- Analogue switch
The analogue (or analog) switch, also called the bilateral switch, is an electronic component that behaves in a similar way to a
relay, but has no moving parts. The switching element is normally a MOSFET, which is a type of transistor. The control input to the switch is a standard CMOSor TTL logic input, which is shifted by internal circuitry to a suitable voltagefor switching the MOSFET. The result is that a logic 0 on the control input causes the MOSFET to have a high resistance, so that the switch is off, and a logic 1 on the input causes the MOSFET to have a low resistance, so that the switch is on. Analogue switches are usually manufactured as integrated circuits in packages containing multiple switches (typically two, four or eight). These include the 4016 and 4066 from the 4000 series.
Unlike a relay, however, the analogue switch does not provide electrical isolation between the analogue signal and the control signal. This means that it should not be used in high-voltage circuits where such isolation is desired. Also, since there is only a low current path between the input and output, the maximum current allowed through the switch may be smaller than that in a typical relay. There are also some constraints on the polarity and range of voltages of the signal being switched.
Important parameters of an analogue switch are:
*on-resistance: the resistance of the MOSFET when switched on. This commonly ranges from 5 ohms to a few hundred ohms.
*off-resistance: the resistance of the MOSFET when switched off. This is typically a number of megohms or gigaohms.
*signal range: the minimum and maximum voltages allowed for the signal to be passed through. If these are exceeded, the switch may be destroyed by excessive currents. Older types of switches can even "latch up", which means that they continue to conduct excessive currents even after the faulty signal is removed.
*charge injection. This effect causes the switch to inject a small
electric chargeinto the signal when it switches on, causing a small spikeor glitch. The charge injection is specified in coulombs.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Switch — For other uses, see Switch (disambiguation). Electrical switches. Top, left to right: circuit breaker, mercury switch, wafer switch, DIP switch, surface mount switch, reed switch. Bottom, left to right: wall switch (U.S. style), miniature toggle… … Wikipedia
Analogue television in the United Kingdom — includes terrestrial, satellite and cable services broadcasting using analogue television signals.Analogue terrestrial television in the United KingdomAnalogue terrestrial television in the United Kingdom is, traditionally, the method most people … Wikipedia
Analogue terrestrial television in the United Kingdom — is, traditionally, the method most people in the UK, Channel Islands and the Isle of Man used to receive television. Analogue terrestrial television is currently being phased out in the UK and will be completely replaced by digital terrestrial… … Wikipedia
analogue — UK US (US USUALLY analog) /ˈænəlɒg/ adjective ► IT, COMMUNICATIONS using a system in which information, such as sound or images, is stored or sent in a continuously changing form, such as electrical signals, radio waves, or film: »analogue… … Financial and business terms
Clan Analogue — Founded 1993 Genre Dance Music Country of origin Australia Location Sydney … Wikipedia
Digital television transition — The digital television transition is the process in which analog television broadcasting is converted to and replaced by digital television. This primarily involves both TV stations and over the air viewers; however it also involves content… … Wikipedia
Digital terrestrial television — List of digital television broadcast standards DVB standards (Europe) DVB S (satellite) DVB S2 DVB T (terrestrial) DVB T2 DVB C … Wikipedia
Digital radio in the United Kingdom — A typical DAB digital radio receiver with the Digital Radio Development Bureau DAB digital radio marketing logo In the United Kingdom, the roll out of digital radio is proceeding since test transmissions were started by the BBC in 1990. The UK… … Wikipedia
List of digital television deployments by country — This is a list of digital television deployments by country, which summarises the process and progress of transition from analogue to digital broadcasting. It is current as of December 2007. The transition to digital television is a process that… … Wikipedia
Broadcasting (Amendment) Act 2007 — The Broadcasting (Amendment) Act 2007 is an Act of the Oireachtas (Irish parliament).It deals with Irish Analogue broadcasting systems and the amendment of legislation on Digital Terrestrial Television dating back to 2001. This act amends… … Wikipedia