The contribution is focused on robust design and analysis of continuous-time controllers for SISO systems without and with time delays. Controllers are obtained via solutions of diophantine equations in the ring of proper and stable rational functions by Youla-Kuèera parameterization. Uncertainty is studied through the infinity norm. A scalar parameter was proposed as a tuning knob for minimization of the sensitivity function and uncertainty conditions. Both, feedback a feedback and feedforward structures of the controlled system are considered. Disturbance rejection and attenuation can be also easily solved by the proposed methodology.