Development of Digital Variable Frequency Triangle Signal Generator Using Cygnal C8051F005 SoC

摘要

A circuit for generating triangle waveform with variable, digitally controlled frequency has been developed. The circuit utilizes a Cygnal C8051F005 System-on-a-Chip (SoC) for controlling the output frequency. Two 12-bit Digital to Analog Converters (DACs) included in the SoC feeds a voltage to a frequency converter to generate symmetrical bipolar triangle signal using four op-amps, which is an improved version of commonly found voltage controlled oscillator circuit. With one DAC, the frequency can be swept from 7 Hz to 3000 Hz while the amplitude remains constant. The second DAC is used to fine tune the frequency. The circuit also outputs synchronous square wave for frequency measurement by the SoC. The circuit was applied for testing or characterizing electronic devices or samples with fully digital control input from the user.