How to use an op-amp (that only uses ground and positive voltage to operate) to create a sawtooth/triangle wave generator?
You've specified your VCO output frequency range but didn't specify the triangle / sawtooth wave frequency. I'm guessing that you're using this to sweep the VCO so it will be operating at a much, much lower frequency. If that's the case then all the 300 - 400 MHz info in your question is irrelevant.

Figure 1. Square and triangle wave generation. (Don't use 741s. Use something modern.) Image source: Circuits Today.
In the case of the triangle wave you could use something like that of Figure 1 but instead of referencing R3 and R6 to battery negative you would generate a mid-supply reference and connect them to that.



simulate this circuit &ndash; Schematic created using CircuitLab
Figure 2. A mid-supply ground reference.
You'll see this solution used a lot in guitar effects pedals that run from a single 9 V battery but require AC swing about the &quot;zero&quot; reference internally.

Remember that op-amps don't have a GND pin. They only have a positive and negative supply so they don't care what your GND is as long as you give it adequate voltage between it's power pins and don't exceed the maximum input specifications.