In this paper, we present a high performance V-band quadruple sub-harmonic mixer monolithic circuit which is designed and fabricated for the millimeter wave down converter applications. While the typical sub-harmonic mixer use a half of fundamental frequency, we adopt a quarter of the fundamental frequency. The proposed circuit is based on typical sub-harmonic mixer with anti-parallel diode pair (APDP). Upon the typical mixer design, additional stubs are placed with the modification of original stub length. The stubs, 0.1 mum pseudomorphic high electron mobility transistors (PHEMTs) and other components are appropriately positioned to each port for maximizing quarter frequencies. Maximum conversion gain of 0.8 dB at a LO frequency of 14.5 GHz and at a RF frequency of 60.4 GHz is measured. Both LO-to-RF and LO-to-IF isolations are higher than 40 dB. The achieved result of conversion gain and isolation characteristic is one of the best performances reported among the quadruple sub-harmonic mixer operating in the V-band millimeter wave frequency. (C) 2003 Elsevier B.V. All rights reserved.