Advanced to Analog Converters (DAC) Adam Fleming Mark Hunkele 3/11/2005Slide 2
Outline Purpose Types Performance Characteristics ApplicationsSlide 3
Reference Voltage DAC Digital Value Analog Voltage Purpose To change over computerized qualities to simple voltages Performs opposite operation of the Analog-to-Digital Converter (ADC)Slide 4
DACs Types Binary Weighted Resistor R-2R Ladder Multiplier DAC The reference voltage is consistent and is set by the producer. Non-Multiplier DAC The reference voltage can be changed amid operation. Qualities Comprised of switches, operation amps, and resistors Provides resistance contrarily extent to centrality of bitSlide 5
R f = R V o R 2R 4R 8R MSB LSB - V REF Binary Weighted ResistorSlide 6
Binary Representation R f = R V o R 2R 4R 8R Most Significant Bit Least Significant Bit - V REFSlide 7
Binary Representation SET CLEARED Most Significant Bit Least Significant Bit - V REF ( 1 1 ) 2 = ( 15 ) 10Slide 8
Binary Weighted Resistor R f = R âWeighted Resistorsâ taking into account bit Reduces current by an element of 2 for every bit V o R 2R 4R 8R MSB LSB - V REFSlide 9
Binary Weighted Resistor Result: B i = Value of Bit iSlide 10
Binary Weighted Resistor More Generally: B i = Value of Bit i n = Number of BitsSlide 11
R-2R Ladder V REF MSB LSBSlide 12
R-2R Ladder Same information switch setup as Binary Weighted Resistor DAC All bits go through resistance of 2R V REF MSB LSBSlide 13
R-2R Ladder The less noteworthy the bit, the more resistors the sign muss go through before coming to the operation amp The current is isolated by a component of 2 at every hub LSB MSBSlide 14
R-2R Ladder The current is partitioned by an element of 2 at every hub Analysis for current from (001) 2 indicated underneath R 2R R 2R Op-Amp data âGroundâ B 2 V REF B 1 B 0Slide 15
R-2R Ladder Result: B i = Value of Bit i R fSlide 16
R-2R Ladder If R f = 6R, V OUT is same as Binary Weighted: B i = Value of Bit iSlide 17
2R R 2R Op-Amp information âGroundâ V REF V REF B 2 B 0 R-2R Ladder Example: Input = (101) 2 V REF = 10 V R = 2 Î© R f = 2RSlide 18
Pros & ConsSlide 19
Digital to Analog Converters Performance Specifications Common Applications Presented by: Mark HunkeleSlide 20
Digital to Analog Converters -Performance Specifications Resolution Reference Voltages Settling Time Linearity Speed ErrorsSlide 21
Digital to Analog Converters -Performance Specifications - Resolution: is the measure of fluctuation in yield voltage for each change of the LSB in the computerized information. How nearly would we be able to surmised the wanted yield signal(Higher Res. = better detail=smaller Voltage divisions) A typical DAC has a 8 - 12 bit Resolution N = Number of bitsSlide 22
V out V out Desired Analog sign Desired Analog sign 111 110 1 8 Volt. Levels 2 Volt. Levels 101 100 011 010 001 0 000 Digital Input Digital Input Approximate yield Approximate yield Digital to Analog Converters - Performance Specifications - Resolution Poor Resolution(1 bit) Better Resolution(3 bit)Slide 23
Digital to Analog Converters - Performance Specifications - Reference Voltage Reference Voltage : A predetermined voltage used to decide how each computerized info will be relegated to every voltage division. Sorts: Non-multiplier: inward, altered, and characterized by maker Multiplier: outside, variable, client determinedSlide 24
Voltage 11 10 01 0 00 Digital Input Digital to Analog Converters - Performance Specifications - Reference Voltage Multiplier: ( V ref = Asin(wt) ) Non-Multiplier : (V ref = C) Digital Input Assume 2 bit DACSlide 25
Digital to Analog Converters - Performance Specifications - Settling Time Settling Time: The time needed for the info signal voltage to settle to the normal yield voltage(within +/ - V LSB ). Any adjustment in the data state won\'t be reflected in the yield state promptly. There is a period slack, between the two occasions.Slide 26
Analog Output Voltage +V LSB Expected Voltage - V LSB Time Settling time Digital to Analog Converters - Performance Specifications - Settling TimeSlide 27
Digital to Analog Converters - Performance Specifications - Linearity: is the contrast between the sought simple yield and the genuine yield over the full scope of expected qualities. In a perfect world, a DAC ought to deliver a straight relationship between a computerized data and the simple yield, this is not generally the situation.Slide 28
Linearity(Ideal Case) NON-Linearity(Real World) Desired Output Desired/Approximate Output Approximate yield Analog Output Voltage Analog Output Voltage Digital Input Digital Input Miss-arrangement Perfect Agreement Digital to Analog Converters - Performance Specifications - LinearitySlide 29
Digital to Analog Converters - Performance Specifications - Speed: Rate of change of a solitary computerized info to its simple comparable Conversion Rate Depends on clock pace of information sign Depends on settling time of converterSlide 30
Digital to Analog Converters - Performance Specifications - Errors Non-linearity Differential Integral Gain Offset Non-monotonicitySlide 31
Ideal Output Analog Output Voltage Diff. Non-Linearity = 2V LSB 2V LSB V LSB Digital Input Digital to Analog Converters - Performance Specifications - Errors: Differential Non-Linearity Differential Non-Linearity: Difference in voltage step size from the past DAC yield (Ideally All DLNâs = 1 V LSB )Slide 32
Digital to Analog Converters - Performance Specifications - Errors: Integral Non-Linearity Integral Non-Linearity: Deviation of the genuine DAC yield from the perfect (Ideally all INLâs = 0) Ideal Output Analog Output Voltage Int. Non-Linearity = 1V LSB 1V LSB Digital InputSlide 33
High Gain Desired/Ideal Output Analog Output Voltage Low Gain Digital Input Digital to Analog Converters - Performance Specifications - Errors: Gain Error: Difference in slant of the perfect bend and the real DAC yield High Gain Error: Actual incline more noteworthy than perfect Low Gain Error: Actual slant not as much as perfectSlide 34
Digital to Analog Converters - Performance Specifications - Errors: Offset Error: A consistent voltage distinction between the perfect DAC yield and the real. The voltage pivot capture of the DAC yield bend is not quite the same as the perfect. Yield Voltage Desired/Ideal Output Positive Offset Digital Input Negative OffsetSlide 35
Digital to Analog Converters - Performance Specifications - Errors: Non-Monotonicity Non-Monotonic: An abatement in yield voltage with an increment in the computerized info Desired Output Non Monotonic Analog Output Voltage Digital InputSlide 36
Digital to Analog Converters -Common Applications Generic utilization Circuit Components Digital Audio Function Generators/Oscilloscopes Motor ControllersSlide 37
Digital to Analog Converters - Common Applications - Generic Used when a nonstop simple sign is needed. Signal from DAC can be smoothed by a Low pass channel Piece-wise Continuous Output Analog Continuous Output Digital Input n bit DAC 0 bit 011010010101010100101 101010101011111100101 000010101010111110011 010101010101010101010 111010101011110011000 100101010101010001111 Filter n th bitSlide 38
Digital to Analog Converters - Common Applications - Circuit Components Voltage controlled Amplifier advanced data, External Reference Voltage as control Digitally worked attenuator External Reference Voltage as information, computerized control Programmable Filters Digitally controlled cutoff frequenciesSlide 39
Digital to Analog Converters - Common Applications - Digital Audio CD Players MP3 Players Digital Telephone/Answering Machines 1 2 3 1. http://electronics.howstuffworks.com/cd.htm 2. http://accessories.us.dell.com/sna/sna.aspx?c=us&cs=19&l=en&s=dhs&~topic=odg_dj 3. http://www.toshiba.com/taistsd/pages/prd_dtc_digphones.htmlSlide 40
Digital Oscilloscopes Digital Input Analog Ouput Signal Generators Sine wave era Square wave era Triangle wave era Random commotion era Digital to Analog Converters - Common Applications - Function Generators 1 2 1. http://www.electrorent.com/items/seek/General_Purpose_Oscilloscopes.html 2. http://www.bkprecision.com/power_supplies_supply_generators.htmSlide 41
Digital to Analog Converters - Common Applications - Motor Controllers Cruise Control Valve Control Motor Control 1 2 3 1. http://auto.howstuffworks.com/journey control.htm 2. http://www.emersonprocess.com/fisher/items/fieldvue/dvc/3. http://www.thermionics.com/smc.htmSlide 42
References Cogdell, J.R. Establishments of Electrical Engineering . 2 nd ed. Upper Saddle River, NJ: Prentice Hall, 1996. âSimplified DAC/ADC Lecture Notes,â http://www-personal.engin.umd.umich.edu/~fmeral/ELECTRONICS II/ElectronicII.html âDigital-Analog Conversion,â http://www.allaboutcircuits.com. Barton, Kim, and Neel. âDigital to Analog Converters.â Lecture, March 21, 2001. http://www.me.gatech.edu/charles.ume/me4447Spring01/ClassNotes/dac.ppt. Chacko, Deliou, Holst, âME6465 DAC Lectureâ Lecture, 10/23/2003, http://www.me.gatech.edu/mechatronics_course/Lee, Jeelani, Beckwith, âDigital to Analog Converterâ Lecture, Spring 2004, http://www.me.ga
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