Digital Compensation for Analog Front-Ends: A New Approach to Wireless Transceiver Design

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Real Life Front-Ends

The physical layer implementation of almost any modern wireless device consists of three main parts (Figure 3.1): the antenna, the analog part of the transceiver and the digital part of the transceiver. In this chapter, we focus on the analog part of the transceiver, which we will often refer to as the ‘front-end’. We want to describe the main front-end architectures used in modern designs and their main functional blocks. The aim of this description is to highlight the deviations from the ideal behavior of these blocks and to describe this deviation by an equivalent lowpass model, which will be complex when necessary. We will include in this analysis the analog-to-digital and digital-to-analog converters that are actually at the interface between the analog and the digital sections. Note that we will restrict this analysis to bandpass signals, i.e. systems where:

• the modulation/demodulation is performed digitally, although many concepts also apply to analog modulation/demodulation;
• the signal is modulated on a high frequency carrier and the modulation bandwidth is significantly smaller than the carrier frequency, such that complex modulation is possible.

  

  Figure 3.1 Simple partitioning of a wireless device (PHY part only).

We will first describe the main radio frequency (RF) architectures in Section 3.1. We will classify them according to the number of frequency ...