Glossary - alphabet order - "T"


Abbreviation for "Temperature Compensated X'tal (crystal) Oscillator". For further description, see "temperature compensated crystal oscillator".

Reference: Temperature compensated crystal oscillator


Abbreviation for Transistor Transistor Logic. This type of logic is used in digital logic ICs that consist mainly of transistors. Although this type of IC has been the principal type since the advent of semiconductors, CMOS ICs are now becoming the principal type. However, TTL ICs are still the solid leader at the I/O level.

TTL load

This is a load circuit which is connected to output and has a TTL structure. The high/low threshold value is 1.4 V.

TTL load timing chart Test circuit

Temperature compensated crystal oscillator

This crystal oscillator, called TXCO for short, includes a function for compensating the frequency variation according to the crystal oscillator's temperature. Generally, AT crystal devices have relatively better temperature characteristics. In order to obtain more stable frequencies, the temperature variation is compensated based on signals sent from a temperature sensor. There are two frequency compensation methods: an analog compensation method and a digital compensation method. Epson markets the TG Series of temperature compensated crystal oscillators.

Reference: TCXO

Temperature sensing crystal

This refers to a crystal device used for measuring temperature. It exploits typical characteristics of a crystal device, where oscillation frequency changes according to the temperature change.

Thickness shear vibration

This is a vibration mode in crystal units. As shown in the drawings at right, in this vibration mode the top and bottom surfaces along the crystal plate's thickness direction move opposite to each other. This mode is used in high-frequency crystal units such as AT crystal units. The frequency f is a function of the crystal chip's thickness T. For the fundamental frequency, f = k/T (k: constant)

Fundamental mode Third-order overtone mode

Reference: AT crystal unit

Through-hole package

This is a package that is mounted by insertion of pins into holes made in a circuit board. Such packages include DIP packages and SIP packages.

Reference: DIP package , SIP package , SMD package


Amount of P-type polarized light on the transmission path after transmitting through an optical component.

Transmission wave front aberration (Wavefront aberration for transmission)

Wavefront aberration in a transmission path.


Amount of S-type polarized light on the transmission path after transmitting through an optical component.

Tuning fork crystal unit

This type of crystal unit uses a tuning fork-shaped crystal chip. Its advantages including being suited for relatively low frequencies and being compact with a vibration plate that can be separated from its supports. See "flexure vibration" for description of the vibration mode.

Tuning fork crystal chip aStructure of tuning fork srystal unit

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