3. Analog Digital C to Digital Analog C.pptx

Intro to ADC to DAC introduction

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1. DA and AD Conversion 1. Converters 2. Digital-to-Analog Architecture 3. Analog-to-Digital Architecture

2. 1. Converters Signals A voltage, current, or other quantity (Light for fiber optic) that conveys information. It may come from either real-time information or information-storage sources (FDD,CD, DVD, HDD, SSD). Analog signal Samples associated with discrete times separated by intervals called sampling intervals.

3. 1. Converters Analog signal is a form of electrical energy (voltage, current, or electromagnetic power) for which there is (ideally) a linear relationship b/w the electrical quantity and the value that the signal represents. Analog signal can be represented mathematically as a continuous function of time v(t) . Digital signal are invariably expressed as discrete numbers called samples associated with discrete times separated by intervals called sampling intervals .

4. 1. Converters Case 1: DAC They output an analog voltage that is a proportion of a reference voltage, the proportion based on the digital word applied. Case 2: ADC A digital representation of the analog voltage that is applied to the ADCs input is outputted. Digital input or output is arranged in words of varying widths, referred to as bits which are typically arranged in group of 4 called bytes . Case 1 Case 2

5. DA and AD Conversion 1. Converters 2. Digital-to-Analog Architecture 3. Analog-to-Digital Architecture

6. 2. Digital-to-Analog Architecture This converter is an electronic circuit which accepts a digital number at its input and produces a corresponding analog signal (usually a voltage) at the output. When data is in binary form 0’s and 1’s 0 = up to 0.8v 1 = 2v to 5v

7. 2. Digital-to-Analog Architecture DAC Method – Shift Keying This method is used to send computer information over transmission channels that require analog signals. This basic process is given the name “shift-keying” to differentiate it from the purely analog systems. Amplitude Shift Keying (ASK) Frequency Shift Keying (FSK) Phase Shift Keying (PSK)

8. 2. Digital-to-Analog Architecture DAC Method – Shift Keying DAC – Amplitude Shift Keying It is a technique in which carrier signal is analog and data to be modulated is digital, the amplitude of analog carrier signal is modified to reflect binary data. Note: The binary signal when modulated gives a zero value when the binary data represents 0 while gives the carrier output when data is 1. The frequency and phase of the carrier signal remain constant.

9. 2. Digital-to-Analog Architecture DAC Method – Shift Keying 2. Frequency Shift Keying In this technique in which the carrier signal is analog, and data to be modulated is digital. The amplitude of the analog carrier signal is modulated to reflect binary data. Note: The binary signal, when modulated, gives a zero value when the binary data represents 0 while gives the carrier output when data is 1. The frequency and phase of the carrier signal remain constant.

10. 2. Digital-to-Analog Architecture DAC Method – Shift Keying 3. DAC – Phase Shift Keying In this modulation the phase of the analog carrier signal is modified to reflect binary data. Note: The amplitude and frequency of the carrier signal remain constant.