Classical and modern receiver architectures

Abstract

This article is a review of several classical and modern wireless receiver architectures used in wideband wireless communication systems. The emphasis is on configurations suitable for integration on a single silicon chip. A full understanding of the design trade-offs discussed in this article is necessary for the proper introduction of a new modulation scheme presented in the companion article, "Hierarchical QAM: A Spectrally Efficient DC-Free Modulation Scheme" [1].

A Novel Approach to Blind I/Q Mismatch & Carrier Offset Compensation

“…Complete elimination of the IF stage results in highly simplified structure, the so-called direct-conversion receiver, where most of the channel selectivity and amplification are implemented at baseband [1,2]. Firstly, since most of the signal processing tasks take place at low frequencies, the power consumption is minimized.…”

“…Since, in theory, the I/Q downconversion corresponds to a pure frequency translation, the fundamental image signal problem is basically avoided during the downconversion. In thismanner, the requirements for RF image rejection filtering are greatly relaxed in practice [1][2][3][4].…”

“…Instead, alternative receiver structures, like the direct conversion [1,2] and low-IF [1,3,4] architectures, are receiving more and more interest. The analog front-end of these types of receivers is partially based on complex or I/Q signal processing [5][6][7].…”

“…The down-conversion is usually done with a simple real mixer, and the spectral components on the image signal band need to be attenuated sufficiently by the RF stages before the mixer. Due to the high number of discrete components and high power consumption, the superheterodyne architecture is, however, not the most appropriate choice for highly integrated implementations [1][2][3][4].…”

“…In traditional receiver designs, these tasks are implemented more or less independently of each other, aiming at close-to-ideal operation in each signal processing stage. This has lead to the use of the superheterodyne receiver architecture [1,4] in order to meet the tight RF specifications in terms of image band attenuation and nonlinear effects of the receiver front-end stages. In such receivers, the RF signal is first downconverted to a fixed intermediate frequency (IF) where the receiver selectivity is implemented using a fixed IF filter.…”