[Show abstract][Hide abstract] ABSTRACT: Observability is mandatory for debugging purposes in all microelectronic systems. Mixed signal cores, in particular, require high observability in order to allow post production debug and to drive the design enhancements towards the real non-ideal behaviour monitored in individual modules. Controllability is also a major advantage in the design-for-debug process. This work presents a low cost controllability and observability methodology that is evaluated in terms of area cost and bandwidth capability for different operating conditions. The proposed methodology is used to add debugging capability to a DCDC, a charge pump, a LDO and a bandgap of a power management unit.