16 - 4

Although many efforts have been exerted, implementation of fully integrated chip for TV tuner application is still a great challenge, to the standard of DVB-C (50M-860MHz) for example. Recent works on wideband LNA [1-2] based on off-chip balun have shown good performances, such as low NF, high linearity and excellent input matching. However, the off-chip balun adds extra cost, loss and much PCB size; meanwhile, an on-chip passive balun may account for large die area and not be acceptable for low frequency and wideband applications. Thus, a single-to-differential stage (S2D) [3-6] is adopted in order to replace the balun for less area and cost without degrade the performances. Ref [3] has made S2D a part of the RF front-end, however, an off-chip inductor is applied and performance analysis of the S2D is not given. In [6], a balun-LNA is presented with excellent performances for less gain and phase error, but it can not maintain the performances at 50MHz and in high input levels situation; a capacitive attenuator is employed in [9], but it needs an extra circuit for input matching and the scheme requires one Gm-stage for each attenuation. In this paper, a fully integrated wideband LNA based on S2D with resistive attenuator for TV tuner applications is implemented. A double-conversion low-IF (DLIF) DVB-C tuner RF architecture is shown in Fig.1. The LNA based on S2D stage is used as a replacement of traditional scheme which employs differential LNA with an off-chip balun.