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We analyze a Π-network for tunable antenna impedance matching in 4G mobile communications. Fundamental limits on designability and practical limits on implementation of the network are presented. The performance of the network is evaluated in terms of coverage (the area on Smith chart that can be matched) and the maximum achievable tuning bandwidth. We also derive the required component values and...
A thorough analysis of the tank quality factor in LC oscillators using switched capacitor banks has been carry out taking into account the contribution of the switched capacitances in the off state. Analysis results, confirmed by circuit level simulations, clearly show that the contribution of the switched capacitances in off state strongly affects the quality factor of the capacitor bank, and thus...
This paper reports a new programmable Gm-C-OTA integrator and filter, which allows on-chip periodic analog signal generation and in essence, fulfils the function of the D/A converter. The method has the attributes of digital programming and control capability, robustness and reduced area overhead, which make it suitable for built-in self-test applications. The circuit has been fabricated in standard...
This paper presents a novel MEMS comb-structured variable capacitor at 20 GHz that features a wide capacitance tuning range of 200%, yet avoids unwanted coupling through the springs. This new varactor consists of three comb structures - two of which are anchored to the substrate, while the third, which capacitively couples the two anchored ones, is movable, suspended on mechanical springs. This new...
This paper reports a MEMS tunable capacitor with a new actuation principle. The new design adopts electrostatic actuation of an electrically floating movable dielectric. This enables us to achieve a high Q factor by eliminating the loss associated with springs in the RF signal path. Also, the design can achieve a high tuning range, by using additional actuation combs and thus eliminating the pull-in...
The design and characterization of a CMOS-MEMS variable capacitor is presented. Measured results demonstrate a tuning ratio of 6.9:1, a quality factor of 28 at 3 GHz, and a self-resonant frequency of 11 GHz, with sub-50 fF parasitic capacitance. Simulations of two frequency-reconfigurable circuits, a low-noise amplifier and a power amplifier, show the importance of low parasitic capacitance for practical...
This paper presents a miniaturized 2.5 GHz frequency source based on compensated BAW resonator with its integrated temperature molybdenum sensor assembled on the differential Colpitts oscillator. The presence of silicon dioxide layer having a positive temperature coefficient compared to other layers is used to reduce the resonator's drift. A demonstration oscillator achieves a frequency drift of 40...
The ability of adjustment of the central frequency of a Gm-C resonator in GaAs technology is discussed. First, it is shown that whatever the technology, the desired quality factor can be reached through an appropriate sizing of the transconductance values, by adding an external feedback capacitor in the transconductance amplifiers. Then, it is demonstrated that the adjustment of the central frequency...
This paper presents a low power, low phase noise mm-wave voltage controlled oscillator. The VCO can be tuned from 41 to 44.5 GHz (8% tuning range) and utilizes a differential tuning mechanism based on varactors and fixed MIM capacitors. Fabricated in a bulk CMOS 65 nm technology, it consumes 3.6 mW and exhibits a phase noise of -106 dBc/Hz at 1 MHz offset from a 41.2 GHz carrier. The resulting FOM...
The design and operation technique for a stable capacitance control in piezoelectric RF MEMS tunable capacitors have been investigated. Four folded-beam capacitors composed of piezoelectric aluminum nitride thin films were integrated in the quadruple capacitor and each folded-beam capacitor showed uniform operation voltage of less than 3V. A stable multi-step capacitance control was realized with...
A novel compact coupled planar resonator (CCPR) based VCO (voltage controlled oscillator) using mode-coupling technique was developed in response to expensive high Ceramic and SAW resonators based signal source for wireless communications. One of the problems related to the conventional Ceramic/SAW based resonators (with high Q and low phase noise) is the challenge for integration in IC form. Instead...
The next generation of wireless communication is a ubiquitous radio system concept, providing wireless access from short-range to wide-area, with one single reconfigurable and adaptive system for all envisaged radio environments. This paper presents the design approach of RCO (reconfigurable concurrent oscillator) that simultaneously generates two or more signals of different frequencies that eliminate...
The design, fabrication and measurement of a continuously tunable RF MEMS capacitor is described. The capacitor's dual gap height architecture allows for electrostatic tuning with low resistive loss and a large tuning range. A new dual tuning scheme is introduced for use with two voltage sources. This dual tuning, coupled with a stress-induced bridge, is used to reach further device tuning. Measurements...
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