max 2620
Make a VCO in the GHz range, that easily covers 1GHz of bandwidth. Then mix its output with a constant LO and filter out the low-frequency mixing product.
For example:
VCO: 2GHz - 3GHz
LO: 2GHz
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After mixing and low-pass filtering you get 0-1GHz. All required components you can get at Mini-Circuits.
For example, for hobby use I've managed to cover from 70MHz to 310MHz in a single sweep. So for a 1GHz bandwidth, you would have at least 3-5 of this-kind oscillators.