A new nonballistic analytical model for the intrinsic channel region of MOSFET-like single-walled carbon-nanotube FETs (CNTFETs) with ohmic contacts has been developed which overcomes the limitations of existing models and extends their applicability toward high bias voltages needed for analog applications. The new model comprises an improved description of the electron-phonon scattering mechanism, considering the accumulation of electrons at the bottom of conduction subband due to back scattering by optical phonons. The model has been justified by a Boltzmann transport equation solver. The simulation results are found to be in agreement with the experimental data for highly doped CNTFETs.