Keysight Technologies 33522B Function Generator, 1μHz Min, 30MHz Max, FM Modulation, Variable Sweep, Series: 33500B, Digital Frequency: Yes, Minimum Frequency Range (Sinewave): 1µHz, Minimum Frequency Range (Square, Pulse and Arbitrary Waveform): 1 μHz, Maximum Frequency Range (Triangle/Saw): 20kHz.