Development Of Inductively-Degenerated Lna For W-Cdma Application Utilizing 0.18 um Rfcmos Technology

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Date
2009-01
Authors
Mohd Noh, Norlaili
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Abstract
A detailed and systematic methodology on the design of the inductivelydegenerated cascode LNA, also known as the Simultaneously Noise and Input Matching (SNIM) LNA, for Wideband-Code Division Multiple Access (W-CDMA) Direct- Conversion Receiver (OCR) is presented in this thesis. The operating frequency was 2.14 GHz with a supply voltage of 1.8 V and implemented on Silterra's O.18-J..lm 6- metal 1-poly RF CMOS process. This is followed by comprehensive circuit analysis, design methodology and performance comparisons of the modified SNIM, namely the Power-Constrained SNIM (PCSNIM), Current-Reuse (CR) and Folded-Cascode (FC) LNAs. Results show that for applications with low voltage requirement, the FC offers good linearity at a comparable NF. However, the trade-off is the gain. CR and matched SNIM are comparable in all of the performance metrics, but matched SNIM posed a disadvantage in term of space. Under similar simulation conditions, the PCSNIM was able to reduce the NF of the SNIM by 37%, proving the effectiveness of adding a capacitor at the tr!3nsistor's input. A new modified PCSNIM with output buffer was designed to maintain the matched conventional PCSNIM noise figure (NF) merit over the SNIM, but with much less layout space consumed than by the latter. The power gain of the LC-matched SNIM, LC-matched PCSNIM and the new modified PCSNIM with output buffer are comparable but both PCSNIM lost in term of linearity. However, the new modified PCSNIM with output buffer will be better for circuit integration as it requires less space. 5 12 of better than -30 dB was recorded for every LNA topology in this work and this shows that the cascode configuration is able to to provide good reverse isolation. Detailed voltage gain, 5-parameters and noise derivations for the SNIM LNA are provided in this thesis.ยท The derivations for the voltage gain and 5- parameters were implemented using Matlab, verified with the simulation results xxxiii generated by Cadence SpectreRF. The transistor's width for all the topologies except CR was determined at 290 Ilm using the power-constrained noise optimization (peNO) method. Comprehensive analysis on the extreme or corner condition effects on the SNIM LNA performance is provided in this thesis. Two types of post-layout simulations were performed, they were the distributed resistance-parasitic capacitors-coupling capacitors and lump parasitic. Comparisons and analysis were made on the pre- and post-layout simulations and measurement results, and the postlayout results were found to better resembling the results obtained from the measurement in most cases.
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Systematic methodology on the design of the inductivelydegenerated cascode LNA, , for Wideband-Code Division Multiple Access (W-CDMA) Direct- Conversion Receiver
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