We have proposed an 8PSK modulator based on three microring modulators (MRM). The design consists of three MRMs, each with a radius of 11.1μm. Of these three, two MRMs are connected in parallel and they together generate a QPSK (Quadrature phase shift keying) signal. While at the output port of the QPSK, a third MRM is connected in series works as an angle modulator, which is basically a 45o phase shift modulator; i.e., the output of the MRM varies by 45o depending on the bit pattern fed to it, ’0’or ’1’ respectively. In the result section, we have simulated and shown the performance of the proposed 2.5 GBaud 8PSK modulator after transmitting the modulated signal through various lengths of optical fiber. The bit error rate (BER) vs. optical signal to noise ratio (OSNR) curve shows that, 10−3BER has been achieved at 13.5dB OSNR.