Note 10 - Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Net operating loss carry forwards	$ 504	$ 18,205
Research and development tax credits	232	404
Capitalized research and development	13,026	0
Stock based compensation and other	3,878	3,694
Operating lease obligation	856	1,339
Total deferred tax assets	18,496	23,642
Less: Valuation allowance	(18,189)	(23,179)
Operating lease right-of-use assets	(307)	(463)
Net deferred tax assets	$ 0	$ 0