A compact substrate integrated waveguide (SIW) filter based on composite right/lefthanded (CRLH) resonator units is implemented in this paper. The filter is composed of two CRLH resonator units serially connected by a SIW transmission line unit. The structure of the filter and equivalent circuit transmission behavior are analyzed, and a novel design method by optimizing the length and width of the interdigital metal slots to decrease the filter operation frequency is proposed. To further demonstrate the design theory and performance of the proposed filter, the filter was designed and fabricated on an RT6010 dielectric material. The measurement results show that the proposed filter works at a center frequency of 5.8 GHz with 200 MHz bandwidth The insertion loss is 2.3 dB, and the filter size is only 10 mm × 7.4 mm.
A pre-distortion linearized Darlington cascode power amplifier cell is explored for broadband amplifier implementation, with additional inclusion of a RLC peaking network at the base terminal of the cascode transistor, and a RC feedback network at the input Darlington transistor. The RLC peaking network optimizes bandwidth and large signal power gain. The RC feedback network simplifies the design of broadband matching for the input Darlington pair. Most importantly, an optimization method of the input Darlington transistor biased at saturation mode is proposed to function as a predistortion linearizer, which can compensate for gain compression and phase deviation effects of the following cascode power stage. With this compensation technique, the proposed broadband PA operating over a frequency range from 0.2 to 6 GHz achieves higher OIP3 than the conventional Darlington cascode amplifier, resulting in a 5 dB improvement of OIP3 at 6 GHz. A P1 dB ranging from 24 to 27 dBm over the frequency range is achieved by this broadband power amplifier with a 0.27 mm 2 InGaP/GaAs HBT chip die.
In the RF (Radio Frequency) front-end of a communication system, bandpass filters (BPFs) are used to send passband signals and reject stopband signals. Substrate-integrated waveguides (SIW) are widely used in RF filter designs due to their low loss and low cost and the flexibility of their integration properties. However, SIW filters under 6 GHz are still too large to meet the requirement of portable communication devices due to their long wavelength. In this paper, a very compact fully integrated SIW filter is proposed and designed with RT6010 dielectric material to meet the small size requirement of portable devices for next-generation sub-6 G applications. The proposed filter contains two sawtooth-shaped composite right-/left-handed (CRLH) resonator units, instead of traditional rectangular-shaped CRLH resonator units, which makes the filter more compact and cost effective. The filter is designed and fabricated on an RT6010 substrate, with a size of only 10 mm × 7.4 mm. The measurement results illustrated that the proposed BPF shows a passband covering the frequency range of 3.25–3.45 GHz; the minimum passband insertion loss is only 2.4 dB; the stopband rejection is better than −20 dB throughout the frequencies below 3.0 GHz and above 3.8 GHz; S11 is as low as −37 dB at 3.35 GHz; and the group delay variation is only 1.4 ns throughout the operation bandwidth.
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