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Abstract: High‐performance, wideband three‐stage power splitters based on substrate integrated waveguide (SIW) are presented. Broadband‐tapered microstrip transitions are used for feeding the SIW structures, which provide 7.5 GHz bandwidth from 21.5 to 29 GHz with return loss below −20 dB. In addition, various T junctions are tuned, not only to provide broadband performance up to mm‐wave frequencies but also offer low‐phase and amplitude imbalance when cascaded in multistage 1 × 8 splitters. 1 × 4 and 1 × 2‐T junctions are adjusted through parametric analysis to provide wide bandwidth of 3.5 GHz at 24.5 GHz and −15 dB reflection coefficient. The optimal microstrip transitions and T junctions are used to design a broadband, eight‐way power splitter with 15 dB return loss from 23.0 to 26.4 GHz and phase and amplitude imbalance of ±2.5° and ±0.8° dB, respectively. Furthermore, optimum positions of all inductive posts in terms of guided wavelength are also provided for assisting the direct design of mm‐wave, high‐performance power splitters. [ABSTRACT FROM AUTHOR]

ABSTRACT A two-stage mm-wave variable-gain amplifier is designed and implemented in a 65-nm CMOS technology. A fully symmetric layout has been utilized to suppress the odd-mode of propagation and increase the quality factor in co-planar waveguide transmission lines. Moreover, a new design technique is proposed for implementing decoupling capacitors for mm-wave frequencies. Body-biasing technique is utilized to change the amplifier gain without significant change in the overall power consumption of the circuit. The measurement results show that the amplifier achieves a peak gain of 10 dB with a gain variation range of 25 dB while consuming 12 mW from a 1.2-V supply. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:470-477, 2014. [ABSTRACT FROM AUTHOR]

In this article, we discuss stability issues for mm-wave monolithic integrated power amplifiers using InP double heterojunction bipolar transistor (DHBT) technology tar-geting E-band applications at 71-76 GHz and 81-86 GHz. Different stability detection meth-ods based on the classical two-port K-As pair, linear three-port graphical analysis, system identifications, circuit modal analysis, and normalized determinant function are all reviewed. The corresponding techniques are employed to predict the occurrence of instabil-ity at IS GHz observed during measurements on a fabricated monolithic microwave inte-grated circuit power amplifier. Experimental results from a redesigned power amplifier with improved stability are presented to confirm that the previously detected oscillation loop is removed using odd-mode stabilization resistors with the correct choice of values and locations. [ABSTRACT FROM AUTHOR]

In this article, we discuss stability issues for mm-wave monolithic integrated power amplifiers using InP double heterojunction bipolar transistor (DHBT) technology targeting E-band applications at 71-76 GHz and 81-86 GHz. Different stability detection methods based on the classical two-port K-Δs pair, linear three-port graphical analysis, system identifications, circuit modal analysis, and normalized determinant function are all reviewed. The corresponding techniques are employed to predict the occurrence of instability at 15 GHz observed during measurements on a fabricated monolithic microwave integrated circuit power amplifier. Experimental results from a redesigned power amplifier with improved stability are presented to confirm that the previously detected oscillation loop is removed using odd-mode stabilization resistors with the correct choice of values and locations. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 662-674, 2013. [ABSTRACT FROM AUTHOR]