摘要:
The low maintenance speed bump is an elongated, rigid, solid body having an arcuate top surface and a flat base, angled grooves defined in the top surface, and a reflective material disposed within the grooves. The reflective material is disposed lower than the top surface of the speed bump to prevent contact between vehicles passing over the speed bump and the reflective material. In this manner, the reflective material is protected from damage by vehicle tires and the life of the reflective material is extended. Further, the angled grooves provide greater visibility of the reflective material to drivers approaching the speed bump.
摘要:
Described are fast synchronous counters with reduced combinatorial logic. In one embodiment, a four-bit shift register is configured in a ring and preset with a data pattern (e.g., 1000). The register is then rapidly shifted into any of four unique states. Combinatorial logic connected to the shift register converts the four unique states into a two-bit binary signal representative of the four states. In the general case, counters in accordance with this embodiment represent N-bit binary numbers using 2N synchronous storage elements. Two or more counters can be combined to produce larger synchronous counters. An up/down counter in accordance with yet another embodiment is connected to a multi-path delay line to create a variable delay circuit. The switching speed of the delay circuit is independent of the number of delay settings. Also advantageous, the delay circuit scales linearly, in terms of power consumption and area, with changes in delay granularity.
摘要:
A high speed phase detector circuit operating at a clock speed equal to one-half an input data rate (i.e. a half-rate clock) provides phase information and transition information from incoming serial data. The high speed phase detector circuit samples the incoming serial data on both the rising edge and falling edge of the half-rate clock to provide equivalent full high speed data rate sampling. The high speed phase detector circuit generates a delay between the phase information and the transition information. The phase information is produced in a first bit period and the transition information is produced in a second bit period relative to the first bit period.
摘要:
A data density independent clock and data recovery system includes a lock phase adjust charge pump operably coupled to receive phase information and transition information from a phase detector and to produce a current signal, responsive to the phase information and transition information, to a loop filter that converts the current signal to a control voltage signal operably coupled to a voltage controlled oscillator that produces a clock signal to the phase detector based on the control voltage signal. The lock phase adjust charge pump includes a phase charge pump, a transition charge pump, a programmable DC bias current sink, and two programmable offset bias current sinks. The transition charge pump includes a programmable transition current sink. The control logic operates under external control to adjust the currents conducted by the transition charge pump, the programmable DC bias current sink, and the two programmable offset bias current sinks.
摘要:
In many electronic systems, it is common to communicate data from a transmitter in one device to a receiver in another. Accurate communications requires use of several matched clock signals. Mismatches in these clock signals cause transmitters to add “jitter” to transmitted data or receivers to be more intolerant of jitter in received signals, increasing the chances of mis-interpreting the data. Accordingly, the inventors devised an exemplary clock-distribution method which entails generating a base set of matched clock signals, deriving at least two separate sets of matched clock signals from the base set, and distributing one of the sets of clock signals to a set of matched components in a circuit and the other set of matched clock signals to a different set of components in the same circuit. The clock signals driving the matched components are isolated from mismatched aspects of the other components, and thus exhibit better matching. This method improves the accuracy of high-speed receivers, transmitters, transceivers, and other communications circuits that use it.
摘要:
A method and apparatus for combining an alternating current (AC) coupling technique with a low frequency restoration technique to provide AC coupling with low frequency restoration of the attenuated low frequency content. The low frequency restoration circuit operates to extract low frequency information prior to being high-pass filtered by the AC coupling circuit. The low frequency restoration circuit then buffers the low frequency information through a low frequency restoration amplifier, applies a programmable common mode voltage to the buffered, low frequency information, and then restores the buffered, common mode adjusted, low frequency information to the output of the AC coupling circuit.
摘要:
Electronic devices are typically coupled together to operate as systems that require the communication of data from one device to another. Many such devices include a ring oscillator, a circuit that generates one or more oscillating signals using a series of interconnected delay circuits. One problem with conventional ring oscillators concerns differences in the signal paths between the delay circuits. Accordingly, the present inventors devised several oscillators having unique layouts, which reduce differences in the signal paths between delay circuits. One exemplary oscillator includes a sequence of delay circuits having input-output connections between at least two pairs of non-adjacent delay circuits. Another exemplary oscillator provides two groups of delay circuits with a bus between the two groups, intercoupling the circuits. And, another exemplary oscillator arranges three or more delay circuits to form a closed loop. Applications for these oscillators include not only receivers, transmitters, and transceivers, but also programmable integrated circuits, electronic devices, and systems.
摘要:
Described are fast synchronous counters with reduced combinatorial logic. In one embodiment, a four-bit shift register is configured in a ring and preset with a data pattern (e.g., 1000). The register is then rapidly shifted into any of four unique states. Combinatorial logic connected to the shift register converts the four unique states into a two-bit binary signal representative of the four states. In the general case, counters in accordance with this embodiment represent N-bit binary numbers using 2N synchronous storage elements. Two or more counters can be combined to produce larger synchronous counters. An up/down counter in accordance with yet another embodiment is connected to a multi-path delay line to create a variable delay circuit. The switching speed of the delay circuit is independent of the number of delay settings. Also advantageous, the delay circuit scales linearly, in terms of power consumption and area, with changes in delay granularity.
摘要:
Described are fast synchronous counters with reduced combinatorial logic. In one embodiment, a four-bit shift register is configured in a ring and preset with a data pattern (e.g., 1000). The register is then rapidly shifted into any of four unique states. Combinatorial logic connected to the shift register converts the four unique states into a two-bit binary signal representative of the four states. In the general case, counters in accordance with this embodiment represent N-bit binary numbers using 2N synchronous storage elements. Two or more counters can be combined to produce larger synchronous counters. An up/down counter in accordance with yet another embodiment is connected to a multi-path delay line to create a variable delay circuit. The switching speed of the delay circuit is independent of the number of delay settings. Also advantageous, the delay circuit scales linearly, in terms of power consumption and area, with changes in delay granularity.
摘要:
A method and circuit for determining variation between an input clock signal (CLK0) and a reference clock signal (REFCLK) is provided. A plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be generated from a single input clock signal (CLK0). The plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be sampled at successive periodic intervals occurring relative to the reference clock signal (REFCLK). For each of the time shifted input clock signals (CLK0, CLK1, . . . , CLK09), a sampled value for a succeeding and a preceding periodic interval can be compared to determine whether there is a variation between an input clock signal (CLK0) and a reference clock signal (REFCLK).