I'm using an Charge Pump Inverter,MAX899R in free run mode with switching frequency of 500kHz like in the circuit attached. The problem is that I'm seeing a lot of switching noise in the output, much more than i expected as it is visible in the figure attached. Moreover the noise has a frequency of 1MHz, and not 500 KHz, is this normal ? How could i fix the problem ?
Update
After a suggestion of AndyAka, I checked the ground and it has the noise I'm seeing in the output, I read it would improve to use a ferrite bead after GND and after VCC but no improvements. I'm adding 3 more pictures with the noise at the ground(fig1), noise in the VCC with osciloscoppe earth probe closer to C11(fig2) and the noise in VCC with earth probe closer to C20.
Best Answer
Background: -
The basic problem here is your scope is picking up a signal in the loop formed with its ground connection. You need to use a better probe or a differential measurement. Here's apicture from TI that explains the problem: -
The picture was taken from Understanding, Measuring, and Reducing Output Voltage Ripple by Texas Instruments and covers the issue of good scope probing techniques.