3. Main characteristics of chip attenuators and PAT series

3.1 Chip attenuator performance characteristics

Attenuation and VSWR

For attenuators, attenuation and voltage standing wave ratio (VSWR) are the two most important performance characteristics

Attenuation and VSWR

PAT series performance specification

In PAT series, attenuation is offered in 1dB increment. VSWR depends on the frequency and chip size.

PAT series performance specification

PAT series performance data

In the PAT series, the amount of attenuation can be selected in 1 dB steps, and the product names differ. (Refer to the catalog for details). Also, the tolerance is specified for each attenuation, and the actual characteristics are within this specification.The figure below shows PAT1220-C-3dB (3dB product) attenuation and VSWR characteristic data.

PAT series performance data

PAT series performance data02

3.2 S parameter, important characteristics in high frequency electronics

What is S parameter?

S-parameters are parameters often used in high-frequency circuits, and indicate the relationship between incident waves, transmitted waves, and reflected waves. In a two-port device, it is represented by four parameters, and the relationship is as shown below.


S parameter is measured with Network analyzer

S-parameters can be measured with a network analyzer.When the measurement target (DUT) is an attenuator S11, S21, S12, S22 are as follows

Network analyzer


S parameter


DUT: attenuator

S11: Return Loss
S21: Attenuation
S12: Attenuation
S22: Return Loss  

Return loss is expressed with VSWR as follows
Return Loss=
20log10(VSWR+1/VSWR-1) (dB) 


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