Hans Hagberg

A 9-band WCDMA/EDGE transceiver supporting HSPA evolution

The future of cellular radio ICs lies in the integration of an ever-increasing number of bands and channel bandwidths. Figure 21.2.1 shows the block diagram of our transceiver, together with the associated discrete front-end components. The transceiver supports 4 EDGE bands and 9 WCDMA bands (I-VI and VIII-X), while the radio can be configured to simultaneously support the 4 EDGE bands and up to 5 WCDMA bands: 3 high bands (HB) and 2 low bands (LB). The RX is a SAW-less homodyne composed of a main RX and a diversity RX. To reduce package complexity with so many bands, we chose to minimize the number of ports by using single-ended RF interfaces for both RX and TX. This saves several package pins, but requires careful attention to grounding. The main RX has 8 LNA ports and the diversity RX has 5, with some LNAs supporting multiple bands. On the TX side, 2 ports are used for all EDGE bands and 4 for the WCDMA bands.

Sensitivity Degradation in a Tri-Band GSM BiCMOS Direct-Conversion Receiver Caused by Transient Substrate Heating

An analysis of transient thermal substrate effects impairing the sensitivity of the DCS path in a tri-band GSM/DCS/PCS BiCMOS radio receiver is presented in this paper. A simple thermal model of the substrate is employed, enabling concurrent electrothermal circuit-substrate simulations within a standard analog circuit simulator. Simulation results obtained with this approach match very closely the measured data, and are used to predict the sensitivity of different circuit layout configurations to thermal gradients in the substrate. Following the guidelines suggested by these analyses, a redesigned version of the receiver displays a sensitivity improvement of 2 dB to 4 dB.