In this work, a reference spur reduction method for integer-N subsampling PLLs is presented. A dual-loop architecture is implemented with the loops operating at opposite phases of the oscillator. A feedback network with error amplifier is there to equate the control voltages of both loops. Finally, the control voltages are added and applied to the oscillator, which is quite clean compared to that of the individual loops, aiding in spur reduction. The design is implemented in CMOS 90 nm technology with a oscillator frequency of 1 GHz. Reference spurs are at offsets of 100 MHz and post-layout simulation results show that the highest spurs are at -45dBc.
This paper proposes a computationally efficient polyphase implementation of analytically designed 2D FIR filters, with circular frequency response. The design is achieved in the frequency domain and is based on 1D prototype filters with low-pass, zero-phase, maximally-flat characteristic. The 2D FIR filter transfer function results directly in factored form. The filter implementation method is described in a simpler case, namely for a smaller size of the filter kernel and of the input image. Using decimation with small factors and the block filtering approach, we obtain a very efficient filter implementation at system level, with a low computational complexity.
People of all races and ages are prone to having acne especially in their teens and twenties. In particular, acne represents a disorder of the hair follicles and oil sebaceous glands. Clogged sebaceous glans with sebum which they secrete to moist skin, leads to pimples and cysts creation. Different types of acne lesions detection are important in diagnosis and treatment. This is why two different computer aided acne detection methods has been developed and extensively tested as presented in this paper. They are classified and identified by their primary characteristics, namely method A based on a saturation component involving sinus hyperbolics function and method B is focusing on contrast enhancement. As a result of testing of their specific applicability it was documented that the proposed methods show to be robust and offer a successful analysis tool in differentiating and detecting acne and scars areas in the images taken under various environmental and clinical conditions. While method A with its saturation component approach appears be more suitable in cases of subjects whose back show higher concentration of acne indicators, method B which uses contrast enhancement, offers advantage in cases of face focused acne indicators that are usually not uniform in affected populations.
The classical stereophonic acoustic echo cancellation (SAEC) setup requires the estimation of four acoustic impulse responses using four adaptive filters. The widely linear (WL) model was used in the past to simplify the manipulation of the SAEC scenarios, and allows the use of a single adaptive filter working with fewer complex valued signals and coefficients, requiring the same overall arithmetic resources. This paper compares the performances of the recursive least-squares (RLS) algorithm combined with several line search methods (LSMs) working within the WL framework. Simulation results are shown in order to demonstrate the performances of the proposed methods, and numerical estimations are presented regarding arithmetic complexities, with respect to practical applications and possible future developments.
This paper investigates the use of State Space design approach for the implementation of a controller dedicated to a multiphase buck converter. This approach benefits from using, in control, all phase currents along with the output voltage. While the proposed solution is generally applicable, the numerical example herein considers a 5-phase buck converter from 12 V input to 1.2 V output, under 100 A load. Design of the control system is done in MATLAB® following a pole placement design strategy. This paper investigates the practical (implementation) limitations of the method.
