SAR ADC Styling fulfillment - Assignment Example

ABSTRACT The SAR-ADCs refer to the successive-approximation-register (SAR) analog-to-digital converters have become a common application in the market. They usually provide for up to 5Msps sampling rates with resolutions. These resolutions range from 8 to 18 bits. The SAR architecture caters for high performance, low-power ADCs to be packaged in small form factors for the day to day increasing demand for better applications. The design in this case implements the capacitor array to achieve relatively high speeds and average resolution. The SAR architecture caters for high performance, low-power ADCs to be packaged in small form factors for the day to day increasing demand for better applications. The design in this case implements the capacitor array to achieve relatively high speeds and average resolution. The use of capacitor matching is relatively better than the use of resistors. The SAR- ADC is quite useful for lower sampling rate and higher resolution. The main application for sigma-delta is found in the voice band, in some industrial measurements and audio applications. The model is quite useful for data acquisition. It has resolution that ranges from 8 to 18 bits. It also has a sampling rate that ranges from 50 kHz to 50MHz. This analog to digital converter is capable of achieving very high speeds and it is quite reliable. It provides standard accuracy compared to other types of data converters. There is a reasonable tradeoff between speed and cost and it is able to output the binary number in serial form. The unfortunate bit is that this ADC does not achieve higher resolutions and when it does it is much slower. TABLE OF CONTENTS ABSTRACT 1 TABLE OF CONTENTS 2 INTRODUCTION 2 SAR ADC ARCHITECTURE 4 APPLICATION OF ADC 5 CAPACITIVE EFFECT 5 RESISTIVE EFFECT 5 74LSOO 5 APPARATUS 6 PROCEDURE 6 RESULTS 7 DESIGN 8 IMPLEMENTATION 8 DISCUSSION 9 CONCLUSION 9 REFERENCES 10 Hasanbegovic, A., 2010. Successive approdximation Register (SAR) analog to digital converter (ADC). [Online] Available at: http://www.uio.no/studier/emner/matnat/ifi/INF4420/v10/INF4420%20Project.pdf 10 INTRODUCTION One of the fundamental building blocks in integrated circuit design are the data converters. They interface the analog and digital domains. They can be realized in a number of ways such as SAR ADC. The SAR-ADCs refer to the successive-approximation-register (SAR) analog-to-digital converters have become a common application in the market. They usually provide for up to 5Msps sampling rates with resolutions. These resolutions range from 8 to 18 bits. The SAR architecture caters for high performance, low-power ADCs to be packaged in small form factors for the day to day increasing demand for better applications. The design in this case implements the capacitor array to achieve relatively high speeds and average resolution. The use of capacitor matching is relatively better than the use of resistors. Electronic systems are either analog or digital. Electronic systems use electricity to transmit information[Ali10]. They gather, store, process, transport, and present information. They distribute and convert energy between various forms. Analogue components transmit information using continuous signals while the digital components use discrete signals. The information is encoded in magnitude of voltage and/ or current for the analogue equipment while it is encoded in combination of voltages in discrete form for digital equipment. An analog signal is very fast in processing information and it tends to degrade gracefully. It is infinitely precise in principle. On the other hand, the digital signals are less prone to disturbances as opposed to analog signals. It is good at removing transmission noise. It always allows complex functions to be applied for both software and hardware. The real world operates in analog form and the inputs to a system are usually in analog form. Inputs are obtained from the environment through the sensors, actuators, and signal conditioning. The signals are in continuous form at input, they are processed and stored in digital form. Digital form has more applications and innovations as compared to the analog signals. The digital signals are converted back to analog signals for use in the external environment. Digital circuits use transistors. The digital signals are represented in bits or binary digits as 0 or 1. In practices it is defined by voltage or current being above or below a threshold. The digital data is very fragile especially during transmission [WAl09]. The digital data can be easily corrupted as the noises can change a 1 to 0 or 0 to 1. In the recent developed technological age, components are packaged as Integrated Circuits. These are packed to contain both analog and digital devices. The combination of the two introduces unanticipated noises or errors which could affect the output of an IC. In the performance metrics and co-design, hardware, digital, IC, software, analogue, and PCB are measured against their performance, power consumption, and cost. Electronic systems contain analogue and digital components as well as passive and active components. They are hosted in multilayer PCBs. Components are connected using wires in PCBs. Wires are placed close to each other and their interaction could affect the performance. The electronic systems contain both analogue and digital components within a single PCB or package. Their interaction to each other could lead to unexpected and undesired behavior. The successive-approximation converter has more complex circuitry as compared to the digital-ramp ADC; it has a way shorter conversion time. These converters have a fixed value of conversion time that hardly depends on the rate of the analog input. SAR ADC ARCHITECTURE The SAR- ADC is quite useful for lower sampling rate and higher resolution. The main application for sigma-delta is found in the voice band, in some industrial measurements and audio applications. The model is quite useful for data acquisition. It has resolution that ranges from 8 to 18 bits. It also has a sampling rate that ranges from 50 kHz to 50MHz. The most effective way to create Giga-rate application with up to 16 bit resolution. The architecture is composed of fewer blocks such as comparator, control logic and a converter. There are several merits and drawbacks associated with the SAR-ADC architecture and application. (i) It has a good speed to power ratio. (ii) It has a compact design when compared to flash ADC; this contributes to the cost effectiveness of an SAR-ADC. (iii) It is, however, limited in that it has one comparator in the architecture which works throughout the entire conversation process. Any offset errors in the comparator reflect on the all conversion bits. (iv) The static parameter errors hardly affect the dynamic behavior of the SAR-ADC There is an engineering practice that ensures that all signals that are transmitted are received correctly as intended. This practice ensures that signals do not interfere with one another in a way to degrade reception[Wei11]. They ensure signal do not damage any device and that they do not pollute the electromagnetic spectrum. Losses degrade the signal amplitude, the signal edge rate, and ultimately it becomes a basic speed limiter of our current technology. This causes severe problems for long buses and significant timing push-outs. APPLICATION OF ADC Analog to digital converters are used virtually everywhere as long as analog signal required to be processed, stored, or transported in digital form. The ADC usage are digital volt meters, cell phones, thermocouples, and digital oscilloscope. There are two processes in the ADC process namely: (i) Sampling and holding (ii) Quantizing and encoding There is a huge benefit in holding signals as it ensures the accuracy of the analog to digital conversion. The minimum sampling rate is usually at least twice the highest data frequency of the analog signal. The smallest change in an analog signal that is enough to result in a change in the digital output is the resolution. It represents the quantization error that is inherent in the conversion of the signal to digital form (Zargar, 2010). Partitioning the reference signal range into a number of discrete quanta, then matching the input signal to the correct quantum is quantizing while encoding has to do with assigning a unique digital code to each quantum, then allocating the digital code to the input signal. CAPACITIVE EFFECT The accuracy of analog to digital conversion has an impact on overall system quality and efficiency. There is need for every system for one to improve accuracy needed to understand the errors associated with the ADC and the parameters affecting them. There are different techniques available for converting analog signals to digital outputs. The technique employs the binary search method. RESISTIVE EFFECT 74LSOO The digital components can be manipulated to give different functions. A 2-input NAND gate falls in the 74xx series or family. Looping back a 74LSoo forms a NOT gate. The not gate inverts a single input. Two inputs are passed through a NOT gate, then it is later passed again through another NOT gate. The inverted inputs end up reflecting the initial input after being inverted twice. The result however is a combination of the two inputs. APPARATUS (i) Oscilloscope (ii) Inductor (iii) Resistor (iv) Connecting wires PROCEDURE (i) Investigate the error against resistance and pulse width (ii) Investigate ringing against resistance and capacitance (iii) Form an inductor by coiling a solenoid on an insulator (iv) Insert inductance in series with output and no explicit capacitance (v) Look for ringing on rising and falling edges (vi) Measure oscillation dimensions (time and amplitude) and determine the source of capacitance (vii) Compare and change the inductance. The ringing produced by the system now is compared with the previous type of ringing. RESULTS (a) Capacitive effect The output measured by the oscilloscope across the capacitor using probes, The capacitance is measured as 1µF (b) RC effect The resistance and capacitor effect on the electronic system. The successive approximation ADC circuit uses an n-bit DAC to compare DAC and original analog results. It uses the successive approximation registers inputs to supply an approximate digital code to DAC of Vin. This analog to digital converter is capable of high speed and it is reliable. It provides medium accuracy compared to other types of data converters. There is a good tradeoff between speed and cost and it is capable of outputting the binary number in serial form. The unfortunate bit is that this ADC does not achieve higher resolutions and when it does it is much slower. DESIGN The project seeks to design a 12-bit SAR ADC that has components such as the control logic circuit, a shift register another DAC, a voltage comparator, and a timing generator. When the analog input is filtered it goes through the sample and hold circuit. This sample and hold circuit is contained in the sample hold device module. The quantitative approximation obtained is quantized and encoded. The SAR process has ensures several comparisons are made between the analog input signal and the reference voltage. There are eight modules in the analog to digital converter in the entire layout design. There is the clock circuit, the ADC module, the DAC module, the sample holder module, reference voltage selector, an input filtering device, the latch module, and the comparison circuitry. The clock circuit provides 1 MHz clock signal. There is an operating sampling frequency of 76.923 KHz that acts as the initiating signal for the entire circuit[Ami10][Vic09]. There are control signals for the shift register. The ADC module generates shift signals to control the D- flip flops and their working sequence and it holds updates of the converted digital output temporarily. The signals of the real world analog input module is majorly a sine wave input, a DC input, or a hybrid waveform of sine wave input. Ambient noises generated from internal components and those that impact the system from outside are filtered using the filtering module devices. The speed of the entire data converter depends on the conversion speed and accuracy of the DAC module. The R-2R ladder resistor DAC is a common implementation of the SAR-ADC converter. IMPLEMENTATION Multisim is a common software used to run tests on modules in the electronic system design. The software is able to perform various manipulations on the electronics. The implementation is done by setting the DAC reference voltage to 5 volts. It is supplied with an input DC voltage of 1V. According to the simulation, data inputs were converted after a few microseconds. The value of the data converted can be referenced to the amount of voltage it represents. A power analysis was used to calculate the implementation power. The power is measured to check if implementing all the module consumes excessively more than it should. The method consumes lesser than other methods or types of analog to digital converters. The SAR ADCs has competitive merits and it is more suitable than the other types. Speed of processing is key factor when checking the performance of an electronic system. The looping of digital components saves up by having component reuse and reduces chances of having more disturbances in the system. DISCUSSION At DC or very low frequencies, the current flowing in a conductor will spread out as much. The DC losses are dominated by the cross sectional area and the resistivity of the signal conductor. The current in a typical ground plane will spread out so much that the DC plane resistance is negligible. The DC losses of FR4 are very negligible. At higher frequencies, current concentrated at the surface of the conductor is the skin effect. The Resistor-capacitor model works for CMOS works well on an on-chip wire. The LC model is acceptable for PC board traces. The cross talk effect is the coupling of energy from one line to another through mutual capacitance and mutual inductance for electric and magnetic field. The mutual inductance will induce current on the victim line opposite of the driving current following the Lenz law. The mutual capacitance passes the current through the mutual capacitance that flows in both directions on the victim line. CONCLUSION In a nutshell, the analog to digital converter is a very important module in most electronic gadgets. This module enables the analog inputs to be collected from the environment and processed then output to the external environment in analogue form. The processing part is done in digital form. The SAR ADC architecture is efficient and easy to understand and suited for a modern fine line CMOS process. The lack of latency makes it ideal for single shot and multiplexed data acquisition applications. The CMOS processes allows the addition of a variety of digital functions such as automatic channel sequencing and auto-calibration. They have on-chip temperature sensors and voltage reference. It is the most suitable choice for modern implementation of data converters and data acquisition systems. REFERENCES Ali10: , (Zargar, 2010), WAl09: , (Kester, 2009), Wei11: , (Wu, 2011), Ami10: , (Hasanbegovic, 2010), Vic09: , (Prasertcharoensuk, 2009), Read More

The real world operates in analog form and the inputs to a system are usually in analog form. Inputs are obtained from the environment through the sensors, actuators, and signal conditioning. The signals are in continuous form at input, they are processed and stored in digital form. Digital form has more applications and innovations as compared to the analog signals. The digital signals are converted back to analog signals for use in the external environment. Digital circuits use transistors. The digital signals are represented in bits or binary digits as 0 or 1.

In practices it is defined by voltage or current being above or below a threshold. The digital data is very fragile especially during transmission [WAl09]. The digital data can be easily corrupted as the noises can change a 1 to 0 or 0 to 1. In the recent developed technological age, components are packaged as Integrated Circuits. These are packed to contain both analog and digital devices. The combination of the two introduces unanticipated noises or errors which could affect the output of an IC.

In the performance metrics and co-design, hardware, digital, IC, software, analogue, and PCB are measured against their performance, power consumption, and cost. Electronic systems contain analogue and digital components as well as passive and active components. They are hosted in multilayer PCBs. Components are connected using wires in PCBs. Wires are placed close to each other and their interaction could affect the performance. The electronic systems contain both analogue and digital components within a single PCB or package.

Their interaction to each other could lead to unexpected and undesired behavior. The successive-approximation converter has more complex circuitry as compared to the digital-ramp ADC; it has a way shorter conversion time. These converters have a fixed value of conversion time that hardly depends on the rate of the analog input. SAR ADC ARCHITECTURE The SAR- ADC is quite useful for lower sampling rate and higher resolution. The main application for sigma-delta is found in the voice band, in some industrial measurements and audio applications.

The model is quite useful for data acquisition. It has resolution that ranges from 8 to 18 bits. It also has a sampling rate that ranges from 50 kHz to 50MHz. The most effective way to create Giga-rate application with up to 16 bit resolution. The architecture is composed of fewer blocks such as comparator, control logic and a converter. There are several merits and drawbacks associated with the SAR-ADC architecture and application. (i) It has a good speed to power ratio. (ii) It has a compact design when compared to flash ADC; this contributes to the cost effectiveness of an SAR-ADC. (iii) It is, however, limited in that it has one comparator in the architecture which works throughout the entire conversation process.

Any offset errors in the comparator reflect on the all conversion bits. (iv) The static parameter errors hardly affect the dynamic behavior of the SAR-ADC There is an engineering practice that ensures that all signals that are transmitted are received correctly as intended. This practice ensures that signals do not interfere with one another in a way to degrade reception[Wei11]. They ensure signal do not damage any device and that they do not pollute the electromagnetic spectrum. Losses degrade the signal amplitude, the signal edge rate, and ultimately it becomes a basic speed limiter of our current technology.

This causes severe problems for long buses and significant timing push-outs. APPLICATION OF ADC Analog to digital converters are used virtually everywhere as long as analog signal required to be processed, stored, or transported in digital form. The ADC usage are digital volt meters, cell phones, thermocouples, and digital oscilloscope. There are two processes in the ADC process namely: (i) Sampling and holding (ii) Quantizing and encoding There is a huge benefit in holding signals as it ensures the accuracy of the analog to digital conversion.

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