On the excess thermal noise in short channel MOS transistors

The RF field develops fast today and to meet the increasing needs from more and more users and higher and higher data rates for mobile terminals the number of wireless standards are rapidly increasing. This has lead to an increased number of frequency spectra dedicated for wireless communication, such as the recent ones for WCDMA, Bluetooth, and WLAN. Instead of using one RF front-end for each standard as done today, the need for multiband multistandard front-end receiver architectures will be large in the near future. This is a big step towards software defined radio. This single front-end approach will lead to more flexible receivers to a lower cost for the consumers. Multiband multistandard receivers need circuitry that can adapt to several RF-bands with very varying carrier frequencies and different requirements. For cost effectiveness there should also be a minimum of external components and on-chip passives.One of the most critical components in a multiband multistandard receiver, independent of the receiver architecture, is the low-noise amplifier (LNA). The LNA must be capable of handling several carrier frequencies within a large bandwidth. Therefore it is not possible to optimize the circuit performance for just one frequency band as can be done for a single application LNA. This makes the design task more difficult. Two different circuit topologies that are suitable for multi band multistandard LNAs are:• Wideband LNAs that cover the frequency bands of interest• Tunable narrowband LNAs, tunable over the frequency bands of interestThe main focus of the research has been to develop suitable circuit techniques for such LNAs in silicon technologies (CMOS and BiCMOS) in the frequency range 1-10 GHz with a minimum of passives. Both wideband LNAs and tunable narrowband LNAs based on the principle of active recursive filters have been implemented in both CMOS and BiCMOS technologies.