All digital compensation scheme for spur induced transmit self-jamming in multi-receiver RF frond-ends

Abstract

In radio receivers employing diversity reception, receiver LO frequencies are closely separated. Different LO frequencies can couple through the substrate to the nonlinear components in the phase locked loops thus generating spurs. Such a spur, if it falls nearby the local transmit frequency, can inadvertently demodulate the strong local transmit signal and hence degrade the received SNR severely. In this paper, we investigate a novel method of compensating for transmitter selfjamming by carefully mimicking this mechanism in the received signal path and thus allowing cancellation. It has been shown that with certain simplifying assumptions one can realistically cancel the spur-induced transmit self-jamming interference. We outline the theoretical feasibility of this approach and then setup an RF test-bench to demonstrate these ideas on actual RF chipsets. Performance results from prototype measurements are reported.

All-Digital Cancellation Technique to Mitigate Receiver Desensitization in Uplink Carrier Aggregation in Cellular Handsets

“…Unfortunately, direct estimation of the filter coefficients of and is difficult due to the nonlinear dependency of the parameters. Following the logic of [10], the input-output relationship of the MISO filter can be written as (6) where is the modeling error, e.g., caused by noise. Using the following notation:…”

“…Alternatively, one could take advantage of the deterministic nature of the sources of self-jamming and employ digital cancellation techniques to mitigate the receiver desensitization [4]- [6]. These digital cancellation techniques are limited to a single source of self-jamming.…”

All-digital cancellation technique to mitigate self-jamming in uplink carrier aggregation in cellular handsets

“…Therefore, an algorithm is proposed using an adaptive digital filter to cancel the distortion. Different sources of selfjamming have been similarly compensated in [2,[5][6].…”