Analogue switch

An electronic switch, and analog switch or a semiconductor switch, is an electronic device which realizes the function of a switch in the form of a semiconductor device. Above all, field-effect transistors ( FET) and bipolar transistors and diodes are used - in this context one also speaks of switching transistor or switching diode - but also thyristors are used as electronic switches.

In principle, also SSR and PhotoMOS relays electronic switches, but they are usually not referred to as such.

In the switched state electronic switches as well as other switches should connect the input as quickly as possible and with low impedance output, however, both isolated from each other as well as possible in the off state. This is possible only in a limited by the operating voltage range and limited potential separation from the control input for analog switches in the rule.

Analog technology

Analog switches operate much faster than mechanical relay or switch contacts and work bounce-free and wear-free. However, they have over those a higher contact resistance in the ON state and a lower insulation capacity in the off state.

Analog switches are used to sample and hold circuits at the interface of analogue to digital technology, the switching signal to the switching matrices and in time-division multiplexed data acquisition.

The properties of an electronic analog switch are mainly characterized by the following values ​​:

  • Resistance ( typically ≤ 100 Ω )
  • Reverse resistance (typically ≥ 1 M )
  • Analog voltage range in which the input voltage is transmitted without distortion.
  • Switching time ( usually ≤ 1 microseconds )
  • Type of digital control (usually a TTL - and CMOS - compatible signal )

Furthermore, the following values ​​are specified for analog switches:

  • Electrical capacity of the switching path to the rest of the circuit
  • Charge that is exchanged during the switching operation due to the control; it leads to a Störspannungsimpuls on the signal line

In practice, the analog switches are often driven by TTL control signals. If the analog voltages to be switched out of the range 0 V to 5 V to be possess analog switch IC Betriebsspanungsanschlüsse permitting higher positive and negative values.

And mechanical switch, digital electronic switch includes: the Hall key thereto requires an operating voltage, and uses a permanent magnet as an operating element, whereas piezo switches do not need operating voltage; to produce the control voltage to a piezo-ceramic actuator.

Digital technology

In digital technology, gates are used to link digital signals to each other, instead of analog switches.

A special form of the electronic switch is a duplexer, the radar technology, which can connect very quickly and without moving the antenna elements with either the transmitter or the receiver.

  • Switch
  • An electronic circuit
JFET Analogue electronics
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