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Analog to Digital Circuits
Analog to Digital Circuits
BIOS interrupt performs A/D conversion
Most A/D-conversion techniques use dedicated hardware, usually a single-chip IC. The flexible conversion technique allows you to use successive-approximation, ramp-type, or other converters by writing the appropriate control software. The design in Figure 1 uses a PC`s parallel port for interface to a DAC and a special BIOS interrupt (INT 1CH)...
Simple circuit provides precision ADC interface
Real-world measurement requires the extraction of weak signals from noisy sources. High common-mode voltages are often present even in differential measurements. The usual approach to this problem is to use an op amp or an instrumentation amplifier and then perform some type of lowpass-filtering to reduce the background noise level. The problems...
Circuit provides reference for multiple ADCs
The achievable accuracy for systems with multiple ADCs depends directly on the reference voltages applied to the ADCs. Medical- ultrasound- imaging systems, for example, commonly include a large number of ADCs in the system`s beam-former electronics, with the ADCs usually organized in groups of 16, 24, 32, and so on. To obtain maximum beam...
Current-input ADC measures voltages
A practical realization of a spread-spectrum technique lowers a µP`s clock-related EMI by approximately 4 dB without the drawbacks associated with modulation (Figure 1). The spread-spectrum technique is a popular method to reduce µP-clock-related EMI (Reference 1). Using this method, the µP`s clock frequency constantly shifts around and creates...
Defining and Testing Dynamic Parameters in High-Speed ADCs, Part 1
The first part of this article series discusses commonly known definitions most crucial for high-speed data converters (in this case analog-to-digital converter or short ADCs) used in communications, instrumentation and data acquisition applications. The purpose of this article is to help the reader gain a better understanding of common...
Demystifying Sigma-Delta ADCs
This in-depth article covers the theory behind a Delta-Sigma analog-to-digital converter (ADC). It specifically focuses on the difficult to understand key digital concepts of over-sampling, noise shaping, and decimation filtering. A description of new converter, the MAX1402, and several applications for Delta-Sigma converters are included....
Differential amp drives high-speed ADC
The schematic in Figure 1 is the discrete-element version of an A/D-converter drive circuit. The circuit converts a single-ended input to a differential output. The ADC`s reference voltage determines the common-mode range of the differential outputs. The circuit contains two AD9631 amplifiersone connected in noninverting mode, and the other...
Dual 8-bit ADCs provide pseudo high resolution
By using two 8-bit ADC channels for the same signal, the technique in Figure 1 can accommodate both conditions. One channel, which the controller uses for fast motion, reads the input directly and adds four 0 LSBs for a 12-bit result. The second channel reads the signal amplified by 16 with four 0 MSBs. The amplification gives this channel the...
Dynamic Testing of High-Speed ADCs, Part 2
Analog-to-digital converters (ADCs) represent the link between analog and digital worlds in receivers, test equipment and other electronic devices. As outlined in Part 1 of this article series, a number of key dynamic parameters provide an accurate correlation of the dynamic performance to be expected from a given ADC. Part 2 of this article...
Frequency dithering enhances high-performance ADCs
Since the late 1970s, designers have successfully improved the effective resolution and spurious performance of A/D converters by adding ditheruncorrelated noiseto a converter`s input and then using DSP techniques to average out noise from the converted data. The most common dithering method adds random-amplitude noise to an A/D converter`s...
Hardware histogram speeds ADC test
The circuit of Figure 1 shows how you can configure a FIFO memory, a static SRAM, and a bus register to generate fast hardware histograms for linearity tests and still allow straight data acquisition for other tests. The main purpose of the FIFO memory is to collect data at the speed of the DUT (device under test), because, with all the...
Improved amplifier drives differential-input ADCs
ADCs with differential inputs are becoming increasingly popular. This popularity isn`t surprising, because differential inputs in the ADC offer several advantages: good common-mode noise rejection, a doubling of the available dynamic range without doubling the supply voltage, and cancellation of even-order harmonics that accrue with a...
INL/DNL Measurements for High-Speed Analog-to-Digital Converters
Manufacturers have recently introduced high-performance analog-to-digital converters (ADCs) that feature outstanding static and dynamic performance. You might ask, "How do they measure this performance, and what equipment is used?" The following discussion should shed some light on techniques for testing two of the accuracy parameters important...
Matched offsets put signals into ADC`s range
This circuit was designed for measuring the current from a set of power trackers on the Iowa State University Solar Car, the PrISUm Phoenix. The power trackers provide impedance matching between the solar array and the main electrical bus on the car. Because the current shunt for the power trackers is on the low side and the ground reference...
Micropower MSOP 10-Bit ADC Samples at 500ksps
The LTC®1197/LTC1199 10-bit serial ADCs offer small size, low power operation and fast sample rates with good AC and DC performance. These parts are ideal for low power, high speed and/or compact designs. This Design Note discusses the features and performance that make the LTC1197/LTC1199 excellent choices for such new designs.
New 14-Bit, 800ksps ADC Upgrades 12-Bit Systems with 81.5dB SINAD, 95dB SFDR
The new 14-bit, 800ksps LTC®1419 enhances new communications, spectral analysis, instrumentation and data acquisition applications by providing an upgrade path to users of 12-bit converters. It provides outstanding 81.5dB SINAD (signal-to-noise and distortion ratio) and 95dB SFDR (spurious-free dynamic range) for frequency-domain applications,...
New 16-Bit, 100ksps A/D Converter Runs on 5V Supply
The LTC®1605 is a new 16-bit, 100ksps ADC from Linear Technology. Its outstanding DC accuracy and ±10V analog input range are ideal for industrial control and instrumentation applications. Its simple I/O, low power and high performance make it easy to design into applications requiring wide dynamic range and high resolution.
New 500ksps and 600ksps ADCs Match Needs of High Speed Applications
Combining high speed analog-to-digital conversion with low power dissipation, the 500ksps LTC®1278 and 600ksps LTC1279 12-bit ADCs solve major challenges confronting designers of high speed systems: conversion performance, power dissipation, circuit board real estate, complexity, and cost. Applications for the LTC1278/LTC1279 include telecom,...
New 5V and 3V, 12-Bit ADCs Sample at 300kHz on 75mW and 140kHz on 12mW
Four new sampling A/D converters from Linear Technology stand out above the rest of the crowd. These new 5V and 3V 12-bit ADCs offer the best speed/power performance available today (see Figure 1). They also provide precision reference, internally trimmed clock, and fast sample-andhold. With additional features such as single supply operation...
Pipeline ADCs Come of Age
The following article takes the knowledge of advantages and disadvantages of the pipeline architecture and compares its features with four of the most popular architectures (flash, dual-slope, sigma-delta, and successive approximation) for analog-to-digital converters (ADCs). The paper concludes with an applications example for CCD imaging and...
Rearranged reference helps ADC measure its own supply voltage
If you use an ADC to monitor a system`s power-supply voltage, you may encounter situations in which the supply voltage exceeds the ADC`s reference voltage (Figure 1). However, the ADC`s input voltage cannot exceed its reference voltage. You can use an external resistive divider to bring the supply voltage within the ADC`s input range, but even...
Temperature-measurement scheme uses IR sensor and sigma-delta ADC
Many noncontact temperature-measurement systems use infrared sensors, such as thermopiles, which can detect small amounts of heat radiation. Biomedical thermometers that measure the temperature of an ear or a temple use noncontact temperature measurement, as do automotive-HVAC systems that adjust temperature zones based on the body temperature...
Two wires control SPI high-speed ADC
Most current microprocessors, DSPs, and field-programmable gate arrays integrate hardware and software resources that support either or both of two common interface standardsSPI (serial-peripheral interface) and I2C (inter-IC)/SMBus. Both two-wire-interface standards suffer from a few crucial disadvantages. For example, I2C`s throughput rates...
Understanding Flash ADCs
Flash analog-to-digital converters, also known as parallel ADCs, are the fastest way to convert an analog signal to a digital signal. Flash ADCs are ideal for applications requiring very large bandwidth, however, they typically consume more power than other ADC architectures and are generally limited to 8-bits resolution. Flash ADCs are made by...
Understanding Integrating ADCs
Integrating analog-to-digital converters (ADCs) provide high resolution analog-to-digital conversions, with good noise rejection. These ADCs are ideal for digitizing low bandwidth signals, and are used in applications such as digital multi-meters and panel meters. They often include LCD or LED drivers and can be used stand alone without a...
Single-Ended, Pseudo-Differential and Fully-Differential ADC Inputs
Many of today`s instrumentation and process control applications convert the analog output of a sensor for processing and/or storage using an analog-to-digital converter (ADC). For voltage input ADCs, three different input structure types exist: Single-Ended, Pseudo-Differential and Fully-Differential. This tutorial explains the differences,...
Binary to Decimal Converter Circuit
The project is designed as a learning toy with a reward for determining the correct answer (see Figure 1). The object is to represent a random number, from 1 to 255, in binary form by using eight LEDs. The user enters the decimal form of the number using a keypad. The users guess is displayed on an LCD as the guess is entered. Once the guess is...
Computer Serial Port interface
Here is an inexpensive way to get slow-moving analog data directly into a spreadsheet on your computer! A simple circuit connects to a serial port and a short Qbasic program gathers and saves 12 bit data to a file. A spreadsheet automatically retrieves the file and displays the data in real time. Once the data is in the spreadsheet, the full...
Color organ with PIC16F84
Flash-back to the 60's with this 5 channel unit with up to 100 watts per channel. This unit uses a PIC16F84 with an 8 bit A/D. The signal from both stereo channels is combined and digitized. Each of 5 frequency bands is processed using a 16 point FFT. Then the level of each channel is output as PWM (pulse width modulation) to a set of solid...
A/D converter 16Bit with LCD and PIC18F2550
The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the adjustment of the potentiometer. PIC used in this example come with a 10 bit ADC. In the...
Frequency meter 1KHz to 1MHz
This circuit is a frequency meter, low cost. It covers region 1HZ until 1MHZ. The IC1 schmitt trigger that it regulates the signal of entry and him changes in reasonable level suitable for the IC2-3-4. With the tenth pulse in the entry of IC2/1, is produced a pulse '' carry '' in the IC3/5. The same moment the IC2 causes the depiction in the...
10 Bit analog to digital converter
Study the Analog to Digital capabilities of Atmel ATtiny26. This tiny but mighty IC is really a miracle. One special thing is the internal 10-inputs multiplexed ADC circuit which can covert analog voltages to bytes. This check circuit uses only 3 inputs. Of course you can may changes to use more inputs. I used the AVRISP in-circuit programmer to...
Digital to Analog Circuits
Data Logging Circuits
Data Bus Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial