I'm working on an oscillator design using an off the shelf integrated circuit-based oscillator.
I have made two large gnd planes in the PCB, the top layer as well as the bottom layer.
Is this a good practice esp. for making PCBs for applications like oscillators?
I have also added plenty of vias to connect the two layers.
I just wanted suggestions (if any) before I send the PCB for fabrication.
For RF boards usually there would be vias right at the edge of the board as Wolfgang says, because the electric field can be terminated toward it (probably requires a textbook for a better explanation!).
The chip you're using (LTC1799) doesn't have particularly fast edges or clock rate, so I think you'll be OK, but worth adding in vias.
If it helps, there's a project using that chip here: Building a Fast Edge Square Wave Generator
(the output was connected to buffers to sharpen up the edges for that project). As you can see, I did as Wolfgang refers to, with the top ground plane pulled back where it wasn't needed. The top plane is really useful for preventing the board from warping, but occasionally gets in the way. I have the tiniest 50 ohm trace because the rest of it wasn't 50 ohm characteristic impedance.
Yes, the vias along the edge of the PCB act as a wall for the electic field and the field remains confined to the board. It is called as SIW (Substrate Integrated Waveguide). However, considering that this is pretty low freq. (LTC1799 can go upto 33MHz only) so I'm have skipped things like 50 ohms line, matching and edge vias but I think It's better to add those vias as it will improve the performance.
I'm an RF engineer so I'm well aware about those rules 
But those rules are more critical above few 100's of MHz and GHz range, so I decided to skip it.
Another reason to not include the 50 ohm trace is my oscilloscope only has a High Z port. So designing a 50 ohms trace and using 50 ohms connector will anyway give a mismatch. Also, I tried assembling LTC1799 on a small perfboard and directly connected the probe at the output, it just worked fine.
Anyway, thanks for the inputs. I'll do slight changes in the design.
Yes, the vias along the edge of the PCB act as a wall for the electic field and the field remains confined to the board. It is called as SIW (Substrate Integrated Waveguide). However, considering that this is pretty low freq. (LTC1799 can go upto 33MHz only) so I'm have skipped things like 50 ohms line, matching and edge vias but I think It's better to add those vias as it will improve the performance.
I'm an RF engineer so I'm well aware about those rules But those rules are more critical above few 100's of MHz and GHz range, so I decided to skip it.
Another reason to not include the 50 ohm trace is my oscilloscope only has a High Z port. So designing a 50 ohms trace and using 50 ohms connector will anyway give a mismatch. Also, I tried assembling LTC1799 on a small perfboard and directly connected the probe at the output, it just worked fine.
Anyway, thanks for the inputs. I'll do slight changes in the design.
