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CMOS broad-band compact high-linearity binary phase-shift keying (BPSK) and IQ modulators are proposed and analyzed in this paper. The modulators are constructed utilizing a modified reflection-type topology with the transmission lines implemented on the thick SiO2 layer to avoid the lossy silicon substrate. The monolithic microwave integrated circuit (MMIC) chips were fabricated using standard bulk 0.13-μm MS/RF CMOS process and demonstrated an ultracompact layout with more than 80% chip size reduction. The broadside couplers and 180° hybrid for the modulators in the CMOS process are broad-band designs with low phase/amplitude errors. The dc offset and imbalance for the proposed topology are investigated and compared with the conventional reflection-type modulators. The measured dc offset was improved by more than 10 dB. Both BPSK and IQ modulators feature a conversion loss of 13 dB, a modulation bandwidth of wider than 1 GHz, and second- and third-order spur suppressions of better than -30 dBc. The IQ modulator shows good sideband suppression with high local-oscillator suppression from 20 to 40 GHz. The modulators are also evaluated with a digital modulation signal and demonstrate excellent modulator quality and adjacent channel power ratio.