Low‐phase‐noise transformer‐based top‐series QVCO using GaInP/GaAs HBT technology

Abstract

PCLs, shunt stubs, and unit lines have been modified to count for the fringing capacitance and discontinuity effects [10]. The filter shown in Figure 6 is fabricated on a substrate with a relative dielectric constant of 3.38, a loss tangent of 0.0025, and a thickness of 0.8 mm. The filter is rigorously modeled by emulator IE3D [12]. All final characteristic impedances of transmission-lines are obtained by using an optimization process [13]. The simulation results of designed filter performance of pass band with 21% (2.48 GHz) and 10% (5.25 GHz) for duroid substrate. The bandwidths of each passband are highly matched with the desirable values for the filter. The insertion losses of the filter are about 0.731 and 1.403 dB at the frequences of 2.532 and 5.32 GHz, respectively.The measurements are performed with a HP8510C network analyzer. The measured and simulated performances shown in Figure 7 are well matched. From the experimental results, the 3 dB bandwidths are about 20 and 10% for the frequency of 2.45 and 5.25 GHz, respectively. The insertion loss is about 0.831 dB for the frequency of 2.38 GHz and 1.873 dB for the frequency of 5.216 GHz. The proposed filter has attractive features, including wide bandwidth, low insertion loss, smaller size, and easy mass production. CONCLUSIONSIn this investigation, a mapping method to find the system function of a dualband filter in the z-domain by discrete-time domain techniques as well as by chain-scattering matrices of various transmission-lines is developed. By cascading a band-pass filter and a band-stop filter, a dualband filter with the desired bandwidth and low insertion loss is realized. We derive the chain scattering parameters of various microstrip lines and apply the transfer function of transmission lines to design the dual band filter. The validity of the proposed method has been confirmed through the design, simulation, and measurement of dual-band bandpass filter at 2.45-5.25 GHz on duroid substrates. Our design results of the dualband filter is not only easy implementation but also unlimited application to the mentioned bands. It is sensible that many other circuits developed in the digital signal process can also be implemented by using our nonuniform transmission-line method for microwave applications.