Tech Info - Crystals
Tech Info - Oscillators
Tech Info - Filters

Aging: A change in the frequency and/or the resistance of a quartz crystal unit with the passage of time.

CMOS: The abbreviation for "Complementary Metal Oxide Semiconductor."

Control Voltage The range of voltage used to pull the frequency.

Cycle: One complete repetition of an event.

Deviation: The amount by which a quantity differs from its nominal value. For our purposes, the amount by which a frequency differs from the nominal or specified frequency.

Dew Point: The temperature at which a condensable component of a gas starts to condense into a liquid.

ECL: The abbreviation for "Emitter Coupled Logic."

Enable/Disable Function: A control function that enables or disables the output of the oscillator. When the oscillator is in its disabled state, the oscillator is still running internally, but no output is coming from the output pin.

Enable/Disable Time: The time between application of the proper voltage to the enable/disable pin and the moment the output becomes enabled or disabled.

Extended Temperature Range: An option available on selected oscillators. Extended temperature range is -40C to +85C.

Fall Time: The amount of time it takes the output voltage to go from Logic 1 to logic 0.

Frequency: The periodic repetition of an event within a unit of time. In an electrical circuit, the number of waves that pass a given point in one second. The number of times a resonator plate oscillates or vibrates in one second. The nominal or desired frequency specified by a customer.

Hertz: The basic unit of measurement of frequency, "Hertz" replaces the term "cycle per second". Used to denote one complete occurrence of an event in one second.

Hz: The abbreviation of the word "Hertz."

Holder: The complete housing for a quartz resonator plate. The holder includes the base and cover.

Impedance: The total opposition presented by a circuit or device to the flow of alternating current. Impedance is measured in "ohms" and is represented by the letter "Z."

Input Current: The amount of current consumed by the oscillator.

Insulator: Any of several materials that do not easily permit the passage of electricity.

ISO: The abbreviation for "International Organization for Standardization."

Kilo: A prefix, abbreviated "k," used to denote units of thousands. One "Kilo" is one thousand. In our industry, a frequency of one kilohertz is a frequency of one thousand hertz (cycles per second).

kHz: The abbreviation for "kiloHertz," used to describe the frequency of a crystal or oscillator in terms of thousands of Hertz (cycles per second). A frequency specified as "10.0 kHz" would be understood as being a frequency of 10,000 Hertz (cycles per second). A frequency specified as "10,000 kHz" would be understood as being a frequency of 10,000,000 Hertz (cycles per second).

Linearity: The uniformity of the shift in frequency over voltage change, when pulling the frequency of a VCXO.

Load Impedance: The impedance presented by a load connected to a generator or other source.

Mega: A prefix, abbreviated "M," used to denote units of millions, 106. One "Mega" is equal to one million. In our industry, one Megahertz is a frequency of one million hertz (cycles per second).

milli: A prefix, abbreviated "m," used to denote units of thousandths, 10-3. One "milli" is equal to 1/1000th of a unit.

OEM: The abbreviation for "Original Equipment Manufacturer."

Oscillator: A circuit or device that produces an alternating current of a specific frequency at its output terminals.

Output Current: Is represented by IOL and IOH, which is the output current at VOL and VOH.

Output Load (Fan out): The capacity of the oscillator to drive other devices. TTL devices are specified in the number of gates that can be driven; i.e., 10 TTL gates. CMOS outputs are specified in picoFarads (pF); i.e., 15pF or 50pF loads.

Output Voltage: Is represented by VOL, which is the maximum voltage that output low will be and VOH which is the minimum voltage that output high will be.

Overlap Time: The time, measured at 50% Vp-p, at which the two outputs of a complementary output ECL oscillator overlap.

pF: The abbreviation for "picoFarad," used to describe a fractional part 10-12 (one trillionth) of one Farad.

Pico: A prefix used to describe a sub-multiple of a number. One pico is one trillionth 10-12 of a unit.

Pin Through: Refers to a package with leads. When the device is mounted on a PCB, the leads go through the board.

PPM: The abbreviation for "Parts Per Million," a method of calculation used to specify the permissible frequency deviation of a crystal or oscillator. May also be seen as "ppm." Both are correct.

Pullability: The amount the frequency can be made to deviate by varying the voltage on the control pin.

Resistor: A component used to introduce resistance into a circuit.

Rise Time The amount of time it takes the output voltage to go from Logic 0 to logic 1.

Second: The basic unit of measure of time, equivalent to "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom." For our purposes, one "second" is 1/60th of a minute.

Sine wave: A periodic wave that can be represented by a sine curve. The amplitude of such a wave is a function of the sine of a linear quantity such as phase or time.

SMD: The abbreviation for "Surface Mount Device."

Square Wave: An alternating or pulsating current or voltage whose wave shape is square.

Stability: The maximum amount of frequency deviation of the oscillator. Stability includes the tolerance at 25 C; drift over operating temperature range; changes in input voltage; changes in load, shock, vibration; and aging.

Standby Current: Amount of current consumed by the oscillator when it is in its standby mode.

Standby Function: A control function similar to the Enable/Disable function. In this case, the oscillator actually stops oscillating. This type of oscillator draws less current than an Enable/Disable type oscillator (when both are in their disabled states).

Start-up Time: The period from the instant voltage is applied to the oscillator until the oscillator output is stabilized.

Supply Voltage: Voltage required for the oscillator to operate within specification.

Surface Mount: Refers to a package with pads that mount to the surface of the PCB.

Symmetry: A measure of the uniformity of the output waveform.

T.C.X.O: The abbreviation for "Temperature Compensated Crystal Oscillator." Such an oscillator contains a temperature sensing network that adjusts the output frequency, thereby allowing the frequency to remain constant over a specified temperature range.

Tri-state: The ability to turn the output on or off using pin one for control. The output will go to a high impedance when disabled, which facilitates the use of Auto Test Equipment (ATE). Note: Tri-state may be substituted for non-tri-state if pin #1 is left open or held high.

TTL: The abbreviation for "Transistor-Transistor Logic."

V.C.X.O: The abbreviation for "Voltage Controlled Crystal Oscillator." Such an oscillator contains a network that employs changes in voltage to change the output frequency.

Volt: The basic practical unit of difference of (electrical) potential.


home | company | products | support | news | contact | site map
Copyright 2004-2005 King Fai International, Inc. All Rights Reserved.