Abstract: Provided herein are apparatus and methods for single phase spot circuits. In certain implementations, a single phase spot circuit propagates a spot from input to output in response to a clock edge of a single phase clock signal. The single phase spot circuit holds the spot for about one clock cycle, thereby providing higher maximum operating frequency relative to multiphase spot circuits that hold a spot for about half of a clock cycle. Two or more single phase spot circuits can be electrically connected in a ring to operate as a spot divider. The single phase spot circuits can be used to advance a spot, represented using either a one or a zero, from one spot circuit to the next in response to a clock edge. In certain implementations, as the spot advances, a single phase spot circuit clears the spot from its input via a feedback element.

Abstract: Provided herein are apparatus and methods for single phase spot circuits. In certain implementations, a single phase spot circuit propagates a spot from input to output in response to a clock edge of a single phase clock signal. The single phase spot circuit holds the spot for about one clock cycle, thereby providing higher maximum operating frequency relative to multiphase spot circuits that hold a spot for about half of a clock cycle. Two or more single phase spot circuits can be electrically connected in a ring to operate as a spot divider. The single phase spot circuits can be used to advance a spot, represented using either a one or a zero, from one spot circuit to the next in response to a clock edge. In certain implementations, as the spot advances, a single phase spot circuit clears the spot from its input via a feedback element.

Abstract: Provided herein are apparatus and methods for single phase spot circuits. In certain implementations, a single phase spot circuit propagates a spot from input to output in response to a clock edge of a single phase clock signal. The single phase spot circuit holds the spot for about one clock cycle, thereby providing higher maximum operating frequency relative to multiphase spot circuits that hold a spot for about half of a clock cycle. Two or more single phase spot circuits can be electrically connected in a ring to operate as a spot divider. The single phase spot circuits can be used to advance a spot, represented using either a one or a zero, from one spot circuit to the next in response to a clock edge. In certain implementations, as the spot advances, a single phase spot circuit clears the spot from its input via a feedback element.

Abstract: Apparatus and methods for phase linearization and interpolation in rotary traveling wave oscillators (RTWOs) are provided. In certain configurations, an RTWO system includes a first elongated RTWO and a second elongated RTWO that are phase-locked to one another with a non-zero phase shift. The first and second elongated RTWOs each include two elongated sections of differential transmission line of high phase linearity. For example, such long and straight sections of the differential transmission lines can have uniform capacitance loading and avoid non-uniformities in length and/or thickness associated with poor phase linearity. The RTWO system further includes tap circuitry that receives clock signal phases from the elongated sections of the RTWOs. In certain implementations, the tap circuitry includes one or more interpolation circuits that interpolate received clock signal phases to increase the number of available phases. The RTWO system can include a large number of taps of high phase linearity.

Abstract: Apparatus and methods for multiphase oscillators are provided. In certain implementations, an oscillator system includes a first multiphase oscillator and a second multiphase oscillator that are phase and frequency-locked. Additionally, the first and second multiphase oscillators are phase-locked by an amount of phase shift that provides colocated clock signal phases of relatively wide angular distances, which can be used by the oscillators' amplification circuits. The first and/or second multiphase oscillators include one or more amplification circuits that operate using at least one clock signal phase generated by the first multiphase oscillator and using at least one clock signal phase generated by the second multiphase oscillator.

Abstract: Apparatus and methods for multiphase oscillators are provided. In certain implementations, an oscillator system includes a first multiphase oscillator and a second multiphase oscillator that are phase and frequency-locked. Additionally, the first and second multiphase oscillators are phase-locked by an amount of phase shift that provides colocated clock signal phases of relatively wide angular distances, which can be used by the oscillators' amplification circuits. The first and/or second multiphase oscillators include one or more amplification circuits that operate using at least one clock signal phase generated by the first multiphase oscillator and using at least one clock signal phase generated by the second multiphase oscillator.

Abstract: One embodiment relates to a method of compensating for crystal frequency variation over temperature. An example method includes obtaining an indication of temperature, computing a temperature compensation value based on the indication of temperature and a piecewise linear temperature compensation approximation, and compensating for a temperature offset in a crystal reference signal by adjusting a division ratio of a fractional divider in a phase-locked loop. The piecewise linear temperature compensation approximation can represent an approximation of frequency error in a crystal reference signal originating from a crystal over temperature. The piecewise linear temperature compensation approximation can be, for example, a linear approximation, a quadratic approximation, or a cubic approximation.

Abstract: One embodiment relates to a method of compensating for crystal frequency variation over temperature. An example method includes obtaining an indication of temperature, computing a temperature compensation value based on the indication of temperature and a piecewise linear temperature compensation approximation, and compensating for a temperature offset in a crystal reference signal by adjusting a division ratio of a fractional divider in a phase-locked loop. The piecewise linear temperature compensation approximation can represent an approximation of frequency error in a crystal reference signal originating from a crystal over temperature. The piecewise linear temperature compensation approximation can be, for example, a linear approximation, a quadratic approximation, or a cubic approximation.

Abstract: A method of communicating on a single serial line between two devices is disclosed. The method includes combining a data stream and a clock to form a three-voltage level stream such that the third voltage level records the transitions of the clock while the serial data is either high or low. Either the first or the second device can send a combined stream on the line. The method further includes, in some embodiments, the second device driving the same voltage levels as those transmitted by the first device and the first device sensing current on the single serial line to determine that the second device has received data from the first device.

Abstract: A frequency synthesis circuit is disclosed. The circuit includes a phase-locked loop and multi-phase oscillator such as a rotary traveling wave oscillator (RTWO). The oscillator provides a plurality of phases that are applied to a selection circuit. The selection circuit, in response to the output of a delta-sigma modulator, selects one of the phases of the multi-phase oscillator to minimize phase shift noise when the divider ratio in the loop changes, thereby eliminating a source of noise that contaminates the synthesized frequency. This permits the use of the frequency synthesis in applications requiring a high degree of spectral purity.

Abstract: A method of communicating on a single serial line between two devices is disclosed. The method includes combining a data stream and a clock to form a three-voltage level stream such that the third voltage level records the transitions of the clock while the serial data is either high or low. Either the first or the second device can send a combined stream on the line. The method further includes, in some embodiments, the second device driving the same voltage levels as those transmitted by the first device and the first device sensing current on the single serial line to determine that the second device has received data from the first device.

Abstract: A frequency synthesis circuit is disclosed. The circuit includes a phase-locked loop and multi-phase oscillator such as a rotary traveling wave oscillator (RTWO). The oscillator provides a plurality of phases that are applied to a selection circuit. The selection circuit, in response to the output of a delta-sigma modulator, selects one of the phases of the multi-phase oscillator to minimize phase shift noise when the divider ratio in the loop changes, thereby eliminating a source of noise that contaminates the synthesized frequency. This permits the use of the frequency synthesis in applications requiring a high degree of spectral purity.

Abstract: An oscillator is described. The oscillator includes segments of two-conductor transmission line being connected together by an odd number of connection means to form a closed loop. A plurality of current switches is connected to the conductors of the segments and a high impedance element, such as an inductor or transmission line, is connected to a conductor of at least one segment. The high impedance element sources current into the closed loop and the current switches sink current from one or the other of the conductors of the loop depending on the state of the switch. The switches cause a wave to be established and maintained on the loop and the wave changes the state of the switches as it oscillates. One embodiment of the switches employs npn transistors whose emitters are connected to a current source and another uses NMOS transistors.