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345 results found, displaying items 221 - 240
"Ping-Pong" Configuration Increases System's Conversion Throughput
Traditionally, "ping-pong" configurations have been used with sample-and-hold circuits to increase throughput rates in data-acquisition systems. To increase throughput, this same technique can be implemented with standard analog-to-digital...
Solid-State Circuit Converts Temperature To Voltage
This circuit is a solid-state thermometer suitable for measuring temperatures from −40°C to 125°C (Fig. 1). By adjusting RZERO and RSCALE, the offset of the...
Bipolar Single-Supply Schmitt Trigger Extends DPM Range
There are some design complications encountered in applications that use single-supply circuitry to process an ac input signal. One drawback is that the signal often can’t be attenuated and level-shifted to fit within the supply range without...
Programmable Differential Amplifier Features Logarithmic-Type Gain
The circuit shown is a differential amplifier that not only offers programmability but also provides a logarithmic-type gain (Fig. 1). The traditional gain-setting resistors of the amplifier, R1 and R2, are...
Remove Large Common-Mode Signals Using Standard Op Amps
In many industrial applications, signals requiring analog-to-digital conversion ride on a large I common-mode signal of up to a few hundred volts. A familiar problem in these applications is removing this common-mode signal. Doing so enables...
Single-Rail Noninverting Schmitt Trigger Has Symmetrical Thresholds
A single-supply, inverting Schmitt trigger was detailed in a previous Idea For Design (“Comparator Features Symmetrical Thresholds,” by Samuel Kerem, Electronic Design, March 6, p. 124). The thresholds of this device remained symmetrical about a...
Differential Line Receivers Function As Analog Zero-Crossing Detectors
The RS-422 specification requires certain differential line receivers to be able to detect small differential voltages over a broad common-mode range. Within the recommended common-mode operating range of −7 to +7 V, these devices are...
Extend RMS-To-DC Converter's Range
This Idea For Design was originally published July 12, 1990. Comparator hysteresis can extend the dynamic range of ac signal measurement by autoranging an rms-to-dc converter. A...
Transimpedance Amp Employs Optically Isolated Digital Gain Control
Located atop 7500-ft. Table Mountain near Wrightwood, Calif., is the Jet Propulsion Lab Fourier transform ultraviolet spectrometer (FTUVS). This device uses sunlight as a spectral light source for the chemical assay of trace gases, such as ozone and...
Simple Current-Limiter And Power Switch Offer Overcurrent Protection
Many applications that use a single power supply need some type of overcurrent protection. Such a device will help prevent the entire system from shutting down in the event of a single fault or short circuit. The high-current switch Q1, driver Q3,...
Improved Photodiode Pre-Amp Uses Current-Feedback Amplifier
Asignificant problem with using photodiodes in fast applications like barcode scanners, CD-ROMs, and DVDs is that the diode has a high output capacitance. Combined with the input impedance of the pre-amp stage, this capacitance generally limits the...
Differential Receiver/Driver Overcomes Noisy Grounds
The line-driver circuit is used to provide a precise voltage from a source with a noisy ground reference to a remote load that also has a noisy ground reference (see the figure). In this application, the...
Positive Feedback Terminates Cables
This Idea For Design was originally published March 6, 1995. Positive feedback along with a series output resistor can provide a controlled output impedance from an op-amp circuit, with lower losses than would result from using an...
Simplify Isolated Temperature Sensing With Single-Wire Sensors
Galvanic isolation of sensors, such as temperature sensors, is required since these sensors are often mounted in "mechanically inconvenient" locations. "Mechanically inconvenient" often implies an electrically noisy environment, an environment where...
A Technique For Forming Long Time-Constants
The circuit in Figure 1 illustrates a classic use of a long time-constant. In this case, it’s an attack/release circuit that might be found in an automatic gain control. Resistor R1 and capacitor C1 form...
Photovoltaic Transimpedance Amp Is Programmed By Digital Pots
Millions of photovoltaic detectors are used to sense and measure radiant energy in every type of industrial, medical, consumer, and scientific instrumentation application. By properly selecting materials and structure, solid-state photovoltaics can...
Fast, Stable Wideband FET Amplifier
The design idea presented here is a gain-trimmable wideband FET amplifier with very good speed, high input impedance, and excellent dc stability under all conditions. Transistors Q1 and Q2 constitute a simple, high-speed FET input buffer....
Variable-Gain Active Band-Pass Filter Uses Only One Op Amp
Here’s an idea you’re not likely to find in the op-amp “cookbooks,” doubtless due to a worldwide conspiracy to sell more op amps. A single op-amp section can often “multitask” analog chores. This audio input stage combines low-pass,...
Emitter-Follower Boosts Linear Regulator's Output Current
Automotive electronics often require memory for saving system information or for user inputs (the settings on a car stereo, for example). Flash memory can do the job, but flash is expensive. DRAM memory reduces the cost, but DRAM requires an...
Composite Amp Had Low Noise, Drift
Typically, FET input operational amplifiers have desirable characteristics such as good frequency response, low input bias current, and low input bias-current noise compared to bipolar input amplifiers. On the other hand, bipolar...
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