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
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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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Keywords
Systematic methodology on the design of the inductivelydegenerated cascode LNA, , for Wideband-Code Division Multiple Access (W-CDMA) Direct- Conversion Receiver