Silicon Storage Technology, Inc.

G-plus, Inc.

Microchip Technology Inc.

Yi-Cheng Wu

Zhiwei A Xu

Mau-Chung Frank Chang

Heng-Yu Jian

Charles Chien

A phase lock loop includes a quantization circuit that generators an out of phase noise cancellation signal from an error in a delta-sigma modulator and applies the noise cancellation signal to the charge pump. The quantization circuit includes a digital-to-analog differentiator. The digital-to-analog differentiator may be, for example, a single-bit first-order digital-to-analog differentiator, a single-bit second-order digital-to-analog differentiator, or a full M-bit binary-weighted digital to analog differentiator.

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A local oscillator (LO) buffer circuit comprises first and second LO buffers arranged in a cross coupled configuration. The first LO buffer generates in-phase output signals in response to in-phase input signals, and quadrature output signals from the second LO buffer. The second LO buffer generates the quadrature output signals in response to quadrature input signals and the in-phase output signals. The LO buffers may include inductive loads. The LO buffers may include MOS transistors or bipolar junction transistors.

Cross coupled high frequency buffer

A phase lock loop (PLL) includes a calibration loop for calibrating a tank circuit for capacitance variation through process variations of manufacturing an integrated circuit including the PLL. A capacitance profile for setting the frequency of the PLL at a process comer is stored. At power up, or after an idle time, a calibration is performed at two frequencies. The capacitances of operating the phase lock loop at the two frequencies are determined and stored. During a frequency change, the capacitance of operating the PLL is determined from the capacitance profile and stored capacitances. The capacitance of the PLL is presumed to change linearly with frequency and the two stored capacitances are used to determine a difference capacitance at the selected frequency by linear interpolating between the two stored capacitances, which is added to the capacitance in the capacitance profile at the selected frequency to generate an operating capacitance.

Method and system for calibration of a tank circuit in a phase lock loop

A system or method for controlling a voltage controlled oscillator (VCO) or LO buffer includes an amplitude detector for detecting an amplitude value at a node corresponding to the at least one output line. A comparator compares the detected amplitude value with a predetermined amplitude value, and outputs a first digital value when the detected amplitude value is greater than the predetermined amplitude value, and a second digital value when the detected amplitude value is less than the predetermined amplitude value. An accumulator accumulates outputs of the comparator so as to provide an accumulated digital amplitude value. A digital-to-analog converter converts the accumulated digital amplitude value to an accumulated analog amplitude value. The analog accumulated amplitude value is provided as an updated bias control signal to the bias transistor of the VCO or LO buffer.

Digital control loop to improve phase noise performance and RX/TX linearity

An active inductor circuit includes a primary and a secondary coil and a drive circuit monolithically integrated on a common substrate to provide high-Q inductors. Each inductor circuit comprises a primary coil which carries a first current that varies with an RF input signal, and a secondary coil which carries a second current that varies with the RF input; an on-chip current source provides the second current. The inductor circuit is arranged such that there is a fixed phase difference of approximately 90&deg; between the first and second currents, and such that the magnetic field induced by the second current compensates for energy that would otherwise be dissipated by the primary coil. When the second current is properly selected, the inductor circuit's input impedance is made purely imaginary, such that the circuit emulates an ideal inductor at a particular frequency.

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Los Angeles, CA, United States of America

Yi-Cheng Wu