Compact balanced filters with enhanced differential-mode out-of-band response using coupled slotline structure

A balanced bandpass filter (BBPF) with high common‐mode rejection (CMR) and extended differential‐mode (DM) stopband is presented. It is based on miniaturized Pi‐network ring resonators with loaded inductors. This structure permits the design of the common‐mode (CM) and DM resonances independently, which gives plenty of flexibility when designing the filter. Stubs are added along the symmetry plane to improve the CMR. A microstrip BBPF is designed at 921.7 MHz with a fractional bandwidth of 8.4% and a DM stopband of 10.13 f 0 ${{\boldsymbol{f}}}_{{\bf{0}}}$ for S21 < −30 dB. The CMR is better than −20 dB up to 10 f 0 ${{\boldsymbol{f}}}_{{\bf{0}}}$.

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“…In ref. [12], the CMR and the DM suppression are of 13

{f}_{0}^{{DM}}

; however, its double‐sided implementation increases fabrication complexity. The work in ref.…”

Section: Introductionmentioning

confidence: 99%

Balanced bandpass microstrip filter with high common‐mode rejection and extended stopband

Romero‐Ramirez

Olvera‐Cervantes

Kataria

et al. 2023

Micro & Optical Tech Letters

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“…Here the spurious frequency position can be controlled through the resonators impedance and length ratios of the connected transmission lines [4,5]. The inclusion of transmission zeros where the spurious frequency occurs is another common method for stopband extension [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Compact closed‐loop resonator filters with wide spurious free band and extended common‐mode noise suppression

Arbelaez¹,

Olvera

Corona

et al. 2020

IET Microwaves, Antennas & Propagation

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A theoretical analysis is presented for miniaturised filters with an extended stopband and extended common‐mode (CM) rejection, using loaded closed‐loop resonators. A numerical method is presented to solve the equations extracted from the ideal transmission line model. Selection of critical resonator parameters to minimise filter area while simultaneously maximising the differential‐mode (DM) stopband or the CM noise suppression is explored. The trade‐off between size, stopband and CM rejection is presented and used to design three filters at 1 GHz, which are designed to verify the proposed concept. First, a differential second‐order filter with an extended DM stopband (S21d<−20 dB) up to 6.8fc and extended CM noise suppression (S21c<−20 dB) up to 6.42fc is realised to show the parameter trade‐offs. Then optimal resonators are used to develop a compact singled‐ended filter (0.011λg2) with an extended stopband (S21<−30 dB) up to 8.2fnormalc and the smallest size. Lastly, a second order filter with an optimal extended CM rejection (S21c<−20 dB) up to 6.64fnormalc is presented. Measured results are presented. All three filters stand out compared to other works by exhibiting the smallest footprint relative to the operating frequency.

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Compact balanced filters with enhanced differential-mode out-of-band response using coupled slotline structure

Cited by 2 publications

References 6 publications

Balanced bandpass microstrip filter with high common‐mode rejection and extended stopband

Balanced bandpass microstrip filter with high common‐mode rejection and extended stopband

Compact closed‐loop resonator filters with wide spurious free band and extended common‐mode noise suppression

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