Miniaturized and Wideband on-Chip Bandpass Filter with Multiple Transmission Zeros Based on Mixed-Coupled T-type Unit

In this letter, a miniaturized wideband bandpass filter with wide stopband based on Mixed-Coupled T-type Unit (MTU) is proposed. The proposed lumped BPF which is evolved from the distributed prototype gets further miniaturized. What is more, two transmission zeros near the passband caused by two parallel MTUs and grounded capacitors can improve the frequency selectivity. The stopband gets extended for two transmission zeros away from the passband which are caused by two opening MTUs. The proposed filter is modeled and simulated using integrated passive device technology. The center frequency f
0
of the proposed filter is 3.5 GHz and 3-dB FBW is 47%. What’s more, the wide stopband up to 3.94 f
0
with a 20-dB rejection level is achieved. Its size is only 1.02 mm*1.34 mm that is 0.012*0.032 $\lambda _0^2$ (λ
0
is the free-space wavelength at f
0
).