Anritsu Company

Micro Lambda Wireless, Inc.

Oleksandr Chenakin

Nikolay Shtin

Suresh P Ojha

Frequency synthesizers having reduced phase noise and a small step size. One example can provide frequency synthesizers having low phase noise by eliminating dividers in a feedback path and instead employing frequency converters, such as mixers. Step size can be further reduced by providing frequency converters in a reference signal feedforward path. Acquisition time can be decreased by employing a fast-acquisition phase-locked loop that is switched out after acquisition in favor of a low phase-noise phase-locked loop. Another example can reduce phase noise by employing a YIG oscillator. To improve acquisition time, a first, faster phase-locked loop can be used to lock to a signal before switching to a second, slower phase-locked loop that includes the YIG oscillator. Another example can provide low noise by including phase-locked loops that operate in a frequency range having low thermal noise while a frequency of an output signal varies over a wide range.

Frequency synthesizers having low phase noise

Circuits, methods, and apparatus that can provide oscillator circuits that have reduced phase noise. An example can provide a yttrium-iron-garnet oscillator in a loop with a loop amplifier and a phase-shift circuit. The yttrium-iron-garnet oscillator can act as a resonator. Quadrature outputs of the yttrium-iron-garnet oscillator can drive a phase detector that can provide a control signal to the phase-shift circuit. The phase-shift circuit can then reduce or cancel phase noise in the loop, thereby enabling the loop to provide a reference signal having reduced phase noise.

Oscillator with phase-noise cancellation

Circuits, methods, and apparatus that can reduce or suppress phase noise in a frequency synthesizer. A phase-noise-suppression system can detect phase noise in an input signal, amplify the detected phase noise, subtract the detected phase noise from the input signal, and provide an output signal having reduced phase noise.

Phase noise suppression for reference oscillator

An apparatus and method for building and operating of a YIG-based filter-attenuator module with closed-loop control. The module combines both signal filtering and amplitude control functions by utilizing an yttrium-iron-garnet (YIG) resonator. A technique for a closed-loop calibration and control also disclosed. This apparatus and method provides a cost effective harmonic rejection/amplitude control solution for microwave test-and-measurement instruments such as signal generators and spectrum analyzers.

YIG-based closed loop signal filtering and amplitude control

A dual-resonator YIG oscillator with a main YIG resonator and a stabilizing YIG resonator both suspended in a common magnetic field. The main YIG resonator takes on the high-Q factor aspects of the oscillator, while the stabilizing YIG resonator helps stabilize the operation of the main YIG resonator, and also allows the main YIG resonator operate at higher magnetic field strengths, achieving higher frequency operation. The stabilizing YIG resonator also enables the oscillator's active device to operate in a more linear, lower phase noise, regime. As compared to conventional YIG oscillators, the disclosed dual resonator YIG oscillator provides significant performance improvements, such as higher frequency operation, lower power consumption, higher tuning speed, and lower phase noise.

System and method for reducing phase noise in high frequency YIG oscillators

An improved noise-corrected phase-locked loop frequency synthesizer configured to reduce noise, such as phase noise and spurious signals, without the use of switching circuits. The synthesizer uses a phase shifter device configured to accept a noise containing frequency signal from a voltage controlled oscillator (VCO) circuit, such as an integer-N single loop PLL synthesizer, as well as noise reducing control signals from a noise detecting sensor or circuit, and output a noise reduced VCO frequency signal. In some embodiments, the noise reducing sensor may be formed from a second, lower noise, phase locked loop circuit. The frequency synthesizer circuit, noise detecting sensor, and the phase shifter device are configured to all run continuously, with the noise reducing sensor and frequency shifter continually acting to reduce noise, produced by higher noise integer-N PLL frequency synthesizer.

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Morgan Hill, CA, United States of America

Oleksandr Chenakin