A Mixed-Signal Circuit Technique for Cancellation of Interferers Modulated by LO Phase-Noise in 4G/5G CA Transceivers
Sprache des Titels:
In RF transceivers operating in carrier-aggregation, spurs are generated on the transceiver chip which may downconvert any blocker signal located at the spur frequency into the receiver baseband. The blocker signal could either be the transceiver?s own transmit signal when operating in frequencydivision duplex, or a WiFi-related signal received by the antenna. This so-called modulated spur interference contains the phase noise (PN) of the involved local oscillator harmonics which created the spur and leads to a degradation of the wanted RX signal. The presented mixed-signal circuit mimics the spur building law including the PN of the harmonics and is, therefore, able to provide a replica of the spur interference including PN modulated components. This replica is then used as a reference signal for the digital cancellation of the main and image modulated spur interference using a widely-linear (WL) cancellation structure. The proposed circuit technique is implemented in
28 nm LP CMOS technology, and measurement results show that the mixed-signal solution outperforms a digital-only WL cancellation with respect to PN cancellation even with high blocker power levels of ?15 dBm at the input of the low-noise amplifier.
Sprache der Kurzfassung:
IEEE Transactions on Circuits and Systems I: Regular Papers