Fundamentals of Digital Electronics - Lab 8

Analog-to-Digital Converters, Chuyển đổi analog-to-kỹ thuật số, được gọi là bộ chuyển đổi A / D (đọc là A đến D-chuyển đổi) hoặc ADC, là thành phần quan trọng thứ hai để bắc cầu thế giới analog và kỹ thuật số. ADC là cơ sở của voltmeters kỹ thuật số, kỹ thuật số multimeters, phân tích đa kênh, dao động, và các công cụ khác. Có rất nhiều ADC thiết kế khác nhau, trong đó đoạn đường nối, theo dõi, và chuyển đổi xấp xỉ liên tiếp là phổ biến. Phòng thí nghiệm này xem xét các đoạn. | Lab 8 Analog-to-Digital Converters Part I The analog-to-digital converter known as the A D converter read as A-to-D converter or the ADC is the second key component to bridging the analog and digital worlds. The ADC is the basis of digital voltmeters digital multimeters multichannel analyzers oscilloscopes and many other instruments. There are many different ADC designs of which the ramp tracking and successive approximation converters are common. This lab looks at the ramp and tracking A D converters. Purpose of the Analog-to-Digital Converter The purpose of an ADC converter is to produce a digital binary number that is proportional to an analog input signal. The fundamental conversion process is shown in the following diagram. Figure 8-1. Symbolic Design for an 8-Bit Analog-to-Digital Converter A counter creates a test binary sequence and its digital output is converted into an analog voltage using a digital-to-analog converter. The DAC is a basic element of many ADC circuits and was discussed in Lab 7. This is a good time to review its operation if you are not familiar with the DAC. The test voltage is then compared with the input signal. If the input signal is larger than the test signal the counter is increased to bring the test signal closer to the input level. If the input signal is smaller than the test signal the counter is decreased to bring the test signal closer to the input level. The National Instruments Corporation 8-1 Fundamentals of Digital Electronics Lab 8 Analog-to-Digital Converters Part I process continues until the comparator changes sign at which time the test level will be within one count of the input level. Increasing the number of bits of the counter and DAC increases the conversion resolution. The Ramp ADC The ramp ADC uses a binary counter and digital-to-analog converter to generate a ramp test waveform. In this demonstration an 8-bit binary up counter Binary together with the 8-bit DAC introduced in the last lab .