This paper presents a novel continuous-phase phase-shift-keying (CP-PSK) modulation scheme and a low-power quadrature modulation architecture. In the proposed modulation scheme, phase-shift occurs in a smooth, continuous manner so that it can be implemented using an indirectly modulated frequency synthesizer. In the proposed transmitter architecture, low-power and low-complexity are achieved by employing two indirectly modulated synthesizers for the I and Q paths, thereby eliminating the need for mixers and digital-to-analog converters (DACs). Simulation results show that the bit error rate (BER) and the spectral efficiency of the proposed methods are close to those of ideal PSK modulation schemes.