Abstract: The invention disclosed a method for digital image interpolation and sharpness enhancement, said method includes the following steps: 1) Inputting an image signal Xij to a first interpolation low pass filter FIR 1, said FIR 1 is a cubic interpolation filter having filter coefficient hi(n); 2) inputting an image signal Xij to at least one of second interpolation low pass filters FIR 2, said FIR 2 is an interpolation filter having filter coefficient hi′(n), wherein said FIR 2 has a cut-off frequency lower than that of said FIR 1; 3) making FIR 1 outputted via a band pass filter to obtain an image signal tij; 4) making FIR 2 outputted via a delay buffer to obtain an image signal tij′; 5) inputting said image signal tij and tij′ to a subtractor to get a differential signal tij−tij′; and 6) obtaining an output of image signal Yij by means of the following equation: Yij=tij+S·(tij−tij′), where S is a sharpness level control coefficient.

Abstract: The present invention provides an improved current mirror circuit. For example, in a voltage controlled oscillator of a phased-locked loop circuit, MOS device is used to replace a fixed resistor in the control circuit before the current mirror circuit for controlling the mirror currents of the related MOS devices in the phased-locked loop circuit, and for controlling the operating frequency of the phased-locked loop circuit.