We present a unified charge-based model for double-gate and cylindrical architectures of junction fieldeffect transistors (JFETs). The central concept is to consider the JFET as a junctionless FET (JLFET) with an infinitely thin insulating layer, leading to analytical expressions between charge densities, current, and voltages without any fitting parameters. Assessment of the model with numerical technology computer-aided design simulations confirms that holding the JFET as a special case of the JLFET is justified in all the regions of operation, i.e., from deep depletion to flat-band and from linear to saturation. Index Terms-Cylindrical gate all around junction fieldeffect transistor (JFET), double-gate FETs, nanowire FETs, power semiconductor FETs, radiation-hard electronics, vertical JFET (V-JFET).