The heart of this project is AD9834 – Direct Digital Synthesizer chip, which is capable to generate sine and triangular wave upto 37.5MHz. The inbuilt comparator in the DDS chip can be used to generate square wave signal from the sine wave. The chip is controlled by a PIC microcontroller using a serial communication interface (SPI). A programmable gain amplifier (LMH6505), where gain is set by a control voltage from a digital potential divider and a buffer amplifier, amplify the output of DDS to a required level. A DC shift of output signal is also possible.
The PIC microcontroller provides the necessary user interface with LCD display, and keypad. Using this one can set frequency, output level, dc offset etc. easily.