METHOD AND APPARATUS FOR ADJUSTING THE IMPEDANCE OF A MICROSTRIP TRANSMISSION LINE

摘要

The interdigital capacitor (10) including a plurality of conductive and dielectric finger regions. The conductive finger regions are made of the same material type as a microstrip transmission line (12). The conductive finger regions are comprised of individual conductive fingers (14) and the individual conductive fingers (14) provide a predetermined level of impedance to the microstrip transmission line. The plurality of conductive finger regions are comprised of a first finger region (18) and a second finger region (20). The first finger region (18) is coupled to the microstrip transmission line (12) and the second conductive finger region (20) is coupled to ground (22). The individual conductive fingers (14) of the first conductive region (18) are located parallel and interspersed with the individual conductive fingers (14) of the second conductive finger region (20). Because the individual fingers (14) of the conductive finger region provide a predetermined level of impedance to the interdigital capacitor (10), the value of the interdigital capacitor (10) can be adjusted by a known amount by removing one or more individual conductive fingers (18). This in turn provides a known response in the phase of a signal travelling on the microstrip transmission line (12).