System and circuit design techniques for WLAN-enabled multi-standard receiver
Ling Zhang · OhioLink ETD Center (Ohio Library and Information Network) · 2005
As previous second generation (2G) digital cellular standards, such as GSM, were only oriented to the delivery of speech and low bit-rate data services, the need to support broadband multimedia services over wireless infrastructure (with data rates of up to 2 Mbits/sec) is driving the development of third generation (3G) W-CDMA airinterfaces.With the increasing popularity of Wireless Local Area Networks (WLAN), such as Bluetooth and IEEE 802.11b standards, a WLAN-enabled mobile phone, which will not only transfer voice and multimedia data but also access Internet wherever possible, outlines the scenario of the fourth generation (4G) mobile systems.In addition, WLAN-enabled cell phones are also expected to contain multimode cellular capability.An exploration of WLAN-enabled multi-standard wireless receiver is described in this dissertation.The standards under consideration in this proposal are GSM-900, WCDMA and WiFi (IEEE 802.11b).A GSM/WCDMA/WiFi triple-standard receiver is proposed and analyzed.In this triple-standard receiver, a low-IF (100 kHz) architecture has been used for GSM to reduce the DC offset problem and relax the image rejection requirement while a Zero-IF architecture has been used for the other two standards.Three RF filters have been used to select appropriate signal bands.Due to the proximity of WCDMA and WiFi bands, LNA and mixer have been shared between them, but a second LNA and mixer is necessary for GSM operation.However, when one set of LNA and mixer is xvi 5.4 Noise Shaping for Zero-, First-and Second-order Σ∆ Modulator . .5.5 Block Diagrams of CT (a) and SC (b) Σ∆ Modulator . . . . . . . .5.6 Cascaded Σ∆ Modulator . . . . . . . . . . . . . . . . . . . . . . . .5.7 Single Stage Σ∆ Modulator Examples . . . . . . . . . . . . . . . . .