All-optical precoder circuit for differential quadrature phase-shift keying (DQPSK) transmitter is designed and simulated employing micro-ring resonator as a fundamental technology. In DQPSK, the data symbol is encoded as the phase difference from one symbol period to the next instead of the absolute phase of the symbol. The precoder has been designed using 4:1 multiplexer (MUX) and clocked D flip flop realized with ring resonator based all-optical switch. The expected precoder operation is theoretically validated through numerical simulations at 266 Gbps. The MRR critical parameters, including radius and detuning, are optimized against performance metrics through numerical simulation. The selection of these parameters according to the determined specifications could provide feasible practical implementation of the scheme and its utilization for all-optical signal processing purposes.