In
digital circuitDigital electronics are systems that represent signals as discrete levels, rather than as a continuous range. In most cases the number of states is two, and these states are represented by two voltage levels: one near to zero volts and one at a higher level depending on the supply voltage in use...
s, a
runt pulse is a narrow
pulseIn signal processing, the term pulse has the following meanings:#A rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value....
that,
due to non-zero
riseIn electronics, when describing a voltage or current step function, rise time refers to the time required for a signal to change from a specified low value to a specified high value. Typically, these values are 10% and 90% of the step height...
and
fallIn electronics, fall time is the time required for the amplitude of a pulse to decrease from a specified value to another specified value...
times of the signal, does not reach a valid
high or low level. A runt pulse may occur when switching between
asynchronous
clocksAlthough the word signal has a number of other meanings, the term is here used for "transmitted energy that can carry information." In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is...
; or as the result of a
race conditionA race condition or race hazard is a flaw in an electronic system or process whereby the output and/or result of the process is unexpectedly and critically dependent on the sequence or timing of other events...
in which a signal takes two separate paths through a circuit, which may have different delays, and is then recombined to form a
glitchA glitch is a short-lived fault in a system. The term is particularly common in the computing and electronics industries, and in circuit bending, as well as among players of video games, although it is applied to all types of systems including human organizations and nature...
; or when the output of a
flip-flopIn digital circuits, a flip-flop is a term referring to an electronic circuit that has two stable states and thereby is capable of serving as one bit of memory...
becomes
metastableMetastability in electronics is the ability of an unstable equilibrium electronic state to persist for an indefinite period in a digital system. Note this definition does not guarantee all of the properties that are sometimes demanded for a metastable state in statistical mechanics...
.
Some
oscilloscopeAn oscilloscope is a type of electronic test instrument that allows signal voltages to be viewed, usually as a two-dimensional graph of one or more electrical potential differences plotted as a function of time or of some other voltage...
s provide a method for triggering on runt pulses.
In
digital circuitDigital electronics are systems that represent signals as discrete levels, rather than as a continuous range. In most cases the number of states is two, and these states are represented by two voltage levels: one near to zero volts and one at a higher level depending on the supply voltage in use...
s, a
runt pulse is a narrow
pulseIn signal processing, the term pulse has the following meanings:#A rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value....
that,
due to non-zero
riseIn electronics, when describing a voltage or current step function, rise time refers to the time required for a signal to change from a specified low value to a specified high value. Typically, these values are 10% and 90% of the step height...
and
fallIn electronics, fall time is the time required for the amplitude of a pulse to decrease from a specified value to another specified value...
times of the signal, does not reach a valid
high or low level. A runt pulse may occur when switching between
asynchronous
clocksAlthough the word signal has a number of other meanings, the term is here used for "transmitted energy that can carry information." In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is...
; or as the result of a
race conditionA race condition or race hazard is a flaw in an electronic system or process whereby the output and/or result of the process is unexpectedly and critically dependent on the sequence or timing of other events...
in which a signal takes two separate paths through a circuit, which may have different delays, and is then recombined to form a
glitchA glitch is a short-lived fault in a system. The term is particularly common in the computing and electronics industries, and in circuit bending, as well as among players of video games, although it is applied to all types of systems including human organizations and nature...
; or when the output of a
flip-flopIn digital circuits, a flip-flop is a term referring to an electronic circuit that has two stable states and thereby is capable of serving as one bit of memory...
becomes
metastableMetastability in electronics is the ability of an unstable equilibrium electronic state to persist for an indefinite period in a digital system. Note this definition does not guarantee all of the properties that are sometimes demanded for a metastable state in statistical mechanics...
.
Example
Some
oscilloscopeAn oscilloscope is a type of electronic test instrument that allows signal voltages to be viewed, usually as a two-dimensional graph of one or more electrical potential differences plotted as a function of time or of some other voltage...
s provide a method for triggering on runt pulses. The oscilloscope triggers when the signal crosses one of two voltage
threshold-Film and television:* Threshold , an adaptation of the 1958 science fiction film It! The Terror from Beyond Space* Threshold , an American science fiction drama series* "Threshold" , an episode of the TV series...
s, but not both.