8 48.1 10 60.2 12 72.2 14 84.3 16 96.3 18 108.4 20 120.4
Dynamic Range = 20 * Log(2n - 1)
NCG 9/99
11
SFDR - Spurious Free Dynamic Range
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
65dB SFDR
Signal
Highest “Spur”
12
Ideal Case
• THD and SNR curves are linear• SINAD (and ENOB) maximum at –THD = SNR
40.0
45.0
50.0
55.0
60.0
65.0
70.0
75.0
-40 -30 -20 -10 0
SNR (dB)
-THD (dB)
SINAD (dB)
13
Actual Case
• THD and SNR curves nonlinear near 0 dBFS input• SINAD (and ENOB) maximum a little below –THD = SNR
40.0
45.0
50.0
55.0
60.0
65.0
70.0
75.0
-40 -30 -20 -10 0
SNR (dB)
-THD (dB)
SINAD (dB)
Sources of Noise and Distortion
15
Common Sources of Noise and Distortion
• Inadequate Supply Bypassing• Inadequate VA - VDR* Supply Decoupling• Noisy Components/Conditioning Circuitry• Quantization• Clock• Output to Input Coupling
* VDR (or DR VD) is the supply for the output drivers
18
Excessive Clock Jitter (cont’d)
Jitter
NoiseAmplitude
Max Jitter = VIN / (2(n+1) VFS fIN)
19
Jitter Question
Max Jitter = VIN / (2(n+1) VFS fIN)
How much jitter can be allowed in the following- 8 bit ADC- VREF = 2 Volts- ADC Gain = 1- Maximum input of 1VP-P at 40 MHz
Max Jitter = 2V / (2(8+1) 1V 40,000,000)Max Jitter = 2V / (512 40,000,000)Max Jitter = 31.1 ps
3
?
20
Jitter Question (2)
How much jitter can be allowed in the following- 8 bit ADC- VREF = 1 Volts- ADC Gain = 1- Maximum input of 1VP-P at 40 MHz
Max Jitter = 1V / (2(8+1) 1V 40,000,000)Max Jitter = 1V / (512 40,000,000)Max Jitter = 15.5 ps
2
?Max Jitter = VIN / (2(n+1) VFS fIN)
21
Jitter Question (3)
How much jitter can be allowed in the following- 12 bit ADC- VREF = 2 Volts- ADC Gain = 1- Maximum input of 1VP-P at 40 MHz
Max Jitter = 2V / (2(12+1) 1V 40,000,000)Max Jitter = 2V / (8192 40,000,000)Max Jitter = 1.9 ps
3
?Max Jitter = VIN / (2(n+1) VFS fIN)
22
Jitter Question (3)
How much jitter can be allowed in the following-12 bit ADC- VREF = 2 Volts- ADC Gain = 1- Maximum input of 1VP-P at 248 MHz
Max Jitter = 2V / (2(12+1) 1V 248,000,000)Max Jitter = 2V / (8192 248,000,000)Max Jitter = 0.31 ps !
2
?
Allowable Jitter with 0.1VP-P input? 3.1 ps
Max Jitter = VIN / (2(n+1) VFS fIN)
23
Signal Integrity Problem
• Signals propagate down a line• Improper termination causes reflections• Reflections
– Cause signal distortion– Cause signal radiation
• Distortion– Leads to a change in timing– Can lead to timing uncertainty (jitter)– Jitter causes ADC output noise
24
Reflection Problem
• Signals propagate down a line• Improper termination causes reflections
and signal distortion.
25
When is Termination Needed?
• Simple traces need not be terminated• Transmission Lines should be terminated• Trace becomes a transmission line at:
Length >-tr
6 x tPR
Where tr is the digital signal rise timetPR is the signal propagation rate
Typical tPR is about 150ps/inch on board of FR-4 material
4
26
Terminating Analog Lines
• Analog signals are complex waveforms• For single frequencies, traces carrying
analog signals become transmission lines at
Where A is the zero-to-peak signal amplitudef is the signal frequency in MHz
Length >-440
A x x f140A x f=
27
Question: Is Termination Needed?
An ADC clock Signal has a 2ns rise time. The PCB is a typical one of FR-4 material. Beyond what line length should the line be properly terminated??Length >- tr
6 x tPR
2 x 10-9
6 x 150 x 10-12 /in=
103
450Maximum Length = = 2.2 inches (5.6 cm)
2
28
Termination Techniques
• Two Types of Termination– Series – Matches Driver Output to Line
• Rsource + Rseries = ZO
– A.C. – Matches Receiving end to Line • Series RC to Ground
29
Series Termination
• Series Termination: A Series Resistor– Source Impedance + Resistor = ZO
– Resistor placed close to the source• Series Terminate When Source to Resistor
Distance :
Length >-tr
6 x tPR
3
NOTE: See National Semiconductor’s Application Note AN-1113 (http://www.national.com/an/AN/AN-1113.pdf) for controlling line impedance.
tPR is approximately 150 ps/inch or about 59 ps/cm
30
Series Termination Question 1
Develop a Rule of Thumb for the relationship between maximum line length and digital rise time before a trace must be treated as a transmission line
7
L = Max Length >-tr
6 x tPR
L = tR / (6 x tPR )L = tPR / (6 x 150ps/in) = tPR / 900 x 10-12 = tPR / 9 x 10-10
If tPR = 1 ns, then L = 1 x 10-9 / 9 x 10-10 = 10/9 inch per nsL = 1.1 inch per ns of rise time Or, for centimetersL = tPR / (6 x 59ps/cm) = tPR / 354 x 10-12 = tPR / 3.54 x 10-10
If tPR = 1 ns, then L = 10-9 / 3.54 x 10-10 =10/3.54 cm per nsL = 2.8 cm per ns of rise time
?
31
Series Termination QuestionAn ADC sometimes has bad data at the output. It is noted that the clock line is 6 inches long and the clock signal rise time is 2 ns. It is also noted that the ADC data output lines are 3 inches long and have 3.5 ns rise time. The data outputs go directly to an ASIC. What is the first thing you would do to try to solve this problem?
7
? L = Max Length >-tr
6 x tPR
Check to see if clock or data lines are long enoughto be considered transmission lines:L = 1.1 inch per ns of rise timetPR = 2ns, so max line length is 1.1 * 2 = 2.2 inchesAt 6 inches, the clock line should be treated as a transmission line.At 3.5 ns rise time, max length is 1.1 * 3.5 = 3.85 inches,So the 3 inch output data line length is o.k.
32
A.C. Termination
• A.C. Termination: Series RC to Ground at Destination. Needed for “Rat’s Nest”
–R = ZO
–C: C 4 x tPR x LZO
>-
2
Where L is the line lengthZO is the characteristic impedance of the linetPR is the signal propagation rate down a board trace (about 150ps/inch with FR-4 board material)
33
Question (A.C. Termination)
A 7 inch long clock line with a 50-Ohm characteristic impedance needs a.c. termination on an FR-4 board. What is the value of the series resistor and the smallest capacitor that should be used?
2
R = ZO = 50
C 4 x tPR x LZO
>-4 x 150 x 10-12 x 7
50>- 84 pF>-
?
ADC DesignConsiderations
35
Agenda: ADC Design Considerations
• The Analog Input• The Voltage Reference• The ADC Clock• The Digital Outputs
The Analog Input
37
Inadequate Conditioning Circuitry
ADC Input
4.7k
2K
-
+
+5V
-5V
220 220
Input
51
430 pFWhat is wrong with this circuit?
1) Gain of ~2 (could be unstable)2) Possible problem driving sampling input
3
38
Better Conditioning Circuitry
Input220 22pF
ADC Input
47430
2K
-
+
+5V
-5V
22 220
47
62
3.9 nF
What is overall gain of this circuit?
(47/(220+47)) *0.176 * 11.51 =
(220 / (22 * 430)/(22 + 430))2.026
From Input Divider Amplifier Gain Circuit
7
39
Single-Ended Input to Differential Input ADCNOT Preferred Way Best Way
ADC12DL066
IN+
IN-
2V
0V+VCM
+VCM
VCM can be any voltage from 1V to VA / 2. It is acceptable to use VRM.
NOTE: Performance with a single-ended input signal is not as good as with a differential input signal !
ADC12DL066
IN+
IN-
+0.5V
-0.5V
VCM
40
Single-Ended Input to Differential Input Without a Transformer
Best Solution for d.c. and low frequency applications
ADC121S625
IN+
IN-
VCM
LMH6550
41
Single-Ended Customer Issue
What are expected output codes? – peak = 0.0V + peak = 1.0V & output clipped > 1VIs the output as predicted? YES !How should the input circuit look for correct conversion results?
(IN+) – (IN-) = –1V(IN+) – (IN-) = 0 gives code of 800h or 1000 0000 0000 decimal(IN+) – (IN-) = +1V gives code of FFFh or 1111 1111 1111 decimal
Min code: 800hMax code: FFFhWhat is the problem with this circuit?
VREF = 1.0V. What value of (IN+) – (IN-) gives code of 000h?
+1V
–1VDifferential Input
12
Actual output
Desired output
ADC12DL066
IN+
IN-
VREF
2V
0V
1.0 V
42
Recommended Single-Ended Circuit
Here is a better way to bias the input circuit, ensuring that the input common mode voltage is at the mid-scale voltage of the input signal.
NOTE: Performance with a single-ended input signal is not as good as with a differential input signal !
ADC12DL066
IN+
IN-
2VP-P
VCM
VCM
1
43
Recommended Single-Ended Input Circuit for D.C. Applications
NOTE: Performance with a single-ended input signal is NOT as good as with a differential input signal !
1
ADC
2V
0V +1V
IN+
IN-
VREF1.0 V
The Voltage Reference
45
Ramp with Quiet Reference
46
Ramp with Noisy Reference
47
Why Noisy Reference is Worse at High Input Voltages
From ABCs of ADCs :Output = 2n x G x AIN / VREF
So, as the input increases so does the output code and an error in AIN is a larger error when AIN is larger.
1
48
Clean Reference and a Sine Wave
49
Noisy Reference Effect Upon a Sine Wave
50
Clean Reference and a Sine Wave – FFT
Note SNR & Noise Floor
51
Noisy Reference Effect Upon a Sine Wave – FFT
Note SNR & Noise Floor
52
How NOT to Build a Reference
+3V
+3V
+
-
+
-
+
--
+
CM
+3V
+3V
+3V
+3V
REFB
REFT5.49K
1.5K
10K
5K 15K
0.1
0.1
0.1
0.1
10K 11K
1K
1K
316
316
0.1
0.1
0.1 10/10V
2N3906
2N390410/10V
10K
178
178
What is wrong with this circuit?Too Many ComponentsCollector in Feedback PathToo Many AmplifiersToo many different resistor values
5
53
A Better Reference Circuit
+5V
+
-
+5V
+5V
EXTT
82
4.7K
0.1
0.1
10K
0.1
2N3906
2N3904
2K
470
750
2K
750 100
+5V
0.1
10K
100
100-V
LM4040-4.1
10uF, 6V
-
+
10 uF, 6V
1.5K
1.5K
EXTB-V
What is the nominal range of voltages for EXTT and EXTB?EXTT min = 4.1 * 0.75/(0.75+2+0.75) = 0.88VEXTT max = 4.1 * (0.75+2)/(0.75+2+0.75) = 3.22VEXTB min = 4.1 * (0.47)/(4.7+2+0.47) = 0.27VEXTB max = 4.1 * (0.47+2)/(4.7+2+0.47) = 1.41V
13
54
Keep Reference Quiet!
• Use a Tight Layout• “Star” Ground for all Components and
Reference Grounds of ADC• Ground Via Enters Ground at Quiet Point
The ADC Clock
56
Clock Noise
• Clock Can Add Noise• Clock Can Be Noisy, Exhibiting Jitter
– For Ideal SNR, Max Jitter = (VIN/VFS) / (2(n+1) fIN)
• Transmission Line– Clock Line Longer Than tr / (6 * Delay)
Should Be Properly Terminated
2
What effect does sample rate have on max allowable jitter?
None
57
Effect of Jitter
Sampled with “clean” Clock Sampled with Jittery Clock
The Digital Outputs
59
High Capacitance on ADC Outputs
ADC
VDR
RSUB
Driven Device
CIN
Discharge
Charge
CBUS
At what point is at “ground” potential on the die ?
4
So, what does the input see when the output current is dumped into “ground?
Noise
60
Output to Input Coupling
• Output “Talks” to Input– Because of Output Capacitance– Through Substrate
• Limiting Output Current (with Resistors) Can Help
Latch
8 x 47
ADC
VA DR VD
10uFV+
0.1uF
10uF
0.1uF
How is it that these resistors help reduce noise?
By limiting the current that is dumped into the substrate.
2
61
Watch the Time Constant!
• Reduced Amplitude With Increasing Data Rate
• Difficulty Capturing Data– Shortened Capture Window– May Not Cross Logic Threshold
62
Common Design Mistakes
• Inadequate Attention to Noise Minimization– Ignoring PSRR– No Power Decoupling/Bybassing– Noisy Support Components– Excessive Clock Jitter– Treating Clock Line as a Trace– Inadequate Conditioning Circuitry– Inadequate Reference Driver– Inadequate Supply Bypassing– High Capacitance on ADC Outputs
• Overdriving Any Input
ADC LayoutConsiderations
64
The Skin Effect
• Current Seeks The Path of Least Impedance– Entire Conductor at d.c.– Very Thin Skin Above a Few MHz
• Inductance Causes Current to Flow on Skin
• Reduces Conductor Cross Sectional Area• Increases Resistance
65
The Skin Effect: Skin Current
Current flow area
Skin Depth = inches 2.6 * Kf
K = 1r
CU
2
66
Skin Depth vs FrequencySkin Depth vs Frequency for 22 Guage Wire
0.00%20.00%40.00%60.00%80.00%
100.00%120.00%
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Frequency, MHz
Skin
Dep
th, %
Skin Depth vs Frequency for 22 Guage Wire
0.00%
10.00%
20.00%
30.00%
40.00%
0 200 400 600 800 1000 1200
Frequency, MHz
Skin
Dep
th, %
Freq (MHz)
Skin Depth, %
0.0003 100.00%0.001 100.00%0.003 100.00%0.01 100.00%0.03 100.00%0.1 64.74%0.3 37.38%1 20.47%3 11.82%10 6.47%30 3.74%
100 2.05%300 1.18%1000 0.65%
2
67
The Skin Effect: A.C. Resistance
The a.c. resistance of a conductor is much higher than its d.c.resistance.
Rac = 2.61 x 10-7 f x r
2 x (w + h)
where Rac = AC resistance, Ohms/inchf = frequency, Hzr = conductor relative resistivity, compared to copper = 1.00w = flat trace width in inchesh = flat trace height or thickness in inches
68
A.C. Resistance vs Frequency (Typical PCB Trace)
0
0.1
0.2
0.3
0.4
0.5
0.6
0 200 400 600 800 1000 1200
Frequency, MHz
Res
ista
nce,
Ohm
s / I
nch
A.C. Resistance vs Frequency
Freq, MHz Rac0.3 0.00953041 0.01743 0.030137710 0.055023630 0.0953037
100 0.174300 0.30137681000 0.5502363
PCB Trace 0.006" wide by 0.0015" high
69
Question (A.C. Resistance)
What is the a.c. resistance in Ohms per inch at 80 MHz of a typical copper PCB trace that is 0.006 inch wide and 0.0015 inch thick?
Rac = 2.61 x 10-7 f x r
2 x (w + h)2.61 x 10-7 80 x 106 x 1
2 x (0.006 + 0.0015)=
0.002330.015
= = 0.1556 Ohms/inch2.61 x 10-7 80 x 106 0.015
Rac =
?
5
70
Proximity Effect
The Proximity Effect on two conductors carrying opposite high frequency currents causes the a.c. current flow in those nearby conductors to be primarily on the side of the conductors nearest each other.
1
Current flow areas
71
Proximity Effect on a PCB3
IRP = i
H x x (1 +(D/H)2 ) Amps/In
where IRP is the reference plane current density at horizontal distance “D” from the outgoing signal trace i is the signal current H is the height of the signal trace above the reference plane D is the horizontal distance from the edge of the trace.
PC Board
Ground Plane
Signal Trace
Current Densityin Ground Plane
DH
72
Ground Resistance
ADC Resolution (Bits)
ADC LSB Size(uV)
ADC Noise (LSB/Inch)
ADC Noise for 3 Inch Trace Length
(LSB)8 7813 0.07 0.210 1953 0.28 0.812 488 1.13 3.414 122 4.51 13.516 31 17.74 53.2
Ground plane resistance of 0.055 Ohms per inch (at 40 MHz) with an ADC reference voltage of 2.0 Volts can result in significant ground noise that can affect apparent ADC performance with only 10mAP-P of 40 MHz ground current.
73
Skin Effect + Proximity Effect
Current flows in a small area of the trace and reference plane.
1
74
Radiation
• Any Conductor Can– Radiate– Pick Up Signals
• Therefore, Any Conductor Can Be An Antenna
• Greater Loop Area Leads to a Better Antenna
• A Plane Can Radiate• Copper With One Point Grounded can
Radiate
75
Built in Antenna
Antenna
3
76
Previous Suggestion
ANALOGGROUNDPLANE
DIGITALGROUNDPLANE
ADC10321CIVT(TQFP)
32 31 30 29 28 27 26 251
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17 9 10 11 12 13 14 15 16
SwitchingPowerSupply
ADC & Analog Ground Current Flow
HighPowerDigital
Components
Hi-Power Digital Ground Current Flow
1
77
ADC10D040CIVS(TQFP)
48 47 46 45 44 43 42 41 40 39 38 371
2
3
4
5
6
7
8
9
1011
12
3635
3433
3231
3029
2827
2625
13 14 15 16 17 18 19 20 21 22 23 24
SINGLE, UNIFIEDGROUND PLANE
USE POWER TRACES, NOT A PLANE
Another Previous Suggestion
ADC Power Supply path (yellow)
ADC Return current path (brown)
Digital Power Supply path (blue)
Digital Return current path (red)
DigitalComponents
DigitalComponents
PowerSupply
2
78
DIGITAL POWER PLANE
Recommended ADC Layout Example
Use a Single, Solid Ground Plane
NOTE: ADCs DO NOT like Switching Supplies !
Green dots are vias to appropriate PWR or GND plane
ANALOG POWER PLANE
ADC DIGITAL OUTPUT POWER
PLANE
32 31 30 29 28 27 26 25
ADC12020
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
9 10 11 12 13 14 15 16
VREF
VIN+
VIN-
AGND
VA
VA
AGND
PD
D8
D7
D6
VDR
DR GND
D5
D4
D3
VR
M
VR
P
VR
N
VA
AG
ND
D11
D10 D9
DG
ND
CLK
___
OE
DG
ND
VD
D0
D1
D2
11
HIGH PWR DIGITALCOMPONENTSANALOG
CIRCUITRY
DIGITALPWR SUPANALOGPWR SUP
79
Signal Traces vs. Transmission Line
• “Long” Lines Are Not Traces• Transmission Lines Can Distort Signals• Distorted Digital Signals Produce:
– Timing Uncertainty– Clock Jitter
• Through Hole Problem• Layout Can Be Critical
80
Maximum Trace Length
Remember: All traces are transmission lines, but a trace length longer than this absolutely must be treated as a transmission Line:
tR 6 x tPD LMAX =
where LMAX is the maximum line length beyond which that line must be considered a transmission line tR is the signal rise time tPD is the signal propagation rate down the board
81
Summary of Rules
• Use A Single, Unified Ground Plane• Use Separate Power Planes• Keep All Power Planes in
Same Board Layer• Tie Down Grounded Copper Areas
at Many Points• Remember: Traces Are Transmission
Lines
82
Recommended Reading
• High-Speed Digital Design, A Handbook of Black Magic by Howard W. Johnson and Martin Graham, Prentice-Hall, 1993 ISBN 0-13-395724-1
• Analog-Digital Conversion Handbook, the Engineering Staff of Analog Devices,Inc, Prentice-Hall, edited by Daniel H. Sheingold, 1986, ISBN 0-13-032848-0
Evaluating ADCs, WaveVision Explanation
and Demonstration
84
Evaluating ADCs
• Garbage in – Garbage Out– Need spectrally Pure Sine Wave
• Minimize Jitter• Minimize Output Capacitance• Follow Manufacturer Suggestions
– Voltages– Layout
85
WaveVision History• Need for Easy Data Capture & Evaluation• Original WaveVision
– 80 MHz Oscillator on Capture Board– ADC Sample Rates: 80 MHZ Divided by 2, 4, 8, or 16 (40, 20, 10, 5 Msps)
ONLY • WaveVision2
– Added 100 & 120 MHz Osc Possibilities– ADC Sample Rates: 5, 6.25, 7.5, 10, 12.5, 20, 25, 30, 40, 50, 60 Msps– Could use 125 MHz Osc for additional sample rates of 7.8125, 15.625, 31.25,
62.5 Msps, but frequencies incorrectly reported.• WaveVision3
• Added Possibility of Inverting Sample Clock and Delaying Sample Clock by One Master Clock Cycle for Better Timing
• Problem: All Manual Adjustments• WavewVision4
– No Manual Adjustments– Automatically Recognizes Device Board– Virtually Any Sample Rate to 800 Msps Available– Automatically Measures Sample Rate– Better Display Software
WaveVision Demonstration
National’s ADCs
88
High Speed ADCs From National – 8-Bits
* Expected specifications: product in development
Speed(Msps)
Res(Bits)
Pwr. Cons(mW)
INL(LSB)
DNL(LSB)
SNR(dB)
SINAD(dB)
SFDR(dB)
@ fIN
(MHz)ADC
8 15 36 ±0.5 ±0.4 48 46 51 7.5ADC1173
8 20 60 ±0.5 ±0.35 47 46 58 4.4ADC1175
8 50 125 ±0.8 ±0.7 44 44 56 19.9ADC1175-50
8 42 40 ±0.7 ±0.6 45 45 54 4.4ADC08351
8 60 1.3/Msps ±0.5 ±0.4 47 47 60 25ADC08060
8 100 1.3/Msps ±0.5 ±0.4 46.5 46 63 41ADC08100
8 200 1.05/Msps ±0.4 46 46 60 50ADC08200 +1.0 -0.3
8 60 0.65/Msps ±0.5 ±0.25 47.4 46.1 54.5 29ADC08L060
8 1000 1.43 W ±0.35 ±0.25 48 47 58.5 100ADC081000
2 x 8 1000 1.8 W * ±0.5 * ±0.4 * 47 * 46 * 57 * 100ADC08D1000*
89
High Speed ADCs From National – 10-bits
Res(Bits)ADC Speed
(Msps)Pwr. Cons
(mW)INL
(LSB)DNL
(LSB)SNR(dB)
SINAD(dB)
SFDR(dB)
@ fIN
(MHz)10ADC10321 20 98 ±0.45 ±0.35 60 59 72 4.4
2x20ADC10D020 Dual 20 150 ±0.65 ±0.35 59 59 75 4.7
10ADC10030 30 125 ±0.45 ±0.4 59 58 68 13.5
10ADC10040 40 55.6 ±0.3 ±0.3 59.6 59.4 80 19
10 65 68.6 ±0.3 ±0.3 59.3 59 80 32ADC10065
10 80 78.6 ±0.5 ±0.25 59.2 59 78.8 39ADC10080
2x40ADC10D040 Dual 40 267 ±0.65 ±0.35 60 59 72 10.4
90
High Speed ADCs From National 12-bits & Higher
Speed(Msps)
Res(Bits)
Pwr. Cons(mW)
INL(LSB)
DNL(LSB)
SNR(dB)
SINAD(dB)
SFDR(dB)
@ fIN
(MHz)ADC
12 1.5 200 ±0.4 ±0.4 70 69.7 - 0.1ADC12662
ADC12040 12 40 340 ±0.7 ±0.4 69.5 69 84 10
12 62 354 ±1.0 ±0.5 66 65 78 10ADC12L063
12 66 357 ±1.2 ±0.4 65 64 73 25ADC12L0664 x 12 65 840 * ±0.5 * ±0.3 * 66 * 66 * 79 * 32.5ADC12QS065
12 70 640 ±1.5 ±0.65 66 - 74 25CLC5957
ADC12D040 2 x 12 40 600 ±0.7 ±0.4 68 68 80 10
ADC12010 12 10 160 ±0.5 ±0.3 70 69 83 10ADC12020 12 20 185 ±0.55 ±0.4 70 69 85 10
Coming: ADC12DL040, ADC12L065 ADC14L020, ADC14L040
2 x 12 66 686 ±1.2 ±0.5 64 63 72 33ADC12DL066
12 80 357 * ±1.2 * ±0.4 * 65 * 64 * 73 * 25ADC12L080
* Expected specifications: product in development
ADC16061 16 2.5 390 ±3.0 ±1.0 80 79 91 0.514 52 1,400 ±1.5 ±0.3 69 69 80 10CLC5958
91
General Purpose ADCs From National
Coming: ADC082S051, ADC084S06, ADC102S051, ADC124S051
Speed(ksps)
Res(Bits)
Pwr. Cons(mW)
INL(LSB)
DNL(LSB)
SNR(dB)
SINAD(dB)
SFDR(dB)
@ fIN
(KHz)ADC MuxInputs
ADCS7476 12 1,000 10 ±0.4 ±0.5 72.5 72 82 1001
ADCS7477 10 1,000 10 ±0.2 ±0.3 62 61.7 78 1001
ADCS7476 8 1,000 10 ±0.05 ±0.07 49.7 49.7 69 1001
12 500 0.5 ±1 ±1 72.8 72.6 88 100ADC78H89 712 500 0.5 ±1 ±1 72.8 72.6 88 100ADC78H90 8
ADC121S101 12 1,000 10 ±0.4 ±0.5 72.5 72 82 1001
ADC101S101 10 1,000 10 ±0.2 ±0.3 62 61.7 78 1001
ADC081S101 8 1,000 10 ±0.05 ±0.07 49.7 49.7 69 1001
10 500 0.5 ±1 ±1 62 61.7 78 40ADC104S051 4
12 500 0.5 ±1 ±1 73 73 88 40ADC122S051 2
92
Summary - ABCs of ADCs
• The ADC• Review of Definitions• Sources of Distortion and Noise• Common Design Mistakes• ADCs from National Semiconductor
93
National SemiconductorData Converter Web Site
• National Semiconductor’s Data Conversion web site: www.national.com/adc– Application Notes– Data Conversion Calculator– Definitions of Terms (ADC / DAC)– Evaluation Boards, Manuals, Software– Press Releases– Selection Guides– Technical Articles– Technical Presentations– Technical Support Link
94