Linearity characterization of RF circuits through an unequally spaced multi-tone signal

An Unequally Spaced Multi-Tone signal (USMT) is used for the assessment of nonlinear devices and circuits. The statistical properties of the signal are described. The setup measurements for such a signal are given either by using a Large Signal Network Analyzer (LSNA) or a Nonlinear Vector Network Analyzer (Keysight PNA NVNA with SA option). A USMT Load Pull (USMT-LP) set-up has been developed using a LSNA and it is shown how to extend this set-up to a NVNA receiver. The set-up is fully on-wafer calibrated at all the frequencies of interest. The USMT-LP set-up is configured to make measurements with USMT signals up to eight frequencies and allows measuring simultaneously the MT output power, gain, Power Added Efficiency (PAE), Carrier to Intermodulation (C/I) ratio or Noise Power Ratio (NPR) in order to derive the Error Vector Magnitude (EVM) induced by the device.