Microstrip Realization of Trisection Synthesis With Frequency-Dependent Admittance Inverter

Abstract

Abstract-Frequency-dependent admittance (J-) inverter is incorporated in synthesis of microstrip trisection filters to achieve a quasielliptic function response. In the admittance matrix of the lowpass prototype, certain coupling is modeled by a constant J-inverter multiplied by the complex frequency variable s. Direct synthesis of three lowpass prototypes is presented. Based on the standard lowpass to bandpass transformation, coupled microstrip resonators with both electric and magnetic coupling are devised to implement the J-inverter with desired frequency-dependent characteristics. Tapped-line input/output is used and several transmission zeros can be created in the upper and lower rejection bands. In experiments, a third-order filter with four zeros, a fourth-order circuit with three zeros, and a fourth-order filter with five zeros are designed and fabricated. Measured results are compared with the simulation responses to validate the theory.

Microstrip cascaded trisection filter with multiple pairs of transmission zeros

“…The comparison of polynomials used in [7] to determine element values is only suitable for the circuit with a single pair of zeros. For the synthesis of a CT filter with multiple zero pairs, the lowpass prototype of a single trisection shown in Fig.…”

“…In [6], trisection filter with a resonant form of cross-coupling is proposed to produce a pair of zeros. In our previous work [7], it is found that this resonant coupling can be modeled by a frequency-dependent admittance J-inverter, i.e. a J-inverter multiplied by the complex frequency variable s. Element values of the lowpass prototype with N = 3 and 4 can be easily extracted by the comparison of the polynomials in ABCD matrices with the general Chebyshev transfer function.…”

A New Diode-Clamped Multilevel Inverter for Capacitor Voltage Balancing

“…Compared with conventional two-level converters, multilevel converters show great advantages such as: high power quality of waveforms, low switching losses, high-voltage capability and low electromagnetic interference (EMI) [3][4][5][6][7][8][9]. In general, multilevel converters can be divided into three types: diode-clamped multilevel converters, flying capacitor multilevel converters and cascaded multilevel converters with separated DC sources [10][11][12][13].…”

Design of Even-Order Symmetric Bandpass Filter With Chebyshev Response

“…A design method for a novel directcoupled balanced BPF based on coupled-resonator theory by utilizing λ/4 resonators and λ/2 resonators has been proposed in [11], and two transmission zeros were obtained from the delicate coupled structure. The Chebyshev polynomial is often used as a synthesis method of the filter design [12,13]. A substrate integrated waveguide diplexer with Chebyshev response is presented in [12], and the Chebyshev lowpass prototype is used in its synthesis method.…”

“…The Chebyshev polynomial is often used as a synthesis method of the filter design [12,13]. A substrate integrated waveguide diplexer with Chebyshev response is presented in [12], and the Chebyshev lowpass prototype is used in its synthesis method. A complex derivation is given in [13] to achieve an even order Chebyshev response.…”