Abstract: A configuration for FPGA logic is provided to perform random access channel (RACH) preamble detection used in 3G mobile communications to identify individual rows of a Hadamard matrix using a Walsh Hadamard Transform (WHT). The configuration provides minimal add/subtract circuit blocks for the WHT by using stages, each stage containing a shift register connected to an add/subtract circuit. The shift register has outputs provided from a tap into its nth and n/2 elements, the outputs being connected to an add/subtract circuit, wherein n is the order of the Hadamard matrix. In a further embodiment parallel connected shift registers are used in each stage to increase operation speed.

Abstract: A circuit to generate Orthogonal Variable Spread Factor (OVSF) codes for CDMA systems. The circuit includes a shift register to determine the OVSF code k for a given spread factor SF, wherein k ranges between 0 and (SF?1). A memory cell register stores the leftmost bit of the code that is loaded into the first bit of the shift register. An XOR gate provides an input to the shift register after the first bit is loaded from the memory cell. An address Look Up Table (LUT), or state machine, is connected to the shift register to select a tap output from one of the shift register bits to provide a first input to the XOR gate. A secondary OVSF code register connects to a second input of the XOR gate to provide code bits from lower SF values making up the code from the current SF value.

Abstract: Microelectromechanical RF and microwave frequency power limiter and electrostatic protection devices for use in high-speed circuits are presented. The devices utilize an airbridge or a cantilever arm including a contact pad positioned operatively adjacent to an electrically conductive and substantially planar transmission line. When the power level in the transmission line exceeds a particular threshold, the airbridge or cantilever arm yields due to force between the contact pad and the transmission line, directing undesired power away from active devices. This characteristic can either serve as a method by which to limit the amount of power passing through the transmission line to a determined value or as a method by which to protect devices along the transmission line from damage due to large electrostatic bursts.

Abstract: Microelectromechanical RF and microwave frequency power limiter and electrostatic protection devices for use in high-speed circuits are presented. The devices utilize an airbridge or a cantilever arm including a contact pad positioned operatively adjacent to an electrically conductive and substantially planar transmission line. When the power level in the transmission line exceeds a particular threshold, the airbridge or cantilever arm yields due to force between the contact pad and the transmission line, directing undesired power away from active devices. This characteristic can either serve as a method by which to limit the amount of power passing through the transmission line to a determined value or as a method by which to protect devices along the transmission line from damage due to large electrostatic bursts.

Abstract: The present invention provides a flexible mechanical bridge over a microstrip on a substrate, which utilizes an electromagnetic field increase, as generated by temporary power surge to shunt harmful power away from a MMIC system. The invention includes a power limiter which includes an airbridge 11, preferably in the form of an electrically conductive strip with ground contacts 1 and 3 formed thereon. The ground contacts 1 and 2 are electrically connected, through via holes 5 and 7 respectively, to a metallization layer 15 formed on the bottom side of a substrate 9. The air bridge 11 is designed such that it traverses an electrically conductive microstrip 13 forming an air gap 16 between the air bridge 11 and the electrically conductive microstrip 13. When there is a power surge the air bridge 11, will flex to cause an electrical connection with the microstrip 13, thereby directing the unwanted signal through the ground contacts 1 and 3 and the via holes 5 and 7 to the metallization layer 15.