Many modern communication systems use orthogonal frequency division
multiplexing (OFDM) and discrete multi-tone (DMT) as modulation schemes where
high data rates are transmitted over a wide frequency band in multiple orthogonal subcarriers.
Due to the many advantages, such as flexibility, good noise immunity and the
ability to be optimized for medium conditions, the use of DMT and OFDM can be found
in digital video broadcasting, local area wireless network (IEEE 802.11a), asymmetric
digital subscriber line (ADSL), very high bit rate DSL (VDSL) and power line
communications (PLC). However, a major challenge is the design of the analog frontend;
for these systems a large dynamic range is required due to the significant peak to
average ratio of the resulting signals. In receivers, very demanding high-performance
analog filters are typically used to block interferers and provide anti-aliasing before the
subsequent analog to digital conversion stage. For frequencies higher than 10MHz, Gm-C filter implementations are generally
preferred due to the more efficient operation of wide-band operational transconductance
amplifiers (OTA). Nevertheless, the inherent low-linearity of open-loop operated OTA
limits the dynamic range. In this dissertation, three different proposed OTA linearity
enhancement techniques for the design of high frequency and high dynamic range are
presented. The techniques are applied to two filter implementations: a 20MHz second
order tunable filter and a 30MHz fifth order elliptical low-pass filter. Simulation and
experimental results show a spurious free dynamic range (SFDR) of 65dB with a power
consumption of 85mW. In a figure of merit where SFDR is normalized to the power
consumption, this filter is 6dB above the trend-line of recently reported continuous time
filters.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/5933 |
| Date | 17 September 2007 |
| Creators | Lewinski Komincz, Artur Juliusz |
| Contributors | Silva-Martinez, Jose |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1246798 bytes, electronic, application/pdf, born digital |
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