Glossary - alphabet order - "P"


Abbreviation for Positive Emitter Coupled Logic. This is an I/O level in LSI ICs.

LV-PECL output definition ECL output definition Output voltage level cpmparison


Abbreviation for Phase Locked Loop. This is a circuit or IC that can create any output frequency based on a clock signal having a specified frequency. Recently, these are used with variable reception frequency circuits in TV and radios. Seiko Epson has developed and marketed programmable oscillators that include PLLs.

Block diagram of PLL circuit

Reference: SG-8000 Series , PLL Oscillator

PLL oscillator

This is a crystal oscillator that includes a PLL circuit. It can also output at over 100 MHz, which is difficult with an ordinary overtone crystal oscillator.

Reference: PLL , Programmable crystal oscillator

PROM writer

The PROM writer is a programming tool used for programmable crystal oscillators. It is called a PROM writer because it writes frequency data to the internal PROM of programmable crystal oscillators. This is a tool only prepared for use with SG-8000 series. PROM Writer is Seiko Epson's registered name.

Reference: SG-Writer , Programmable crystal oscillator


A package is a container, such as for a crystal chip, or for crystal chip and IC chip. The package's functions include facilitating board mounting of devices and maintaining an internal vacuum or inert gas in order to optimize the internal crystal's oscillation characteristics.

Pb free product

Pb free products are products that all lead has been eliminated from its components and surface-treatment materials. However, Pb free products require a higher soldering temperature than Pb soldered products when mounted.

Reference: Working for EU RoHS/Pb FREE , Reflow profile

Reflow profile of Pb free products

Period jitter

A type of jitter defined in specification. See "jitter".

Reference: Jitter

Phase noise

This refers to useless energy that is radiated near the oscillation frequency, and that occurs due to the internal and external environmental factors (noise) of a crystal oscillation circuit. Wireless signal transmission errors can occur when this noise value is too high.

Photolithography processing

This type of processing uses chemicals to dissolve a crystal plate or metal layer, usually in order to make a tuning fork crystal shape for a tuning fork crystal chip, or to create electrodes. Before this processing approach was developed, mechanical processing was used, but photolithography processing offers the following advantages.

  1. This is the same process as is used to fabricate ICs with high dimensional accuracy, so crystal chips can be made very small and very precise, etc.
  2. Chemical processing enables several hundred tuning fork crystal chips to be made from a single crystal plate, with consistent quality and at low cost.
  3. Since no strain remains in a crystal chip, the resulting crystal chip provides a stable oscillation frequency for a long time.

Reference: mechanical processing

Piezo-electric effect

The piezo-electric effect is the electric charge that is generated in a particular axial direction when pressure is applied in a particular crystal axial direction against a typical crystalline material (such as quartz crystal). By contrast, the mechanical stress that occurs when a charge is applied in the same axial direction is called a reverse piezo-electric effect. Materials that have these properties include monocrystalline materials such as quartz crystal (SiO2), lithium tantalum trioxide (LiTaO3), and lithium niobium trioxide (LiNbO3), as well as polycrystalline (piezo-ceramic) materials such as barium titanium trioxide (BaTiO3). Each of these materials has its advantages and disadvantages, and quartz crystal is best for stable oscillation.

Piezo-electric effect Reverse piezo-electric effect

Reference: Piezo-electric element

Piezo-electric element

This refers to any crystal element that has a piezo-electric effect. These crystal elements include monocrystalline elements such as quartz crystal (SiO2), lithium tantalum trioxide (LiTaO3), and lithium niobium trioxide (LiNbO3) elements, as well as polycrystalline ceramic elements.

Reference: Piezo-electric effect


This refers to the polishing of crystal plate surfaces. This includes both lapping (with a fine-grained abrasive) and polishing (with a polishing cloth dipped in a polishing substance). These types of surface processing are important for obtaining the desired frequency and to improve the vibration efficiency. In particular, surface accuracy has a very large effect on the characteristics of AT crystal units. Finer surface accuracy is required for higher frequencies.

Programmable crystal oscillator

This indicates the crystal oscillators that include a PLL circuit and can be programmed to output a desired frequency. Being able to program for any output frequency facilitates short-lead-time, small-lot production. A special programming tool is necessary to write frequency data to blank crystal oscillators. Epson's programmable crystal oscillators are the SG-8xxx Series, and are programmed by the SG-Writer programming tool.

Reference: Product lineup , SG-Writer

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