Abstract: Systems and methods are provided for hopping a digitally controlled oscillator (DCO) among a plurality of channels, wherein a gain of the DCO KDCO is a nonlinear function of frequency. A first normalized tuning word (NTW) corresponding to a first channel of the plurality of channels is generated. A first normalizing gain multiplier X is generated based on the nonlinear function of frequency, on an estimate of the nonlinear function of frequency, at a first frequency corresponding to the first channel. The first NTW is multiplied by the first X to obtain a first oscillator tuning word (OTW). The first OTW is input to the DCO to cause the DCO to hop to the first channel. A system for hopping among a plurality of channels at a plurality of respective frequencies comprises a phase-locked loop (PLL), a digitally controlled oscillator (DCO), a multiplexer, and an arithmetic module.

Abstract: A protection frame has a frame body and a supporting arm. The frame body is mounted around the portable device. The supporting arm is mounted pivotally on the frame body to allow the user to adjust the propping angle of the portable device. Therefore, the portable device can be used at different visual angles as desired.

Abstract: A protection frame has a frame body and a supporting arm. The frame body is mounted around the portable device. The supporting arm is mounted pivotally on the frame body to allow the user to adjust the propping angle of the portable device. Therefore, the portable device can be used at different visual angles as desired.

Abstract: A hinge is mounted in a sliding assembly for a portable device. The hinge has a hollow pintle, a first positioning ring, a second positioning ring and a resilient element. The positioning rings are mounted around the pintle and respectively have corresponding detents and protrusions to provide positioning function. The resilient element is mounted in the pintle and is mounted between the positioning rings to reduce the length of the hinge. When the second positioning ring is rotated, the second positioning ring also moves upward to lift the supporting panel of the sliding assembly and the cover of the portable device. Therefore, the cover is kept from bumping into the expanding parts of the portable device.

Abstract: A hinge is mounted in a portable device with two panels and has a flexible tube and a linking unit. The linking unit receives the flexible tube and is attached to the panels of the portable device. Since the flexible tube does not restrict the rotating angle, the panels can stay at any desired visual angle and are pivoted steplessly.