1–1.7-GHz Single-Voltage-Controlled Tunable MMIC BPF With Over 45-dB Rejection to 30 GHz Using Tapped Inductor Technique

This paper presents a novel fourth-order single-voltage-controlled (SVC) tunable monolithic microwave integrated circuit (MMIC) bandpass filter (BPF) for tunable filter bank applications. Utilizing the tapped inductor technique (TIT), the proposed filter achieves compact magnetic coupling with reduced loss, avoiding the use of bulky inductor-or transformer-based coupling structures. The filter demonstrates a continuous tuning range from 1 GHZ to 1.7 GHz with approximately 60% fractional bandwidth (FBW), while maintaining a consistent insertion loss (IL) of 4.55 ± 0.25 dB. A high out-of-band rejection of 45 dB up to 30 GHz [17.6 times center frequency (fcen)] is also achieved. These performances promise significant application potential for tunable filter banks.