CMOS Wireless Transceiver Design

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

“…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].…”

“…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].…”

“…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.…”

LC quadrature generation in integrated circuits

“…Therefore this circuit enables considerable reduction in power consumption. Also it makes the double quadrature downconversion scheme [4] much more attractive due to reduced noise in the RF path. The paper discusses the functionality of the circuit and finally a loss compensation method is presented that enables compensation of the on-chip inductor losses.…”

“…Some of these topologies are shown in figure 1 and figure 2. The topologies shown in figure 1 use either the RF or the LO signal in quadrature [3] and the double quadrature topology [4] shown in figure 2 uses both the RF and the LO in quadrature either to loosen the requirements of the quadrature generating circuits or to improve the accuracy of the down converted signals.…”