High Frequency Function Generator Using MAX038

Function generator ranging from 0.1 Hz to 20 MHz can be easily built using MAX038 integrated circuit chip. Here is the most simple implementation of high frequency sine wave generator, and you can easily modify it to generate square wave, or triangle waveform. Here is the schematic diagram of the circuit:

In the schematic diagram, you can see A0 (pin 3) and  A1(pin 4) inputs are hardwired to low and high voltage level, and this setting makes the chip produce sine waveform. We can modify this by programming them according to the table below:

• A0  A1                     WAVEFORM
• X     1                         Sine wave, X=don’t care
• 0     0                         Square wave
• 1      0                        Triangle wave

Another interesting feature of this integrated circuit chip is that the frequency is current-controlled, by controlling the current input at pin 10. This feature give flexible way to control the frequency. You can program the current from a DAC to make a digital interface, or you can even control it using the output of a phase error detector to make a PLL oscillator. If you use a phase error detector, you can use a crystal oscillator clock  and the MAX038 sync output (pin 14) as the inputs of the phase error detector, and you’ll get a very high pecission since the output of this function generator will be phase-locked with the crystal reference clock.