Analog Devices,inc.

Other

Multigig, Inc.

Stephen Mark Beccue

Andrey Martchovsky

Anh Thu Pham

Robert Timothy Edwards

Anh D Pham

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.

Apparatus and methods for single phase spot circuits

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.

Apparatus and methods for phase linearization and interpolation in rotary traveling wave oscillators

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.

Apparatus and methods for multiphase oscillators

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.

Frequency temperature offset compensation

A plurality of inductance enhanced interweaved rotary traveling wave oscillators (RTWO) is disclosed. Portions of the transmission line conductors are increased in length and run in parallel. Because the currents in these portions travel in the same direction, the inductance of these inductors is increased. By controlling the length of the transmission line conductors in these areas compared to the lengths where the currents in the oscillators travel in opposite directions, the overall impedance of the oscillators can be increased. Increased impedance leads to lower power and lower phase noise for the oscillators. Additionally, the interweaved oscillators are phase-locked to each other.

Inductance enhanced rotary traveling wave oscillator circuit and method

A pulse width modulator based on a pair of rotary traveling wave oscillators. The first oscillator operates freely or as part of a phase-locked loop. The second oscillator operates at the same frequency as the first oscillator, but with a controllable phase offset from the first oscillator. The phase offset is set by an input voltage. A block takes the outputs of the first and second oscillators and combines them so that the output is a pulse whose width is the overlap of the oscillation signals from the first and second oscillators. The output pulse width is thus a function of the input voltage. When the pulse width modulator receives the input voltage from the output of a switching power supply, it can use the modulated pulse width to control the switching transistor of the power supply to maintain the output at a regulated voltage.

RTWO-based pulse width modulator

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.

Single pin read-write method and interface

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.

Low noise fractional divider using a multiphase oscillator

An inductance enhanced rotary traveling wave oscillator is disclosed. Portions of the transmission line conductors are increased in length and run in parallel. Because the currents in these portions travel in the same direction, the inductance of these inductors is increased. By controlling the length of the transmission line conductors in these areas compared to the lengths in which the currents travel in opposite directions, the overall impedance of the oscillator can be increased. Increased impedance leads to lower power, higher Q, and lower phase noise for the oscillator. Additionally, the folded nature of the transmission line conductors permits a longer length of transmission line conductors to be routed in a smaller area. The folded nature also permits placement of the devices to take into account their switching delays. A folded circular version of the oscillator is possible, leading to improved access to phase taps on the oscillator.

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.

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Thousand Oaks, CA, United States of America

Stephen Mark Beccue