Adaptive gain and delay mismatch cancellation for LINC transmitter

Abstract

LInear amplification with Nonlinear Component (LINC) transmitter architecture is an efficient solution for high efficiency amplification of signals. Nonetheless, this solution suffers both from gain impairment and delay mismatch between the two signal paths. Indeed, a mismatch in propagation time between the paths degrades the quality of the transmit signal but also disrupts the convergence of the gain correction algorithm resulting in a degradation of its performance. In this paper, we present an adaptive algorithm based on a gradient descent formulation for the identification and correction of these delays. We also demonstrate its effectiveness when applied prior to the gain adjustment procedure. The identification approach is preferred here, to ensure monitoring facilities.

An I/Q DAC with gain matching circuit for a wireless transmitter

“…Equation (3) shows that the mobility and threshold voltage shift of PMOS current sources in I/Q DAC directly contribute to current mismatch of the I/Q DAC and results in current errors between the I and Q channels. Pelgrom OE5 gives the random mismatch for the standard deviation of saturation current for two identically sized devices.…”

Gain and delay mismatches cancellation in LINC and polar transmitters

“…It is constituted of the main path with two transmitters in parallel and a return path for correction. It takes into account quantization effects, with 8-bit DACs and 8-bit ADCs at a sample rate of 8F s as detailed in [10]. With the simulation model, the EVM value is 0.3% and ACLR is 43 dB.…”