professional analog to digital video converter

Professional analog to digital video converter series#

A longer discharge time results in a higher count Dual Slope Converter Advantages Input signal is averaged Greater noise immunity than other ADC types High accuracy Disadvantages Slow High precision external components required to achieve accuracy 8ĩ Digital-to-Analog Conversion A-D converter.ppt Digital-to-Analog Conversion When data is in binary form, the 0's and 1's may be of several forms such as the TTL form where the logic zero may be a value up to 0.8 volts and the 1 may be a voltage from 2 to 5 volts. for 8 bits, 256 comparators needed Dual Slope Converter V in t FIX t meas t The sampled signal charges a capacitor for a fixed amount of time By integrating over time, noise integrates out of the conversion Then the ADC discharges the capacitor at a fixed rate with the counter counts the ADC s output bits. ADC Output 7Ĩ Flash Advantages Simplest in terms of operational theory Most efficient in terms of speed, very fast limited only in terms of comparator and gate propagation delays Disadvantages Lower resolution Expensive For each additional output bit, the number of comparators is doubled i.e. The priority encoder generates a binary number based on the highest-order active input, ignoring all other active inputs. The comparator outputs connect to the inputs of a priority encoder circuit, which produces a binary output 6ħ Flash ADC Circuit How Flash Works As the analog input voltage exceeds the reference voltage at each comparator, the comparator outputs will sequentially saturate to a high state.

Professional analog to digital video converter series#

A/D Converter Types By Danny Carpenter Converters Flash ADC Dual Slope (integrating) ADC Successive Approximation ADC Flash ADC Consists of a series of comparators, each one comparing the input signal to a unique reference voltage.

4Ħ Overall Better Accuracy Increasing both the sampling rate and the resolution you can obtain better accuracy in your AD signals. increasing the sampling rate which increases the maximum frequency that can be measured. Output States Output Binary Equivalent Accuracy of A/D Conversion There are two ways to best improve accuracy of A/D conversion: increasing the resolution which improves the accuracy in measuring the amplitude of the analog signal. Analog quantization size: Q=(Vmax-Vmin)/N = (10V 0V)/8 = 1.25V Encoding Here we assign the digital value (binary number) to each state for the computer to read. (How did we get 1.25V? See next slide ) Output States Discrete Voltage Ranges (V)Ĥ Quantizing The number of possible states that the converter can output is: N=2 n where n is the number of bits in the AD converter Example: For a 3 bit A/D converter, N=2 3 =8. Separate them into a set of discrete states with 1.25V increments. Examples: Light switch can be either on or off Door to a room is either open or closed Real world (lab) is analog Computer (binary) is digital V Bin From: James Mackey Examples of A/D Applications Microphones - take your voice varying pressure waves in the air and convert them into varying electrical signals Strain Gages - determines the amount of strain (change in dimensions) when a stress is applied Thermocouple temperature measuring device converts thermal energy to electric energy Voltmeters Digital Multimeters 2ģ Just what does an A/D converter DO? Converts analog signals into binary words Analog Digital Conversion 2-Step Process: Quantizing - breaking down analog value is a set of finite states Encoding - assigning a digital word or number to each state and matching it to the input signal Step 1: Quantizing Example: You have 0-10V signals. For digital computers, we refer to binary states, 0 and 1. 1Ģ Digital Signals Digital Signals have only two states. Digital? Examples of ADC Applications Types of A/D Converters Successive Approximation ADC Analog Signals Analog signals directly measurable quantities in terms of some other quantity Examples: Thermometer mercury height rises as temperature rises Car Speedometer Needle moves farther right as you accelerate Stereo Volume increases as you turn the knob. 1 Analog to Digital Converters By: Byron Johns, Danny Carpenter Stephanie Pohl, Harry Bo Marr (unless otherwise marked) Presentation Outline Introduction: Analog vs.