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This brief presents a complete design flow for a compact low-loss high-selectivity excellent-isolation LTE Band3 (B3) duplexer (TX: 1710 MHz-1785 MHz, RX: 1805 MHz-1880 MHz). The proposed chip duplexer is based on the thin film bulk acoustic resonator (FBAR). In addition to the general design method, the effects of temperature drift, resonator performance distribution on wafer, the quality factor of inductance, device yield, and dissipated power density distribution on the design flow are described. These aspects are of great significance for the batch production of FBAR duplexers in the industry. Samples that pass the above industrial process are selected for testing. Measured results show reasonable consistency with the co-simulation results. 1.2/1.0-dB minimum IL in TX /RX band, 20-dB rejection in 3.5 GHz (second harmonic of TX), and more than 50 dB isolation in both TX and RX frequency are achieved with less massload simultaneously. [ABSTRACT FROM AUTHOR]

An extremely wideband hybrid bandpass filter (BPF) with high selectivity and low insertion loss is proposed in this brief. The hybrid BPF is composed of three coupled lines (CLs), six matching transmission lines (TLs) and two film bulk acoustic resonator (FBAR) networks with ladder-type structure. These two FBAR networks can help greatly enhance the upper and lower sideband roll-off of the hybrid BPF. At the same time, the passband is compensated by CLs and TLs. The odd-even mode theory is used to analyze the hybrid BPF to obtain the analytical solutions. Through electromagnetic-acoustic co-simulation and optimization, a hybrid BPF with extremely wideband is fabricated and measured. A discussion on the deviation between the simulation and the measured results is presented. The measured hybrid BPF has a 3-dB fractional bandwidth of 56 %, a minimum insertion loss of 1.733 dB and a shape factor of 0.83 simultaneously. [ABSTRACT FROM AUTHOR]

A hybrid wideband filter composed of two sections with sharp frequency selectivity is proposed in this article. The first section consists of a coupled line (CL), two transmission lines (TL), and a film bulk acoustic resonator (FBAR) with lower frequency. This section mainly controls the lower roll-off. The other section is composed of two CLs and two FBARs with higher frequencies. This section mainly controls the roll-off of the upper band. The insertion loss and rejection outside the passband are well controlled because of the CLs. The analysis of the proposed filter is realized by combining microwave network theory with a modified Mason model for FBAR. Through analytical analysis, conditions for generating transmission zeros and poles are obtained. The methods of enhanced out-of-band rejection and bandwidth control are proposed through FBAR networks and tuning of FBARs, respectively. To verify the proposed theory, a wideband filter with a central frequency of 2.14 GHz is designed, simulated, and assembled. The FBARs, TLs, and CLs are assembled through a 1-mil wire bond technique. The measured results show good consistency with the simulation results; 24.9% of 3-dB relative bandwidth, 1.87-dB in-band insert loss, and an excellent 0.91 shape factor are obtained. [ABSTRACT FROM AUTHOR]

A generalized method for the extraction of longitudinal parameters of materials in a film bulk acoustic resonator (FBAR) is proposed in this brief. Based on the simplification of the equivalent circuit of a Mason model, a compact step impedance resonator (SIR) model without loss resistors or static capacitors is obtained. The resonance of the acoustic layer is also expressed through the resonance condition of a SIR model analytically. Innovatively, the simplified model is used to fit the parallel resonance frequency (${f} _{\mathrm{ p}}$) of different measured FBARs on a same wafer. Combined with the stack information of five cross section samples and the measured ${f} _{\mathrm{ p}}$ , longitudinal acoustic velocities and densities of AlN and Mo is extracted. The fitted resonance frequency of the simplified model is compared to the measured ${f} _{\mathrm{ p}}$ , and the maximum frequency offset is controlled within 6 MHz. In addition, the extracted material parameters are compared with the reference values and show great matching. This brief analytically reveals the correlation between material parameters and ${f} _{\mathrm{ p}}$ , and the proposed method is useful for accurate frequency fitting and parameter extraction. [ABSTRACT FROM AUTHOR]

In this article, a 1.7–2.6-GHz broadband power amplifier (PA) was proposed using the generalized quasi-Chebyshev lowpass matching approach, which was directly composed of step-impedance transmission lines (SITLs). First, the complete design theory for the introduced step-impedance matching network was provided with the detailed design equations. The impedance of the SITLs can be calculated directly based on the specified bandwidth, maximum allowable return loss, and impedance-transforming ratio. The electrical length of SITLs was utilized to adjust the harmonic impedances to perform a PA high-efficiency region. For demonstration, a PA using the 10-W gallium nitride high electron mobility transistor (GaN HEMT) with the measured drain efficiency (DE) of 65%–78% from 1.7 to 2.6 GHz was achieved. A good agreement between the simulated and measured results can be observed. [ABSTRACT FROM AUTHOR]

Corona current measurement is essential for research into corona discharge under ultra high-voltage direct-current (HVDC) environment. The sensor is extremely important due to the small (microampere) amplitude of the corona current and the wide (dc to tens of megahertz) range in frequency. In this paper, a high-frequency sensor is described, and its application is introduced for accurate measurement of corona current under HVDC environment. Based on the finite-element method and the charge simulation method, the structure of the sensor is determined considering a \pm1200-kV environment. The sensor is immune to the effects from the external environments such as vibration and temperature changes. Results indicate that the sensor is feasible for corona current measurement. [ABSTRACT FROM PUBLISHER]