Exact Design and Analysis of Double- and Triple-Tuned Band-Pass Amplifiers

The purpose of this paper is to present a quick, complete, and exact method of design and analysis of double- and triple-tuned band-pass amplifiers. The necessary small-percentage pass-band equations are derived giving the relationship between the circuit characteristics and the response characteristics. These circuit characteristics are: the resonant frequency f0, coefficient of coupling K, the circuit Q, and the input and output capacitances Cin, and Cout. The response characteristics are: the percentage bandwidth between peaks Δfp/f0, the peak-to-valley response ratio within the pass band VpI/Vv, the peak-to-"skirt" response ratio Vp/V at different skirt-to-peak bandwidth ratio points Δf/Δfpoutside the pass band, the circuit gain at the peaks, and the phase shift θ at any frequency. These design equations, extended to the case of one to eight cascaded stages, are incorporated in two sets of conveniently used nomographs, one for double-tuned circuits and one for triple-tuned circuits. Specific examples of the use of these nomographs are given.