4.5 A Reconfigurable, Multi-Channel Quantized-Analog Transmitter with <-35dB EVM and <-51dBc ACLR in 22nm FDSOI

The presence of multiple operative modes and standards in 5G/6G systems set two crucial requirements for the next generations of wireless transmitter (TX): flexibility and high spectral purity. While the former can be obtained by more digital systems such as a radio-frequency digital-to-analog converter (RF-DAC) TX [1, 2], mixer-based solutions still outperform RF-DACs in terms of spectral purity for a given power dissipation [3, 4]. The reason is that RF-DACs need a very large number of bits (up to 18bits) to lower the quantization noise, and a very high sampling rate to meet the spectral purity required by 5G/6G TXs [2]. This work aims to find a compromise between RF-DAC and analog-based TXs by using the Quantized Analog (QA) signal processing presented by Musayev et al. [5]. The signal is sliced in amplitude to feed an array of analog TXs, and recombined after the upconversion (Fig. 4.5.1). While keeping similar spectral purity as analog TXs, this approach has a higher level of flexibility by enabling multi-carrier operation, power scalability and an agile reconfiguration of the class of operations. Moreover, it will be shown how the QA approach is a very competitive solution in terms of area and power dissipation compared to RF-DAC-based solutions.