Fundamentals of sampled data systems A/D Converters Architectures - SAR
- Sigma-Delta
- Flash
- Pipelined
D/A Converters Architectures - 1 Bit DAC
- The Kelvin Divider or String DAC
- Thermometer DAC
- Binary-Weighted DAC
- R-2R Ladder DAC
- Segmented DAC
- Oversampling Interpolating DAC
- Multiplying DAC
A/D and D/A Converters State of the Art
Sound Sound Light intensity Temperature Force pH... in other words... ...the Real World
Today’s solution
Successive Approximation Converter Successive Approximation Converter - Why not? It is the most common and easy to use type of converter, with practically all combinations of speed, resolution, channel count, input interface, output interface, size and cost.
- AD7626 is the fastest 16 bit SAR at 10MSPS
- AD7690 is the highest SNR 101.5dB
- AD7468 is the lowest power (570uW at 200kSPS, lower if run slower)
- AD7276 is a good all-rounder, 12 bits, 3MSPS, TSOT-6, 3.6mW
- Unbeatable for high resolution measurements with low-delay
- Unbeatable for multiplexed applications
- Can be optimised for low-power (sleep mode between conversions)
- Can be optimised for low noise (averaging or filtering the output)
Precision Sigma Delta converter Precision Sigma Delta converter - Low noise and accuracy for DC measurements
- Best is AD7190, AD7191, AD7195
- Integrated Sensor conditioning and System-on-chip
- AD779x family have buffers, muxes, current sources, reference inputs to suit various temperature, pressure and other sensors.
- Low power at low data rates
- AD7171 needs only 330uW for full operation (but SAR can be even lower power if put to sleep between conversions at very low sample rates)
- Robustness
- AD7190 has 50/60Hz rejection of 120dB
Fast Sigma Delta converter Fast Sigma Delta converter - Accurate DC and AC measurements, stable over temperature
- e.g. AD7764 has offset & gain drift <1ppm/°C
- Flat frequency response over the pass band
- AD7764 filter has 0.1dB ripple
- Wide Dynamic range over a wide bandwidth
- AD7764 has 115dB Dynamic range
- Robustness
- AD7764 has excellent anti-aliasing performance
Pipelined Converter Pipelined Converter - When you need to retain good AC performance over wide bandwidths or at high signal freqencies
- AD9434 is a 12 bit 500 MSPS converter. ENOB = 10.4 at 450MHZ
- AD9467 is a 16 bit 250 MSPS converter. SFDR = 100dB at 170MHz allowing very small signals to be detected in the presence of very large ones
- When you need to measure a signal with very high sample rate
- AD9286 toggles 2 ADCs to achieve 500MSPS. It is targeted at Oscilloscope applications and other time-domain measurements
Input is purely passive - 1kohm differential input resistor for 85dB SNR (10MHz BW, 2Vpp)
- Driver amplifier may be removed
- Input impedance is real vs. complex
Low NF allows reduced gain before ADC => more linear front-end - Typical Pipeline ADC: NF=22
- -78dBFS at 125MHz, +4dBm fullscale, 0.4W/ADC = -152dBm/Hz
- AD9262: NF=15
- -86dBFS over 10MHz, -3dBm fullscale, 0.35W/ADC = -158dBm/Hz
Technology Leadership: Technology Leadership: Meeting customer need for faster sampling rate No compromise on performance, keeping power to a minimum
Features Features Fast Throughput, High Performance - 10 MSPS (AD7626)
- 6 MSPS (AD7625)
SAR architecture 16-bit resolution with no missing codes SNR: 92 dB Typ, 90dB Min @ 1MHz INL: ±1 LSB Typ, ±2 LSB Max DNL: ±0.3 LSB Typ, ±1 LSB Max Differential input range: ± 4.096V No latency/no pipeline delay Serial LVDS interface Power dissipation 130 mW @ 10 MSPS, 100 mW @ 6 MSPS
The World Lowest Power 16-Bit ADC The World Lowest Power 16-Bit ADC - Lowest Power: 7mW @ 1MSPS
- Power scales linearly with sampling rate like 70W @ 10kSPS
The World Smallest Package in > 0.2MSPS 16-Bit ADC - LFSCP/QFN (SOT23 size) or MSOP
- Pin-Pin compatible with AD768x
The World fastest MSOP/QFN 16-Bit ADC Outstanding DC and AC Performance - 16-Bit No Missing Code
- +/-1.5LSB INL Max
- 20bit effective resolution @ 10kSPS
Ease of use - 2.5V main supply
- 0 to REF input (up to 5V) - lower cost opamp -
- 5V/3.3V/2.5V serial SPI
- Multiple ADC Daisy Chain, Busy Indicator
High Performance High Performance - Maintains leadership position: Smallest, Fastest, Lowest Power
Features - Lowest power:
- 15mW@ 2MSPS w/o reference
- 26mW@ 2MSPS w/reference
- Throughput:
- 2MSPS Turbo= HIGH
- 1.5MSPS Turbo= LOW
- 1.8V/2.5V/2.7V serial SPI
- SNR 97dB w/external VREF
- Pin for pin with AD7985 (16b), AD7944 (14b)
Low Power – 400 μA typical Low Power – 400 μA typical Low Noise – 40 nV rms Programmable Integrated Features for Temperature Sensing - (RTDs, Thermocouples, Thermistors)
- Instrumentation Amplifier (binary gains 1 to 128)
- Excitation Current Sources (10 / 210 / 1000 µA)
- Voltage Reference, Clock
- Input Buffer, Temp Sensor
Superior offset & gain drift specs - Offset = 10 nV/°C; Gain = 1 ppm/°C
Simultaneous 50 & 60 Hz Rejection Supply: 2.7 V to 5.25 V Temp: -40°C to +105°C
KEY APPLICATION BENEFITS 3-wire RTD - 2 matched excitation currents
- 40 nV RMS @ Gain = 64
- Ratiometric Configuration
- 50 & 60 Hz Rejection (-70 dB)
KEY APPLICATION BENEFITS KEY APPLICATION BENEFITS Thermocouple - Internal Reference
- 40 nV RMS @ Gain = 64, 4 Hz Update Rate
- Differential Analog Input
- On-chip VBIAS Centers the Sensor Range
- 50 & 60 Hz Rejection
KEY APPLICATION BENEFITS KEY APPLICATION BENEFITS Flow Sensor - Several channels required
- 40 nV RMS Noise (In-Amp Gain = 64)
- REFIN up to AVDD
- Ratiometric Configuration
- 50 & 60 Hz Rejection (-70 dB)
KEY APPLICATION BENEFITS KEY APPLICATION BENEFITS - 27 nV noise (In-Amp Gain = 128, 4 Hz Update Rate)
- REFIN up to AVDD
- Ratiometric Configuration
- Medium/High Range Weigh Scales (1 count in 112, 000 (±10 mV Input Range))
- 50 & 60Hz Rejection (-70 dB)
Scientific, Test & Commercial Instruments Scientific, Test & Commercial Instruments - Weigh Scales (Retail, Laboratory, Industrial Hopper & Conveyer Scales)
- Chromatography for Chemical Analysis
- Data Acquisition / Analyzers
- Dataloggers
Industrial Automation - PLC/DCS Analog Input Module Front-Ends
- Temperature Controllers
- Pressure Measurement
Medical Instrumentation - Patient Monitoring
- Blood Pressure Measurement, Temperature Measurement, Blood Analysis
KEY BENEFITS KEY BENEFITS High SNR allows accurate digitization - 112dB at 78kHz, 100dB at 2.5 MHz
- Reduced anti aliasing filtering (Sigma/Delta)
Flexibility - Filter Programmability allows application customization
Comprehensive Solution - On Chip Buffer/Amplifiers simplify design - no need for user to select expensive external components
KEY SPECIFICATIONS A/C Performance at 500Msps - SNR = 65.2 dBFS @ Ain up to 250 MHz
- ENOB of 10.5 @ fIN up to 250 MHz
- SFDR = 75 dBc @ fIN up to 250 MHz
LVDS SDR at 500 MSPS (ANSI-644 levels) 1.2 GHz full power analog bandwidth On-chip reference, no external decoupling required Integrated input buffer and S/H Programmable input voltage range: - 1.18 V to 1.6 V, 1.5 V nominal
Low power dissipation - 660 mW @ 500 MSP—LVDS SDR mode
Single 1.8 V supply operation SPI Port for configuration and control - Selectable output data format (offset binary, twos complement, Gray code)
- Power down
- Output Test patterns
- Output timing adjustments
KEY SPECIFICATIONS KEY SPECIFICATIONS A/C Performance at 500Msps - SNR = 47 dBFS @ Ain up to 250 MHz
- ENOB of 7.5 @ fIN up to 250 MHz
- SFDR = 83 dBc @ fIN up to 250 MHz
LVDS SDR at 500 MSPS (ANSI-644 levels) 1.2 GHz full power analog bandwidth On-chip reference, no external decoupling required Integrated input buffer and S/H Programmable input voltage range: - 1.18 V to 1.6 V, 1.5 V nominal
Low power dissipation - 670 mW @ 500 MSP—LVDS SDR mode
Single 1.8 V supply operation SPI Port for configuration and control - Selectable output data format (offset binary, twos complement, Gray code)
- Power down
- Output Test patterns
- Output timing adjustments
1ppm Linearity 1ppm Linearity - 20bit Resolution
- 1ppm DNL & INL
<1ppm Noise - 0.025ppm Low freq Noise
- 9nV√Hz Wide Band Noise
1µs Settling Time <1ppm Drift Low Glitch - 0.4nV·s (5v); 1nV·s (10v)
Output Spans +5V to ±10V
MRI DAC Requirements: MRI DAC Requirements: High Resolution/Accuracy - 18-20 bits minimum for ≥3.0Tesla Systems
Low Noise - Lessens unwanted image artifacts thereby reducing the need for multiple MRI scans
Low Drift - Eliminates system calibrations
Fast Settling Time
Single Channel Configuration for Isolated PLC Systems Single Channel Configuration for Isolated PLC Systems IOUT - 4mA-20mA, 0mA-20mA or 0mA-24mA
- ±0.01% FSR TUE
- 4ppm/oC Output Drift
VOUT - 0-5V, 0-10V, ±5V, ±10V
- 10% over-range
- 0.01% FSR TUE
- 3ppm/oC Output Drift
- Force & Sense capability
Functionality - Internal 5V 10ppm/oC Reference
- Diagnostics/Fault detection
- Output Loop compliant AVDD-2.5V
16-Bit Quad Industrial V/I Output DAC with Thermal Control 16-Bit Quad Industrial V/I Output DAC with Thermal Control IOUT Range: - 4-20mA, 0-20mA or 0-24mA
- 0.06% TUE Accuracy
- 5ppm/oC Output Drift
VOUT Range: - 0-5V, 0-10V, ±5V, ±10V
- 20% Over-range.
- 0.04% TUE
- Vsense + & Vsens -
Functionality - Flexible Digital Interface
- On-chip Diagnostics
- Integrated per channel DC-DC for Dynamic Power Control
- Internal 5ppm/oC Reference
- Housed in 64 – LFCSP (9 x 9mm)
Smart and High- Efficiency Dynamic Power Control (DPC) Smart and High- Efficiency Dynamic Power Control (DPC)
KEY BENEFITS KEY BENEFITS Small: 32 lead TQFP Full 16 Bit Accuracy - 1 LSB DNL
- 1 LSB INL(C-Grade)
- 2/4 LSB INL (B/A-Grade)
Ease of Application - On chip reference buffers
- Bipolar output generated from single 5V Ref
Output control during power on/off - Output clamped to 0V during power on/off
1ppm>1ppm>
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