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Advanced to Simple Converters (DAC). Adam Fleming Mark Hunkele 3/11/2005. Plot. Reason Sorts Execution Qualities Applications. Reference Voltage. DAC. Advanced Quality. Simple Voltage. Reason. To change over advanced qualities to simple voltages

Transcripts

Advanced to Analog Converters (DAC) Adam Fleming Mark Hunkele 3/11/2005

Outline Purpose Types Performance Characteristics Applications

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)

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 bit

R f = R V o R 2R 4R 8R MSB LSB - V REF Binary Weighted Resistor

Binary Representation R f = R V o R 2R 4R 8R Most Significant Bit Least Significant Bit - V REF

Binary Representation SET CLEARED Most Significant Bit Least Significant Bit - V REF ( 1 1 ) 2 = ( 15 ) 10

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 REF

Binary Weighted Resistor Result: B i = Value of Bit i

Binary Weighted Resistor More Generally: B i = Value of Bit i n = Number of Bits

R-2R Ladder V REF MSB LSB

R-2R Ladder Same information switch setup as Binary Weighted Resistor DAC All bits go through resistance of 2R V REF MSB LSB

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 MSB

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 0

R-2R Ladder Result: B i = Value of Bit i R f

R-2R Ladder If R f = 6R, V OUT is same as Binary Weighted: B i = Value of Bit i

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 = 2R

Pros & Cons

Digital to Analog Converters Performance Specifications Common Applications Presented by: Mark Hunkele

Digital to Analog Converters -Performance Specifications Resolution Reference Voltages Settling Time Linearity Speed Errors

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 bits

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)

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 determined

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 DAC

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.

Analog Output Voltage +V LSB Expected Voltage - V LSB Time Settling time Digital to Analog Converters - Performance Specifications - Settling Time

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.

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 - Linearity

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 converter

Digital to Analog Converters - Performance Specifications - Errors Non-linearity Differential Integral Gain Offset Non-monotonicity

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 )

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 Input

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 perfect

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 Offset

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 Input

Digital to Analog Converters -Common Applications Generic utilization Circuit Components Digital Audio Function Generators/Oscilloscopes Motor Controllers

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 bit

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 frequencies

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.html

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.htm

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.htm

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