Conference Paper

A 400-to-900 MHz receiver with dual-domain harmonic rejection exploiting adaptive interference cancellation

Univ. of Twente, Enschede, Netherlands
DOI: 10.1109/ISSCC.2009.4977393 Conference: Solid-State Circuits Conference - Digest of Technical Papers, 2009. ISSCC 2009. IEEE International
Source: IEEE Xplore


Wideband direct-conversion harmonic-rejection (HR) receivers for software- defined radio aim to remove or relax the pre-mixer RF filters, which are inflexible, bulky and costly. HR schemes are often used, but amplitude and phase mismatches limit HR to between 30 and 40 dB. A quick calculation shows that much more rejection is wanted: in order to bring harmonic responses down to the noise floor (e.g. -100 dBm in 10 MHz for 4 dB NF), and cope with interferers between -40 and 0 dBm, an HR of 60 to 100 dB is needed. Also in terrestrial TV receivers and in applications like DVB-H with co-existence requirements with GSM/WLAN transmitters in a small telephone, high HR is needed. In this work, an architecture aiming for >80 dB HR is shown. It consists of an analog front-end followed by adaptive interference cancellation (AIC) in the digital domain. AIC is known for its ability to adapt to and mitigate unknown system non-idealities, e.g. gain and phase imbalances. Due to its adaptivity it can achieve large improvements, provided the interference estimate is accurate. To the authors' knowledge, they are the first to explore AIC for HR and previously presented simulation results. Here a new and different architecture and measured results with the RF part implemented in 65 nm CMOS and the AIC in software are presented.

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    • "However, to overcome the problem of LO harmonics with an HRM regarding digital TV requirements, HRM needs many sub-mixers and phase-shifted LOs that make HRM intricate and impossible (Shah, 2009). Over 60 dB rejection is obtained by employing a harmonic rejection stage for third and also fifth LO harmonics (Moseley et al., 2009). However, it makes the system complicated. "
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    • "By contrast, a radio targeting the range of 900 MHz to 5 GHz (cellular to WLAN bands) must deal with harmonics up to the fifth or sixth order. For this reason, such radios have focused on harmonic-reject mixers (HRMs) [14]–[16] derived from the original concept in [17]. Cognitive radios do not easily lend themselves to harmonic-reject mixing. "
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    • "Both improve HR by rejecting harmonics in two successive steps ( " iterative " ), and both share the same 8-phase RF-to-baseband downconverter as a first HR stage. Compared to [17]–[19], we greatly extend the analysis and show additional experimental results. Compared to [20], this work derives the interference estimate in another way, presents measurements and achieves better performance due to the better interference estimate. "
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