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A pulse generator is either an electronic circuit or a piece of electronic test equipment used to generate rectangular pulses. Pulse generators are used primarily for working with digital circuits; related function generators are used primarily for analog circuits.
Simple bench pulse generators usually allow control of the pulse repetition rate (frequency), pulse width, delay with respect to an internal or external trigger and the high- and low-voltage levels of the pulses. More sophisticated pulse generators may allow control over the rise time and fall time of the pulses. Pulse generators are available for generating output pulses having widths (duration) ranging from minutes to under 1 picosecond.
Pulse generators are generally voltage sources, with true current pulse generators being available only from a few suppliers.
Pulse generators may use digital techniques, analog techniques, or a combination of both techniques to form the output pulses. For example, the pulse repetition rate and duration may be digitally controlled but the pulse amplitude and rise and fall times may be determined by analog circuitry in the output stage of the pulse generator. With correct adjustment, pulse generators can also produce a 50% duty cycle square wave. Pulse generators are generally single-channel, providing one frequency, delay, width and output.
Light pulse generators are the optical equivalent to electrical pulse generators with rep rate, delay,width and amplitude control. The output in this case is light, typically from a LED or laser diode.
A new family of pulse generators can produce multiple channels of independent widths and delays and independent outputs and polarities. Often called digital delay/pulse generators, the newest designs even offer differing repetition rates with each channel. These digital delay generators are useful in synchronizing, delaying, gating and triggering multiple devices, usually with respect to one event. One is also able to multiplex the timing of several channels onto one channel in order to trigger or even gate the same device multiple times.
A new class of pulse generator offers both multiple input trigger connections and multiple output connections. Multiple input triggers allow experimenters to synchronize both trigger events and data acquisition events using the same timing controller.
In general, generators for pulses with widths over a few microseconds employ digital counters for timing these pulses, while widths between approximately 1 nanosecond and several microseconds are typically generated by analog techniques such as RC (resistor-capacitor) networks or switched delay lines.
Pulse generators capable of generating pulses with widths under approximately 100 picoseconds are often termed as "microwave pulsers" and typically generate these ultra-short pulses using Step recovery diode (SRD) or Nonlinear Transmission Line (NLTL) methods (for example ). Step Recovery Diode pulse generators are inexpensive, but typically require several volts of input drive level and have a moderately high level of random jitter (usually undesirable variation in the time at which successive pulses occur).
NLTL-based pulse generators generally have lower jitter, but are more complex to manufacture and do not suit integration in low-cost monolithic ICs. A new class of microwave pulse generation architecture, the RACE (Rapid Automatic Cascode Exchange) pulse generation circuit [1] [2] is implemented using low-cost monolithic IC technology and can produce pulses as short as 1 picosecond and repetition rates exceeding 30 billion pulses per second. These pulsers are typically used in military communications applications and low-power microwave transceiver ICs. Such pulsers, if driven by a continuous frequency clock, will act as microwave comb generators, having output frequency components at integer multiples of the pulse repetition rate, and extending to well over 100 gigahertz (for example [ permanent dead link ]).
Pulses can be injected into a device that is under test and used as a stimulus, clock signal, or analyzed as they progress through the device, confirming the proper operation of the device or pinpointing a fault in the device. Pulse generators are also used to drive devices such as switches, lasers and optical components, modulators, intensifiers, and resistive loads. The output of a pulse generator may also be used as the modulation signal for a signal generator. Non-electronic applications include those in material science, medical, physics, and chemistry.
In electronics, an analog-to-digital converter is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide an isolated measurement such as an electronic device that converts an analog input voltage or current to a digital number representing the magnitude of the voltage or current. Typically the digital output is a two's complement binary number that is proportional to the input, but there are other possibilities.
In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal. In clock recovery applications it is called timing jitter. Jitter is a significant, and usually undesired, factor in the design of almost all communications links.
A signal generator is one of a class of electronic devices that generates electrical signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typically used in designing, testing, troubleshooting, and repairing electronic or electroacoustic devices, though it often has artistic uses as well.
A power inverter, inverter, or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opposite of rectifiers which were originally large electromechanical devices converting AC to DC.
A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned over some range. It is a necessary component in any tunable radio transmitter and in receivers that work by the superheterodyne principle. The oscillator controls the frequency to which the apparatus is tuned.
A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The applied input voltage determines the instantaneous oscillation frequency. Consequently, a VCO can be used for frequency modulation (FM) or phase modulation (PM) by applying a modulating signal to the control input. A VCO is also an integral part of a phase-locked loop. VCOs are used in synthesizers to generate a waveform whose pitch can be adjusted by a voltage determined by a musical keyboard or other input.
In electronic instrumentation and signal processing, a time-to-digital converter (TDC) is a device for recognizing events and providing a digital representation of the time they occurred. For example, a TDC might output the time of arrival for each incoming pulse. Some applications wish to measure the time interval between two events rather than some notion of an absolute time.
A single-photon avalanche diode (SPAD), also called Geiger-mode avalanche photodiode is a solid-state photodetector within the same family as photodiodes and avalanche photodiodes (APDs), while also being fundamentally linked with basic diode behaviours. As with photodiodes and APDs, a SPAD is based around a semi-conductor p-n junction that can be illuminated with ionizing radiation such as gamma, x-rays, beta and alpha particles along with a wide portion of the electromagnetic spectrum from ultraviolet (UV) through the visible wavelengths and into the infrared (IR).
In electrical engineering, a function generator is usually a piece of electronic test equipment or software used to generate different types of electrical waveforms over a wide range of frequencies. Some of the most common waveforms produced by the function generator are the sine wave, square wave, triangular wave and sawtooth shapes. These waveforms can be either repetitive or single-shot. Another feature included on many function generators is the ability to add a DC offset. Integrated circuits used to generate waveforms may also be described as function generator ICs.
An IMPATT diode is a form of high-power semiconductor diode used in high-frequency microwave electronics devices. They have negative resistance and are used as oscillators and amplifiers at microwave frequencies. They operate at frequencies of about 3 and 100 GHz, or higher. The main advantage is their high-power capability; single IMPATT diodes can produce continuous microwave outputs of up to 3 kilowatts, and pulsed outputs of much higher power. These diodes are used in a variety of applications from low-power radar systems to proximity alarms. A major drawback of IMPATT diodes is the high level of phase noise they generate. This results from the statistical nature of the avalanche process.
A microwave power meter is an instrument which measures the electrical power at microwave frequencies typically in the range 100 MHz to 40 GHz.
A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems. There are several different types of video signal generators in widespread use. Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses or sync words. Generators of composite video signals will also include a colorburst signal as part of the output.
In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage. The term dates from the first three decades of radio (1888–1918). Unlike modern radio stations which transmit sound on an uninterrupted carrier wave, early radio stations transmitted information by radiotelegraphy. The transmitter was switched on and off to produce long or short periods of radio waves, spelling out text messages in Morse code. Therefore, early radio receivers could reproduce the Morse code "dots" and "dashes" by simply distinguishing between the presence or absence of a radio signal. The device that performed this function in the receiver circuit was called a detector. A variety of different detector devices, such as the coherer, electrolytic detector, magnetic detector and the crystal detector, were used during the wireless telegraphy era until superseded by vacuum tube technology.
A pulse per second is an electrical signal that has a width of less than one second and a sharply rising or abruptly falling edge that accurately repeats once per second. PPS signals are output by radio beacons, frequency standards, other types of precision oscillators and some GPS receivers. Precision clocks are sometimes manufactured by interfacing a PPS signal generator to processing equipment that aligns the PPS signal to the UTC second and converts it to a useful display. Atomic clocks usually have an external PPS output, although internally they may operate at 9,192,631,770 Hz. PPS signals have an accuracy ranging from 12 picoseconds to a few microseconds per second, or 2.0 nanoseconds to a few milliseconds per day based on the resolution and accuracy of the device generating the signal.
A digital delay generator is a piece of electronic test equipment that provides precise delays for triggering, syncing, delaying, and gating events. These generators are used in many experiments, controls, and processes where electronic timing of a single event or multiple events to a standard timing reference is needed. The digital delay generator may initiate a sequence of events or be triggered by an event. What differentiates it from ordinary electronic timing is the synchronicity of its outputs to each other and the initiating event.
An oscilloscope is a type of electronic test instrument that graphically displays varying voltages of one or more signals as a function of time. Their main purpose is capturing information on electrical signals for debugging, analysis, or characterization. The displayed waveform can then be analyzed for properties such as amplitude, frequency, rise time, time interval, distortion, and others. Originally, calculation of these values required manually measuring the waveform against the scales built into the screen of the instrument. Modern digital instruments may calculate and display these properties directly.
A digital pattern generator is a piece of electronic test equipment or software used to generate digital electronic stimuli. Digital electronics stimuli are a specific kind of electrical waveform varying between two conventional voltages that correspond to two logic states. The main purpose of a digital pattern generator is to stimulate the inputs of a digital electronic device. For that reason, the voltage levels generated by a digital pattern generator are often compatible with digital electronics I/O standards – TTL, LVTTL, LVCMOS and LVDS, for instance.
The history of the oscilloscope was fundamental to science because an oscilloscope is a device for viewing waveform oscillations, as of electrical voltage or current, in order to measure frequency and other wave characteristics. This was important in developing electromagnetic theory. The first recordings of waveforms were with a galvanometer coupled to a mechanical drawing system dating from the second decade of the 19th century. The modern day digital oscilloscope is a consequence of multiple generations of development of the oscillograph, cathode-ray tubes, analog oscilloscopes, and digital electronics.
This glossary of electrical and electronics engineering is a list of definitions of terms and concepts related specifically to electrical engineering and electronics engineering. For terms related to engineering in general, see Glossary of engineering.
In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier's characteristics and performance. The first three classes are related to the time period that the active amplifier device is passing current, expressed as a fraction of the period of a signal waveform applied to the input. This metric is known as conduction angle (θ). A class A amplifier is conducting through the entire period of the signal (θ=360°); Class B only for one-half the input period (θ=180°), class C for much less than half the input period (θ<180°). Class D amplifiers operate their output device in a switching manner; the fraction of the time that the device is conducting may be adjusted so a pulse-width modulation output can be obtained from the stage.
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