10 Important Pattern Generator Terms

Pattern Generator

A pattern generator is an electronic diagnostic device that is used to produce varying stimuli in the form of electrical waveforms. The primary objective of a pattern generator is the effective stimulation of a given device's inputs. When used in conjunction with a logic analyzer, the pattern generator allows its user to test an electronic appliance for detectable bugs more effectively than with the logic analyzer alone. The outputs produced by the pattern generator can be used as inputs to the UUT, or unit under test. The resulting response from the UUT then acts as a trigger for the logic analyzer.

Bipolar Junction Transistor (BJT)

A bipolar junction transistor (abbreviated as BJT) is an active semiconductor device made of doped materials and is characterized by three-terminal construction. Its function lies in the amplification of electric currents. Transistors of this type operate using both electrons and holes (hence the name "bipolar"), whereas unipolar transistors operate using only one carrier type when charging flow.

Breakdown Voltage

Breakdown voltage (also called Zener voltage) refers to the minimum reverse voltage required to make a diode conduct in reverse. More generally, it is the voltage measured at a specific current in a diode's breakdown region or the voltage at which a breakdown will potentially occur in an electronic device.

Curve Tracer

A curve tracer is an electronic testing device used to troubleshoot circuits and to analyze components. It assesses the characteristics of numerous devices, including diodes and transistors. Function includes the application of a varying voltage to the main terminals of the instrument being tested. While this swept voltage is applied, a measurement is taken to determine the amount of current that flows through the device. The circuit traces the current and compares it to the voltage curve using an oscilloscope. The curve tracer includes integrated sources of voltage and current that are used to stimulate the instrument being tested.

Data Delay

Data delay is a configuration feature on certain types of electronic testing equipment. It is used to adjust the acquisition and generation of data during a given testing period. By shifting the clock position to a specific value using the data delay feature, the user can ensure more accurate data sampling. This is especially important as the speed of a digital signal under test increases, as data acquisition at a higher clock rate yields smaller clock periods and, therefore, increased margin for error and false data.

Data Rate

In computing and telecommunications, data rate refers to the speed at which data (or digital information in the form of binary digits) is transmitted or processed per unit of time. Data rate is most commonly expressed in bits per second (bps), kilobits per second (Kbps) or megabits per second (Mbps).

Delayed Non-Return to Zero (DNRZ)

In the realm of telecommunications, delayed non-return to zero (abbreviated as DNRZ) refers to the line of binary code that is formatted to produce a specific bi-level signal. In this configuration, a zero results in no alteration of the signal's level unless a second zero follows it immediately. When this occurs, a change to the other level occurs, but only at the end of the bit period. A one results in a change from one level to the next in the middle of the period. DNRZ inherently contains less low-frequency energy than a signal formatted to a non-return to zero configuration.

Diode

A diode is a component of electronic instrumentation that allows current to flow in only one direction at a time and prevents that current from flowing in the opposite direction. A diode is, in part, comprised of two electrodes (an anode and a cathode) that act similarly to miniature semiconductors. The cathode is usually negatively charged in order to allow current to flow efficiently through the diode, as it will not flow at all if the voltage of the cathode and anode are charged to a similar voltage.

I-V Curve

I-V curve (also called the current-voltage curve) refers to the relationship between an electrical current and a correspondent voltage. It is most often expressed via chart or graph. This information can be used to inform the user of the voltage dependence of the specific channel under test.

Jitter

Jitter refers to a brief, impermanent variation of a digital signal's optimum sampling instants (or other significant instants) from their ideal locations in time. Jitter can more simply be described as a timing error within a given system. Unresolved jitters can potentially lead to more severe data errors.

Leakage Current

Leakage current refers to the undesirable loss of electrical current in transistors or other electronic equipment. In semiconductors, leakage of current or electrons occurs at the level of the transistor and is more common in especially minute components. When current is lost due to leakage, semiconductors inherently require more energy to operate and generate more heat as they attempt to bolster performance. Heat caused by current leakage can lead to failure of circuits and compromised functionality.

Looping Compensation

When a control feedback loop causes unintended and undesirable oscillation, loop compensation is employed to stop or prevent it. It increases stability within the circuit for enhanced performance.

Metal-Oxide Semiconductor Field Effect Transistor (MOSFET)

The metal-oxide semiconductor field effect transistor (abbreviated as MOSFET) is a commonly utilized semiconductor device that amplifies electronic signals. A semiconductor is comprised of synthetic materials that are not as conductive as the materials of a conductor, nor as insulating as materials that do not conduct electricity at all. When a specific amount of voltage is administered across the MOSFET system, it modifies the dispersion of electrical charges within the semiconductor. An important feature of the MOSFET is that its design allows for precise control of conduction and insulation. This is possible due to the construction of the device as well as the type of silicon (or other material) used to manufacture it.

Non-Return to Zero (NRZ)

Non-return to zero (abbreviated as NRZ) refers to a line of binary code in which no neutral condition or rest state exists. Ones are most commonly denoted by a positive voltage while zeroes are denoted by another significant condition, most commonly a value of negative voltage. The pulses produced have more inherent energy than a return to zero line of code. Unlike RZ code, NRZ is not self-clocking. This means that the signal must be synchronized by some other means in order to prevent bit slip.

Parametric Characterization

Parametric characterization testing offers detailed parameter analysis of various electronic testing devices (including curve tracers). Specially manufactured hardware and software combine to provide the user of the parametric testing device to characterize complex semiconductor processes and instruments easily and effectively. An important portion of parametric characterization is the verification and analysis of parametric failure. This term refers to a device's inability to meet the electrical requirements for a measurable attribute (for example, leakage current) that does not immediately affect the functionality of the device. Therefore a parametric failure may occur even if no issue with functionality is detected.

Pattern Depth/Length

Pattern depth and length refer to the distance interval and spacing between the spectral lines of a signal. Depth and length are adjustable components of pattern generators and spectrum analyzing devices. Electromagnetic interference that causes problems during testing can be reduced or eliminated by adjusting pattern depth and length or data rate.

Peak Power

Peak power refers to the maximum amount of power in a pulsed signal. Often, pulses are characterized by short pulse duration. This can inherently lead to incredibly high peak power in pulses that are relatively low in energy. For moderately long pulses, the peak power can be determined more directly.

Pseudorandom Binary Sequence (PRBS)

Pseudorandom Binary Sequence (abbreviated as PRBS) refers to a pattern sequence comprised of random bits of one and zero. It is used as a pattern for testing the functionality of various transmitters and similar equipment. Pseudorandom binary sequences can be produced using a pattern generator.

Return to Zero (RZ)

Return to zero (abbreviated as RZ), in the realm of telecommunications, refers to a line of code in which a signal rapidly decreases back to zero between each pulse of the signal. The return to zero action will occur even in situations in which multiple zeroes or ones appear simultaneously in the signal. Because the signal is self-clocking, the need for separate circuits and extra logic are eliminated. However, this feature does cause the signal to use twice as much bandwidth as would a signal formatted with a non-return to zero (NRZ) configuration.

Sampling Rate

Sampling rate (also known as sampling frequency) refers to the quantity of samples captured or defined from a continuous signal within a given amount of time. Usually measured in hertz (Hz), sampling rate determines the range of frequencies that can be reproduced in digital wave form.

Voltage/Current Sourcing

Voltage or current sourcing refers to the drawing of constant and direct power into or out of a device, specifically through a high-impedance node or terminal.

Waveform Averaging

Waveform averaging (used to reveal a waveform's spectrum and other characteristics amid interference or noise) works by triggering data acquisition at precise moments within a repetitive production of a signal.