High‐performance balanced dual‐band bandpass filter with controllable bandwidth and frequency ratio

In this study, a novel high‐performance balanced dual‐band bandpass filter (BPF) with controllable bandwidth and frequency ratio is proposed. The symmetrical dual‐band bandpass characteristics on both sides of the center frequency f0 can be achieved by cascading two one‐wavelength edge‐coupled ring resonators through coupling. To suppress the common‐mode (CM) noises, a high‐performance balanced dual‐band BPF is designed and analyzed. The elements affecting the controllable filtering bandwidth and frequency ratio are discussed. For practical verification, a microstrip prototype for GPS applications is manufactured and measured with great out‐of‐band rejection and excellent CM suppression.