In order to meet the application requirements of modern radar systems for linear frequency modulation (LFM) signals with high frequency and large time bandwidth product, a frequency 16-tupling LFM signal generation scheme using a cascaded double parallel Mach-Zehnder modulator and a cyclic secondary phase modulation loop structure is proposed. After theoretical analysis and simulation, it is verified that a LFM signal with a center frequency of 160 GHz, a bandwidth of 32 GHz, and a time bandwidth product (TBWP) of 310.3 can be generated when the radio frequency drive signal frequency is 10 GHz. In order to further improve the time bandwidth product of the generated signal, on the one hand, the parabolic drive signal is stretched or phase coded in the time domain to increase the time bandwidth of the generated signal. On the other hand, the parabolic drive signal is divided into multiple segments to increase the bandwidth of the generated signal. The results show that after the above processing, LFM signals with TBWP of 1272.05, 966.04, and 15346.75 can be generated, and the results are in good agreement with the theoretical analysis.