A novel photonic approach to generate frequency-multiplied phase-coded microwave waveforms with large frequency tunability is proposed and experimentally demonstrated. By using a dual-drive Mach-Zehnder modulator, biased at specially designed bias point, and a single-port photodetector, phase-coded microwave waveforms at the doubled or tripled frequency of the applied microwave reference signal are generated, with a large frequency tunable range limited by the bandwidth of the dual-drive Mach-Zehnder modulator. The proposed technique is experimentally verified. Phase-coded microwave waveforms at the doubled frequency from 16 to 30 GHz and the tripled frequency from 21 to 30 GHz are generated. The pulse compression performance of the generated phase-coded microwave waveforms is also studied.