A 12 bit, 1.3 GHz to 4.7 GHz Switched Current Source RF Power-DAC achieving -47.2 dB EVM for 4096-QAM

Measurement results of a integrated radio frequency power-digital-to-analog converter (RF power-DAC) with high linearity and bandwidth are presented. The power cells operate as switched current sources to increase linearity at low and medium power. The operating mode shifts to current mode class-D at high power to optimize both linearity and efficiency. The RF power-DAC achieves 28.5 dBm peak output power with peak drain efficiency (DE) and system efficiency (SE) of 44.1% and 42.0% at 2.1 GHz. The 3 dB power bandwidth between 1.3 GHz and 4.7 GHz is 3.4 GHz, which corresponds to 113% of relative bandwidth. For a 5 MBd 4096-QAM signal at 2.2 GHz, up to -47.2 dB EVM and -54.3 dBc ACLR can be reached with 18.9 dBm average output power and 11.0% SE. For the entire frequency range, the EVM is at least -41.6 dB, making the RF power-DAC perfectly suited for frequency-agile applications.