attenuator

    Attenuator is within a specified range of frequencies, a kind of used to introduce a scheduled attenuation circuit. General with the introduction of attenuation decibels and its characteristic impedance ohms to indicate. Widely used in cable TV system attenuator in order to meet the requirements of multiple ports for level. Such as input and output level of amplifier, branch of attenuation control. Attenuator for source attenuator and active attenuator. Active attenuator to match the other heat sensitive components of variable attenuator, device or slope for automatic gain control circuit within the amplifier. Passive attenuator has fixed attenuator and adjustable attenuator. Fixed attenuator is composed of resistance, will not affect the frequency characteristics of common type T or PI network; Adjustable attenuator is composed of potentiometer and level adjustment of use in debugging. Request attenuator of input and output impedance matching with interface end, cable television system for euro 75. Frequency characteristic of the attenuator to satisfy the requirement of the system frequency range, the frequency range of attenuator attenuation has nothing to do with the frequency. Therefore, common resistance element. Different frequency range, attenuator are different form. Useful coaxial attenuator; Commonly used in the waveguide system, absorb the diaphragm of electric field energy attenuator; Also have used solid-state diode (such as PIN diodes) at microwave frequencies within waveguides or coaxial line can be electrically tuned attenuator of the system. Attenuator is often used in a variety of telecommunications equipment and electronic instruments.
Attenuator often consists of a resistor, such networks with no reactive element, therefore only amplitude attenuation without phase shift can be normal work over a very wide frequency range. Attenuator used in amplifier input end and output end, adjust and control the amplifier's input, output level, can also improve the impedance characteristics. Attenuator is commonly used in the branch unit, various branches attenuation.
Attenuator technical parameters are as follows:
(1) the attenuation of alpha. The input and the output level is poor, can use voltage attenuation or power attenuation, said expressed in the ratio of the input voltage and output voltage is relatively simple. Alpha = U1 / U2 (value) of alpha = 20 lgu1 / U2 (dB) (dB) of U1 - input voltage; U2 - the output voltage. There are 3, 6, 9, 12, 15, 20 db fixed attenuator attenuation of the variety of models. And attenuation adjustable adjustable attenuator, besides theoretical attenuation, adjustable attenuator and additional insertion loss about 0.5 dB (a), so in the system design, need will increase some attenuation calculation.
(2) the in-band flatness. Said within the working frequency attenuation of inconsistencies, such as in-band flatness + / - 0.5 dB. For adjustable attenuator V band of plus or minus 1 dB, U band of plus or minus 1.5 dB.
(3) the current carrying capacity. Some attenuator cannot by power supply current, some attenuator can by power supply current, such as by 3 a current.