ENIDH – EEM - Engenharia Eletrotécnica Marítima
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Browsing ENIDH – EEM - Engenharia Eletrotécnica Marítima by Author "Assunção, Mário"
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- Analysis and Design of Current Mode Class-D Power Amplifiers With Finite Feeding InductorsPublication . Silva-Pereira, M.; Assunção, Mário; Vaz, João CaldinhasCurrent-mode class-D (CMCD) power amplifiers (PAs) may not achieve a switching efficiency as good as class-E PAs, but they require fewer inductances and deliver almost five times more power for the same load and supply voltage when compared with the ideal push–pull class-E PA. Furthermore, CMCD PAs can easily use bondwires as the only circuit inductors, a precious feature that Internet-of-Things (IoT) wireless interfaces can exploit. For this reason, we analyze the voltage and current waveforms in CMCD PAs without assuming infinite value feeding inductors (i.e., without choke inductors). It is shown that the current stress on the switching device is significantly higher than in the conventional topology, especially in bondwire-based designs where relatively small feeding induc tances are presented. Finally, we propose a design procedure for a given feeding inductance that maximizes energy efficiency while delivering a compact-size solution. A 2.4-GHz PA capable of delivering 19.8 dBm to a 100-Ω differential load with a power added-efficiency (PAE) of 58% is presented. Three-dimensional electromagnetic (3-D EM) simulations combined with postlayout simulations were used to evaluate the PA performance in a quad-flat nonlead (QFN)-type package. The circuit is designed in a 0.13-μm process and only occupies a silicon area of 0.025 mm2.
- Lumped Model for CMOS Interconnections linesPublication . Assunção, Mário; Santos, Pedro; Freire, João CostaA study on CMOS interconnections lines up to 40GHz is presented. The lines propagation constant γ and impedance characteristic Z0 are obtained from the measured S parameters up to 40 GHz, on test structures with different lengths, with or without metal ground plane. The values of the well-defined transmission line RLGC lumped model elements per unit length for each measured test interconnection lines are obtained. Although, the RLGC elements values are frequency dependent, we show that using constant values in a wideband, from 5 GHz to 40 GHz, the interconnections model is in good agreement with the experimental S parameters, validating the modelling technique. As expected, for shorter lines, one RLGC section is adequate to attain a good agreement with measured values. However, for longer lines, the number of RLGC sections must be increased. For low frequencies the accuracy is better for interconnections lines with metal ground plane. However, for high frequencies (f > 15 GHz) the accuracy is good for both type of interconnection lines.
- A technique to reduce on-wafer measurements uncertainty on multiline method for CMOS Transmission Lines characterizationPublication . Assunção, Mário; Santos, P.; Freire, J. C.An improvement to the L-L method for Si monolithic Transmission Line (TL) parameter extraction is presented. The propagation constant γ and characteristic impedance Z0 are obtained from cascaded ABCD matrices using on-wafer measurements up to 40 GHz. It is shown that the L-L method matrices processing is strongly dependent on the access variations as different pairs of measurements lead to different extracted TL parameters. Associating three different TLs lengths test structures measurements matrices, which theoretically point to an identity matrix, a technique is proposed to obtain the best set of three measurements with the most similar accesses. The deviation from the ideal identity matrix indicates the access variations. The suggested technique was implemented with TL structures fabricated on a 130 nm CMOS process. When using the best set of three different TL length measurements, the extracted γ and Z0 parameters are almost independent on the TL pair used.