A Single–Chip 10-Band WCDMA/HSDPA 4-Band GSM/EDGE SAW-less CMOS Receiver With DigRF 3G Interface and ${+}$90 dBm IIP2

Digitally Assisted Analog and RF Circuits

“…The mismatch calibration mechanisms are indispensable for recent wireless standards. For example, UMTS/LTE direct-conversion receivers require an IIP2 of more than 70 dBm, which is almost impossible without any mismatch calibration for differential blocks [13]. I/Q mismatch is caused by a mismatch between I (in-phase) and Q (quadrature-phase) down/up-conversion signal paths in both amplitude and phase.…”

“…Sometimes, IM2 becomes a serious issue in direct-conversion receivers depending on a required specification such as UMTS/LTE receivers. More than 70 dBm IIP2 is required for WCDMA receiver [13], and even a 1% mismatch degrades IIP2 by 20 dB. More than 40 dBm is usually almost impossible without any calibration due to the PVT variation.…”

“…More than 40 dBm is usually almost impossible without any calibration due to the PVT variation. Mismatch calibration techniques for IIP2 improvement have been reported, and an on-chip automatic IIP2 calibration is reported with the measured +90 dBm IIP2, which is realized by 25-% duty-cycle LO injection and threshold adjust, and current-input complex direct coupled filter [13].…”

Managing linearity in radio front-ends

“…If a first-order high-pass filter is used in the auxiliary path, then the effective transfer function of the combined main and auxiliary paths at the output of the LNA is given by [35], H( jω) = α + β jω/p 1 + jω/p e jφ (2) where α is the gain of the main path, β is the gain of the auxiliary path, ω is the frequency ω in − ω LO , that is the offset frequency relative to the LO frequency, p is the pole frequency of the HPF at baseband, and φ is the phase shift of the auxiliary path relative to the main path. For φ = cos -1 (-α/β ), eq.…”

A low power direct conversion receiver RF front-end with high in-band IIP2/IIP3 and low 1/f noise

“…But different from super-heterodyne receivers, direct conversion receivers require that the RF front-ends have high IIP2 and low 1/f noise since the second-order inter-modulation distortion and 1/f noise contribute low frequency components which would interfere with the useful signals and seriously lower down the sensitivity of the receivers. Although the current-commutating passive mixer technique could be used to improve IIP2 and 1/f noise performance, the high power consumption of the trans-conductance amplifier and the trans-resistance buffer before and after the mixer limits its usefulness, mainly in the high-performance wireless mobile communication systems [1,2].…”