The ICL8038 waveform generator was an Integrated circuit by Intersil designed to generate accurate sine, square & triangular waveforms based on bipolar monolithic technology involving Schottky barrier diodes. Triangular waves were produced by charging and discharging a capacitor with constant currents. The triangular waves were converted to sine waves involving a non-linear network of transistors and thin-film resistors.
The output frequency was set by resistors or capacitors and covered a range from 0.001 Hz to more than 300 kHz. An external control voltage would accomplish frequency sweeping or frequency modulation. The temperature drift could be optimized to less than 250ppm/°C by combining it with a PLL.
Maxim designed a copy of the ICL8038 and marketed it as the MAX038. Both devices have since been discontinued.