This paper presents a new standing-wave clock distribution scheme utilizing an inductor loading technique. The scheme can distribute multi-ten GHz uniform-phase/amplitude global clocks over a whole chip. By loading an adequate inductor, the grid pitch can be made finer than that for the conventional standing-wave technique, and clock frequency can be designed to be independent of the grid pitch. We designed a 20GHz 6 x 6 grid clock distribution network using a 0.18µm CMOS technology. For all 36 clocks, low skew less than 1.3% of the clock period and low amplitude deviation of 2% were obtained from circuit simulation.
The stability of adiabatic stepwise charging reversible logic is discussed from the viewpoint of coupled oscillators. For adiabatic logic with asymmetric tank capacitors, we derive a matrix that connects the initial voltage with the voltage change after the charge-recycle process. This matrix is the same as the mechanical oscillator matrix of a string with equally spaced beads having different mass. From the theory of normal modes in coupled oscillators, it is proved that the eigenvalue of the matrix connecting the initial voltage with the final one is less than 1, which shows that a step waveform is spontaneously generated after many charge-recycle processes.
This paper presents a combined DWT and LSB based biometric watermarking algorithm that securely embeds a face template in a fingerprint image. The proposed algorithm is robust to geometric and frequency attacks and protects the integrity of both the face template and the fingerprint image. Experimental results performed on a database of 750 face and 750 fingerprint images show that the algorithm has the advantages of both the existing DWT and LSB based algorithms. A multimodal biometric algorithm is used as a metric to evaluate the combined performance of both face and fingerprint recognition.
The authors investigate the feasibility of mechanical beam scan by moving dielectric blocks in the feed waveguide of single-layer slotted waveguide arrays. A model using two phase shifters of polycarbonate (εr =2.8) is designed and fabricated with three radiating apertures at 12GHz band. 90-degree phase difference is obtained between the adjacent windows to give 11-degree shift of the main beam. Another phase shifter of alumina (εr =9.8) gives larger phase shift of 133 degrees corresponding to 15-degree beam tilt.