Abstract: 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.

Abstract: Electronic devices are typically coupled together to operate as systems that require the communication of data between two or more devices. Many of these devices includes a communications circuit, such as receiver, transmitter, or transceiver for this purpose. A typical component in these communication circuits is the phase-lock loop, a circuit that in receiver circuits determines the timing of pulses in a received data signal and in transmitter circuits clocks the data out at a predetermined rate. One problem with phase-lock loops and thus the receiver and transmitter circuits that incorporate them is that they are generally tuned, or tailored, to operate at a certain frequency. This means that one cannot generally use a receiver or transmitter circuit having phase-lock loops tuned for one frequency to communicate at another frequency. The inability to communicate at other frequencies limits the usefulness of not only the receiver and transmitter circuits but also their electronic devices.

Abstract: A high speed data communication system includes a receiver to recover data and clock signals from communicated data. The receiver circuit has a dual phase lock loop (PLL) circuit. A fine loop of the PLL includes a phase detector providing a differential analog voltage output. Transconductance circuitry converts the differential analog voltage output to a low current analog output. The transconductance circuitry has a variable gain which is controlled by an automatic gain adjust circuit. A coarse loop of the PLL allows for fast frequency acquisition of an internal oscillator.

Abstract: A mixed signal integrated circuit is provided having analog and digital circuits coupled to receive respective analog and digital clocking signals. The analog circuit portion may involve switched capacitors which charge and discharge based on timing of the analog clocking signal. The critical sampling moments mandated by the analog clocking signal are purposefully delayed after a quiet time so that pre-existing, digitally induced noise does not impute error in the sampled or loaded voltages. A clocking generator is therefore presented which delays rising edges of the digital clocking signal from falling edges of the analog clocking signal. The amount of delay is chosen to ensure that asynchronously generated noise arising from the digital clocking signal does not substantially affect the critical sampled or loaded voltages. The digital circuit portion can therefore include a memory element having transitory bit lines and a sense amplifier coupled to receive voltages on those bit lines.

Abstract: A mixed signal integrated circuit is provided having analog and digital circuits coupled to receive respective analog and digital clocking signals. The analog circuit portion may involve switched capacitors which charge and discharge based on timing of the analog clocking signal. The critical sampling moments mandated by the analog clocking signal are purposefully delayed after a quiet time so that pre-existing, digitally induced noise does not impute error in the sampled or loaded voltages. A clocking generator is therefore presented which delays rising edges of the digital clocking signal from falling edges of the analog clocking signal. The amount of delay is chosen to ensure that asynchronously generated noise arising from the digital clocking signal does not substantially affect the critical sampled or loaded voltages. The digital circuit portion can therefore include a memory element having transitory bit lines and a sense amplifier coupled to receive voltages on those bit lines.

Abstract: A preamplifier provides an output signal which follows a varying resistance of a sensor of a condition or parameter. An example sensor is a magneto-resistive head employed in computer mass storage systems to read magnetic signals recorded on a magnetic tape or disk. The preamplifier uses a current-mode amplifier to increase its bandwidth and reduce signal distortion. A current source, used with the preamplifier or some other circuit, includes a low pass filter to reduce the effects of various noise sources.