Glossary Terms and Definitions Beginning with the Letter  t

The small size of the TEC allows precision thermal control of individual components such as fiber optic laser drivers, precision voltage references, or any other temperature critical device. Temperature-critical components are integrated with a TEC and a temperature monitor into a single thermally-engineered module.

A "thermoelectric controller" (also abbreviated TEC) is an electronic circuit that controls the current that drives the junction. These can be quite sophisticated. Many can drive a positive or negative current (so they can heat or cool), use PWM for efficiency, and incorporate control to regulate the amount of current. Examples of such circuits are linked below.

See: App Note 3318, HFAN-08.2.0: Thermoelectric Cooler (TEC) Control.

See: Video Basics

See: Maxim/Dallas's full line of thermal management integrated circuits.

As an example, if a 12kHz signal is applied to the input, THD would look at energy on the output occurring at 24kHz, 36kHz, 48kHz, etc. and compare it to the energy occurring at 12kHz.

Common misspellings: Transciever, Tranceiver, Transeiver, Transiever, Tranciever, Transcever.

Examples:

• Interface devices (such as line drivers and receivers, RS-232, RS-485, RS-422, CAN, LVDS, or USB)
• Wired communications ICs, such as T1/E1/J1 Transceivers (LIU and Framer) and T3/E3 Transceivers
• Wireless communications such as IF and RF transceivers

The term derives from "transfer conductance" and is measured in siemens (S), where 1 siemens = 1 ampere per volt. It was formerly measured as "mho" (ohm spelled backwards).

The term derives from "transfer conductance" and is measured in siemens (S), where 1 siemens = 1 ampere per volt. It is represented with the symbol g_m. The basic gain of vacuum tubes and FETs is expressed as transconductance.

See: Transconductance Amplifier Buffers Current Transformer

The number of data transfers is less than the number of bits transmitted when encoded data has more bits than the raw data. As an example, a PCIe serial bus uses 10 bits to encode eight data bits. (Extra bit space may be used to encode a clock, error-detection redundancy, etc.)

Data rates are commonly expressed in transfers per second, gigatransfers per second (GT/s) and megatransfers per second (MT/s).

A transformer consists of two magnetically coupled coils. Alternating current in one (called the "primary") creates a changing magnetic field which induces a current in the second coil (the "secondary"). A core made of iron or ferrite generally connects the two coils, but higher frequency devices can work without a ferrous core.

Transformers have two primary functions: Voltage transformation and isolation:

• The voltage of the secondary can be higher or lower than the voltage that drives the primary and is determined by the ratio of turns of wire in the two coils.
• Isolation refers to the fact that the coils are connected only by a magnetic field, so they can be independent of a common ground.

Primary applications are for power and for signal isolation / impedance transformation.

An autotransformer is a transformer with a single coil with intermediate "taps" to effect the changed outgoing voltages. They do not provide isolation.

Transformer capacity is rated in kilovolt-amps (KVA): The volts x amps / 1000.

The unit for transresistance is the ohm.

See: Transconductance Amplifier Buffers Current Transformer

Usually built from silicon but can be constructed from other semiconductor materials. There are two major types: The FET (field-effect transistor) and the bipolar junction transistor (BJT).

The first transistor was invented in 1947 at Bell Labs by Michael John Bardeen, Walter Brattain and William Shockley.

Examples:

• A radio transmitter that modulates the signal on a carrier and transmits it over the airwaves
• An ultrasonic transducer that sends the signal over ultrasound frequencies
• A line driver that drives a backplane
• A circuit that drives an interface (e.g., USB, serial, LVDS)
• A fiber optic device that emits light pulses

Commonly used for a bus, in which any several devices can be selected. If the bus has a pull-down resistor, the tri-state arrangement achieves an OR function, dubbed "wired-OR."

Tri-State is a trademark of National Semiconductor.