The paper presents two novel realizations of voltage-mode first-order all-pass filters. Both circuits use single universal voltage conveyor (UVC), single capacitor, and two grounded resistors. Using the two NMOS transistors-based realizations of the electronic resistor with two symmetrical power supplies, presented all-pass filter circuits can be easily made electronically tunable. Proposed filter structures provide both inverting and non-inverting outputs at the same configuration simultaneously and they have high-input and low-output impedances that are desired for easy cascading in voltage-mode operations. The non-idealities of the proposed circuits are also analyzed and compared. The theoretical results of both circuits are verified by SPICE simulations using TSMC 0.35 mu m CMOS process parameters. Based on the evaluation, the behavior of one of the circuits featuring better performance was also experimentally measured using the UVC-NIC 0520 integrated circuit.