LNA and Mixer Designs for Multi-Band Receiver Front-Ends
With the proliferation of wireless standards and frequency bands, the manufacturers of consumer electronics have tried to integrate many features in a single hand-held device. This has given rise to a need for receivers that are compatible with as many standards and frequency bands as possible. Most current integrated multi-band receivers rely on multiple receiver front-ends to process signals at different bands. The major drawback of this approach is that each front-end must be individually optimized, resulting in longer design-time and higher silicon die areas. This is due to the number of circuit blocks and interface complexity. In addition, this type of implementation is highly standard-specific: thus, it is likely that a major redesign would be required if the same topology were used for different standards.
The primary objective of this research is to investigate efficient ways of implementing such a receiver front-end with minimal cost, power consumption, and design complexity. CMOS will be the targeted process technology for this design, due to the opportunities for analog-digital system integration and cost-reduction. Despite its attractiveness, designing a front-end for multi-band operations in deep-submicron CMOS technology is non-trivial. The main challenge lies in maintaining moderate gain, noise figure, and linearity at minimum current consumption across a wide frequency spectrum with the abating supply voltage.
In this work, we investigate and discuss several receiver front-end building blocks and system designs, with a focus on the issues that arise when designing a multi-band receiver front-end. In addition, we propose several circuit building blocks and systems, and implement design prototypes to validate the possibilities. The results suggest that by exploiting high-speed CMOS transistors and innovative low-voltage design techniques, it is possible to design a low-voltage, low-power, wideband receiver front-end path that is capable of processing signals using the proposed architectures.