page_title: Attenuator (electronics)
section_title: Attenuator circuits
hierarchical_section_title: Attenuator (electronics) / Attenuator circuits
caption_attribution_description: T type balanced attenuator circuit
context_page_description: An attenuator is an electronic device that reduces the power of a signal without appreciably distorting its waveform.
  An attenuator is effectively the opposite of an amplifier, though the two work by different methods. While an amplifier provides gain, an attenuator provides loss, or gain less than 1.
context_section_description: Basic circuits used in attenuators are pi pads (π-type) and T pads. These may be required to be balanced or unbalanced networks depending on whether the line geometry with which they are to be used is balanced or unbalanced. For instance, attenuators used with coaxial lines would be the unbalanced form while attenuators for use with twisted pair are required to be the balanced form.
  Four fundamental attenuator circuit diagrams are given in the figures on the left. Since an attenuator circuit consists solely of passive resistor elements, it is both linear and reciprocal. If the circuit is also made symmetrical (this is usually the case since it is usually required that the input and output impedance Z₁ and Z₂ are equal), then the input and output ports are not distinguished, but by convention the left and right sides of the circuits are referred to as input and output, respectively.
  Various tables and calculators are available that provide a means of determining the appropriate resistor values for achieving particular loss values. One of the earliest was published by the NAB in 1960 for losses ranging from 1/2 to 40 dB, for use in 600 ohm circuits.
caption: T-type balanced attenuator circuit
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