Future handsets will employ uplink carrier aggregation to increase transmit data rates. This can lead to significant receiver desensitization for a number of LTE band combinations, because of the cross-modulation products created by the nonlinearity of antenna switches and duplexers in the RF front end. To mitigate this effect, an all-digital cancellation algorithm is proposed that relies solely on the digital representation of the signals, a peak covariance search for time alignment, and an adaptive distortion canceller. The recursive least squares (RLS) algorithm is used to find the optimal coefficients for the adaptive filter. Employing the distortion canceller improved the signal-to-interference-plus-noise ratio (SINR) and error-vector-magnitude (EVM) of the desired received signal by up to 20 dB.
Abstract-Design techniques are presented for the realization of high-performance integrated interference suppression filters using bond-wire inductors. A new configuration is proposed for mitigating the impact of mutual coupling between the bond wires. A differential low-noise amplifier with an integrated on-chip passive interference suppression filter is designed at 2.1 GHz in a 0.18-m CMOS process, and achieves a transmit leakage suppression of 10 dB at 190-MHz offset. The differential filter uses metal-insulator-metal capacitors and bond-wire inductors and occupies only 0.22 mm 2 . The cascaded system achieves a measured gain of 9.5 dB with a 1.6-dB noise figure and 5 dBm out-of-band IIP 3 and consumes 11 mA from a 2-V supply.Index Terms-Bandpass filter (BPF), bond wires, CMOS, interference suppression, mutual inductance, wideband code division multiple access (WCDMA).
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