Although a variety of CFOA-based biquads have been known in the literature, any CFOA-based circuit capable of realising universal biquad filters in all the four possible modes i.e. voltage-mode, current-mode, trans-admittance-mode and trans-impedance-mode, has not been reported in the literature so far. In this paper, a novel configuration has been presented, which realises all the five generic filter functions (namely, low-pass, band-pass, high-pass, notch and all-pass) from the same circuit in all the four possible modes, employing only four-Current feedback operational amplifiers (CFOA) along with two grounded-capacitors as desirable for Integrated Circuit implementation. The workability of the circuit has been confirmed by hardware implementation based on AD844 type CFOAs.
A new and fast motion-estimation algorithm based on partial block distortion using sorted significant features including bit-plane and mean is proposed. The proposed algorithm can obtain relatively accurate motion vectors with a reduced computational load. Simulation results show that the proposed method achieves its MSE performance very close to the full search method, while requiring only 6-8% of the computation needed by the full search. Furthermore, the performance of our method is better than other algorithms based on partial block distortion search.
A new tunable integrated transformer topology together with its tuning method is presented. The proposed tunable topology consists of a conventional tapped transformer and a coupled inductor. The phase shift between the input power into the primary winding and that into the coupled inductor was used to control the electrical characteristics such as maximum stable gain, input impedance and quality factor. The new tunable transformer achieved about 3dB higher maximum stable gain and 2.8 times higher quality factor compared to the conventional transformer.
The room-temperature operation of a GaN/AlN quantum well infrared photodetector (QWIP) using the intersubband transition (ISBT) in a GaN/AlN multiple quantum well (MQW) was demonstrated for the first time. The GaN/AlN QWIP was operated under DC biasing with a vertically conductive geometry to the MQW layer. A clear photoinduced response was observed for P polarized 1.47µm light irradiation. Dependencies of the photoresponse on the applied DC bias voltage, and the polarization and wavelength of incident light were evaluated for the GaN/AlN QWIP. The maximum responsivity was estimated to be 0.11mA/W for a DC bias of 15V at room temperature.