High frequency band-pass filter

Claim 1

In a high frequency band-pass filter circuit, means forming an input resonator circuit loop tuned for a resonant frequency within the passband of the filter and having a first inductor and a first capacitor, means forming an output resonator circuit loop tuned for a resonant frequency within the passband of the filter circuit and having a second inductor and a second capacitor, means forming a third capacitor common to both of said input and output resonant circuit loops for decoupling same, means forming fourth and fifth capacitors for coupling into and out of said input and output resonators, respectively, the improvement wherein, all of said five capacitors are formed by a stack of first, second, third, fourth and fifth conductive structures insulatively stacked with respect to each other and with respect to a sixth ground plane structure, said five structures insulatively stacked with respect to each other and with respect to a sixth ground plane structure, said five structures being stacked with said first structure insulatively disposed immediately overlaying said sixth ground plane structure to define said third capacitor therebetween, said second and third conductive structures each of smaller capacitive area than said first structure being disposed insulatively immediately overlaying said first structure to define said first and second capacitors, respectively, and said fourth and fifth structures each of smaller capacitive area than said second and third structures being insulatively disposed immediately overlaying said second and third structures, respectively, to define said fourth and fifth capacitors, respectively.