A Theoretical Investigation into the Limits of Bandwidth Enhancement with the Asymmetrical Bridged T-Coil Network.

This paper presents the results of a theoretical investigation of the asymmetrical bridged T-coil (BTC) bandwidth enhancement network under the condition of maximally flat magnitude (MFM) response. Conventionally, the BTC is used in the symmetrical configuration and it is well known that, as compared to the commonly used RC load, the maximum bandwidth enhancement ratio (BWER) under the MFM condition is 2√2. It is shown here that by introducing asymmetry, even under the constraint of MFM response, the maximum achievable BWER is theoretically unlimited, the limit being set only by practical considerations. Unlimited BWER has never been considered possible, even theoretically, with BTC or any other network, and the result reported here is believed to be a breakthrough in the design of wide-band and ultra wide-band amplifiers. Simulations for a few designs indicate that practical realization of the full potential of the asymmetrical BTC may have to wait for improved technologies which facilitate tight coupling between the two parts of the coil and also minimize parasitic effects. [ABSTRACT FROM PUBLISHER]