Waveforms: Function generators generally produce sine wave, square wave, pulse, triangular and sawtooth or ramp waveforms. It is worth checking the specifications of these individual waveforms.
- Sine wave distortion: Analogue function generators create a sine wave from the triangular waveform using a pair of back to back diodes to shape the waveform. Although this produces a good representation of a sine wave, the distortion levels will be higher than sine waves produced by other means. Accordingly the function generator specification for sine wave distortion needs to be checked if this may be an issue. Typical levels may be < 2%
- Triangular wave linearity: There will be some departure from a straight line on the triangular wave. Typically linearity is better than 99% between levels of 10 and 90% of the waveform amplitude.
- Square wave rise & fall times: Another important function generator specification can be the square wave edge rise and fall times. This can be an issue when driving some logic chips. Chips that are synchronous and use a clock may require an edge of a certain speed. Typically a function generator may provide a rise time of 100ns between 10 and 90% of the waveform. The fall time may also be of the same order as well, although possibly different to the rise time