1 Most common high frequency chip: Chip Attenuator

1.1 Functions and usage of various attenuators

Various attenuators

・There are many kinds of attenuators
・Chip attenuators are integrated into coaxial or module type attenuators.

Chip attenuators

The function of an attenuator

Attenuators weaken (attenuate) the electrical signals to the desired level. The amount of attenuation is expressed in decibel (dB). Attenuation is typically negative value but usually omit minus ”-” when it is expressed.

Example of attenuation

Example of attenuation

How attenuators are used

Attenuators can weaken (attenuate) the electrical signals to desired level. Here are some examples:

1)Level adjusting attenuator

Level adjusting attenuator

2)Impedance matching (as a safety device) 



Used in measurement taking advantage of wide band and linearity.

1.2 Attenuator circuit and integration into 1 chip

Attenuator circuit

Attenuators can be constructed using discrete resistors forming T, π, or double π shapes. In communication, the impedance must match 50Ω.

Attenuator circuit

Examples of resistance combination for specific attenuation values

According to the attenuation value and the type of the circuit, the combination of resistance varies significantly. The table right shows the examples of π circuit resistance combination. These combinations also give 50Ω impedance matching.

Examples of resistance combination for specific attenuation values

ATT(dB) R1,R3(Ω) R2(Ω)
1 869.5 5.8
2 436.2 11.6
3 292.4 17.6
4 221 23.8
5 178.5 30.4
6 150.5 37.4
7 130.7 44.8
8 116.1 52.8
9 105 61.6
10 96.2 71.2

Chip attenuator is an integration of 3 resistors

If you use discrete resistors to form an attenuator, you need 3 resistors.
One chip attenuatorcan function as 3 discrete resistors and has the following advantages


・Guaranteed performance with one component
・Signal and ground terminals in one component simplify the PC board layout.
・Minimize parasitic capacitance and inductance


Please feel free to contact us about products,
requesting documents and samples.