This paper proposes a new critical conduction mode (CRM) DC-DC topology based on quadratic high gain boost converter (QHGBC). Quadratic converter is a high gain topology, which has the drawbacks of high conduction loss in the input diodes and high switching loss in the main switch. A direct implementation of CRM scheme for QHGBC does not result in soft switching, as the switch voltage is clamped to the intermediate level by the input diodes. Adding a small auxiliary inductor in series with one of the input diode as proposed here, together with suitable design considerations for output side inductor and resonant time, results in complete zero voltage switching (ZVS) for both the MOSFETs. Additionally, input diode transitions undergo zero current switching (ZCS) without reverse recovery, which reduces the overall electromagnetic interference (EMI) issues. The main advantage of CRM approach for QHGBC is that the input current ripple can be very small and only the output side inductor which carries significantly lower current needs to have a high ripple. PLECS based extensive simulations and results obtained from hardware prototype corresponding to the DC-DC stage of a PV microinverter validate the performance of the proposed converter. A peak efficiency of 96.4%, and efficiencies above 94.7% under all operating conditions are achieved.