This paper proposes signal generator (BIST/BOST) algorithms and architectures for mixed-signal IC testing input. They can provide rectangular waveforms approximated to single-tone and/or two-tone signals with harmonics/IMD suppression. Their circuit consists of digital circuit, a 1-bit DA converter with an analog filter. Proposed method is simple for implementation with modest performance, compared to a wide dynamic range delta-sigma DAC [1, 2] and other methods [3-5].