Linear Technology Corporation

Other

John Perry Myers

Joseph Adut

Petrus Martinus Stroet

Franklin O Chain

A method and system of compensating for distortion in a baseband in-phase (I) and a corresponding baseband quadrature (Q) signal. The circuit includes an in-phase I attenuator configured to attenuate the baseband in-phase I signal and an in-phase Q attenuator configured to attenuate the baseband Q signal. There are one or more circuits that are configured to receive the attenuated in-phase I signal and the attenuated baseband Q signal. Each circuit performs a different calculation based on predetermined equations configured to determine the IM2, HD2@0&#xb0;, HD2@90&#xb0;, IM3@0&#xb0;, IM3@90&#xb0;, HD3@0&#xb0;, and HD3@90&#xb0;. The distortion compensation circuit is configured to use the result of at least one of the calculation circuits to generate I and Q distortion compensation signals.

Distortion compensation circuit

A method and system of compensating for phase error. A phase error compensation circuit is configured to generate a phase-corrected quadrature Q output signal and a corresponding phase-corrected in-phase I output signal, the circuit includes a first transconductance circuit configured to convert a voltage signal related to an I input voltage signal to an I current signal. A second transconductance circuit is configured to convert a voltage signal related to a Q input signal to a Q current signal. A first multiplier circuit is configured to multiply the Q current signal times a Q scaling constant. A second multiplier circuit is configured to multiply the I current signal times an I scaling constant. An I summer sums the I current signal with the scaled Q signal. A Q summer sums the Q current signal with the scaled I signal.

Phase error compensation circuit

A differential amplifier may, when connected to a positive or negative supply voltage and to a ground voltage, provide a differential pair of outputs signals at a differential output that are an amplification of a differential pair of input signals at a differential input. A differential input stage may receive the differential pair of input signals from the differential input and may include a first transistor associated with one of the input signals and a second transistor associated with the other input signal. A differential output stage may generate the differential pair of output signals at the differential output and may include a third transistor associated with one of the output signals and a fourth transistor associated with the other output signal. The first, second, third, and fourth transistors may be all P type or all N type. The differential pair of output signals may have a common mode that is: near the ground voltage when the first, second, third, and fourth transistors are all N type and the supply voltage is positive with respect to the ground voltage; near the supply voltage when the first, second, third, and fourth transistors are all P type and the supply voltage is positive with respect to the ground voltage; near the ground voltage when the first, second, third, and fourth transistors are all P type and the supply voltage is negative with respect to the ground voltage; or near the supply voltage when the first, second, third, and fourth transistors are all N type and the supply voltage is negative with respect to the ground voltage.

Level-shifting amplifier

A technique for cancelling out target IM2 components in a wireless receiver's mixer output is disclosed. A differential RF signal and a differential local oscillator (LO) signal are mixed by a mixer to demodulate the RF signal. A first common node signal is generated between a first resistor and a second resistor coupled across the mixer's differential output terminals. A second common node signal is generated between a third resistor and a fourth resistor coupled across the differential output terminals, where a capacitor is coupled between the second common node and a power supply terminal. The second common node signal provides a stable reference signal for IM2 components above a certain frequency. The two common node signals are subtracted to create a difference signal. The difference signal is scaled by a scaling factor obtained during calibration. The scaled difference signal is coupled to the mixer output to offset IM2 distortion.

Second order intermodulation canceller

A mixer in an RF demodulator includes a transconductance amplifier that converts an RF input voltage (Vin), applied to the base of a first bipolar transistor, to a first output current. The first output current contains third order intermodulation (IM3) products. An IM3 canceller is connected in parallel with the transconductance amplifier. The base of a second bipolar transistor in the IM3 canceller is coupled to the DC component of Vin, and the AC component of Vin is coupled to the emitter of the second bipolar transistor, such that the currents though the first bipolar transistor and the currents through the second bipolar transistor change oppositely. The collectors of the transistors are coupled together. The values of components in the IM3 canceller are set so that the current generated by the IM3 canceller substantially cancels IM3 distortion in the first current or other current generated in a demodulator of Vin.

Third order intermodulation cancellation for RF transconductors

A power measurement circuit and method are described. The circuit comprises: a transconductance rectifier arrangement including an input and configured to receive a periodically varying input voltage signal having an approximate 50% duty cycle; and an averaging filter for producing a time averaged DC output signal proportional to the mean square of the voltage at the input of the transconductance rectifier arrangement and representative of the average power of the input voltage signal within a range of voltages at the input.

Power measurement circuit

A materials handling device suitable for mounting on a structure, such as a pickup truck, so that heavy materials, such as cylindrical bales of hay, can be selectively loaded and unloaded onto the pickup truck for transportation from one location to another. The materials handling device comprises a housing assembly pivotally connected to the support structure so that the housing assembly is substantially vertically disposed adjacent an edge of the support structure; a frame slideably positioned within the housing assembly; a material engaging assembly mounted on the lower end portion of the frame so as to extend in a direction away from the support structure; and a frame and housing actuator assembly disposed between and interconnecting the support structure and the upper end portion of the frame. The actuator assembly, which is pivotally connected to the frame and the support structure, selectively moves the frame between a vertically lowered position and the vertically raised position. When the frame is in the vertically raised position the actuator assembly selectively moves the housing assembly between the vertically disposed position and a horizontally disposed position wherein the housing assembly, and thus the frame, are disposed on the support structure. The materials handling device further includes a cradle assembly pivotally connected to the support structure so as to be substantially aligned with the housing and the frame, and a cradle actuator assembly disposed between and pivotally connected to the support structure and the cradle assembly.

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Fremont, CA, United States of America

John Perry Myers