These calculators will provide schematics and ideal component values for a variety of filter types (e.g. Butterworth, Chebyshev/Tchebysheff, Bessel) and attenuator configurations. Some will also provide response curves. To implement the desired design with standard components, it may be necessary to use multiple component values in series or parallel configurations to approximate the calculated values. For example, the design for a 6 dB 50 Ω attenuator calls for a 37.4 Ω resistor, a value that is not commonly available. The attenuator can instead be built with two 75 Ω resistors in parallel, producing a very good 6 dB attenuator from standard components:  |  | | "Ideal" 6 dB Attenuator Design | Actual 6 dB Attenuator Implementation |
A more complete Attenuator Application Note describes these techniques in more detail, including examples of many commonly-required attenuation ratios, measured performance, and oscilloscope captures. |