Current Measurement Transducer Based on CurrenttoVoltagetoFrequency Converting Ring Oscillator with Cascade Bias Circuit We propose a ring oscillator (RO) based currenttovoltagetofrequency (Ixe2x80x93Vxe2x80x93F) converting current transducer with a cascade bias circuit. The Ixe2x80x93Vxe2x80x93F converting scheme guarantees highly stable biasing against RO, with a railtorail output operation. This device was fabricated using National NanoFab Center (NNFC) 180 nm complementary metaloxidesemiconductor (CMOS) technology, which achieves a current resolution of 1 nA in a measurement range up to 200 nA. A noise floor of 11.8 pAxe2x88x9aHz, maximum differential nonlinearity (DNL) of 0.15 in 1 nA steps, and railtorail output with a 1.8 V power supply is achieved. The proposed transducer can be effectively applied to biosensing devices requiring a compact area and low power consumption with a low current output. The fabricated structure can be applied to monolithicthreedimensional integration with a biosensing device.

A DifferentialRingOscillator with up to 35 dBcHz Phase Noise Improving Amplitude Feedback Loop for Ultra Low Power Systems This work presents a novel idea to dynamically control a differential ring oscillators biasing in order to improve the phase noise performance in the ultra low power domain. This proposed feedback system can be flexibly applied on any type of fullydifferential ring oscillator with a tail current source. The following paper covers theoretical and simulative considerations to prove the feasibility of this idea. Finally measurements of a 180 nm standard CMOS integrated prototype system depict the implementability of this idea. A phase noise improvement of up to 35 dBcHz can be observed with an active control loop. Moreover, the tuning range of the implemented ring oscillator is extended by 434% in contrast to fixed bias operation. These values are measured at a minimum oscillation power consumption of 55 pWHz.