Nokia Telecommunications Oy

Nokia Corporation

Nokia Networks Oy

Kim Anh Tran

Chia-sam Wey

Jukka-Pekka Neitiniemi

A Power Amplifier (PA) exhibits non-linear characteristics as a result of Amplitude Modulation-Phase Modulation (AM-PM) conversions resulting in intermodulation. Inter-modulation affects the RF signal spectrum at the output of the PA. The invention presents a method and apparatus for reducing intermodulation generated at the output of a PA as a result of AM-PM conversion. Presented is a RF power detector utilized in feedback control circuitry where the induction of odd-order harmonics into the feedback path acts to reduce AM-PM intermodulation at the output of the PA. The RF power detector comprises an detector input for receiving RF power and a detector output containing a pre-corrected detected voltage. The RF power detector comprises a pre-correcting circuit for generating odd-order harmonics at a specific power level. The pre-correcting circuit induces odd-order harmonics into the detected portion of output power allowing feedback control circuit to compensate for AM conversions.-PM

Combined RF power detector and power precorrector

A compensated RF power detector utilized in power control circuits for preventing power amplifier saturation. A power amplifier uses a power control circuit to maintain the power amplifier as efficiently and linearly as possible without distortion. The operating point of the power amplifier is defined as close to the 1 dB gain compression point as possible for maximum efficiency and linearity with minimum distortion. However, extreme temperature conditions affect the 1 dB gain compression point causing the power amplifier to operate too close to saturation resulting in distortion or spectral growth. In an embodiment, the compensated RF power detector comprises a RF power detector and a variable RC circuit. The RF power detector has a RF input for receiving RF power, a detector output for supplying a compensated detected voltage and, a detecting diode for generating a detected voltage in response to the received RF power. The detecting diode has an anode coupled to the RF input and a cathode coupled to the detector output. The variable RC circuit comprises a capacitor and a control circuit. The capacitor has a first lead coupled to the cathode of the detecting diode and a second lead coupled to the control circuit. The control circuit has a control output containing a varying resistance coupled to the second lead of the capacitor. The variations in the varying resistance result in the compensation of the detected voltage.

Compensated RF power detector

A temperature compensated variable attenuator comprising a variable attenuator having at least one diode with temperature variations across the at least one diode producing a temperature offset signal. A bias source coupled to the variable attenuator supplies a biasing signal to the at least one diode through a temperature compensation source. The temperature compensation source is coupled between the bias source and the variable attenuator with the temperature compensation source comprising at least one diode capable of producing a temperature offset signal approximately equivalent to the temperature offset signal produced by the first at least one diode. The approximate temperature offset signal subtracted from the biasing signal produces a temperature compensated bias signal that is supplied to the variable attenuator.

Temperature compensated variable attenuator

A precision-controlled logarithmic amplifier having reduced interference parameters. In an embodiment, the invention comprises a logarithmic amplifier having an output signal providing a logarithmic representation of an input signal. A precision-control circuit is coupled to the logarithmic amplifier. The precision-control circuit produces a bias and a saturation current that act to reduce the effects of bias and saturation currents that are produced in the logarithmic amplifier and affect the output signal of the logarithmic amplifier.

Precision-controlled logarithmic amplifier

A controlled detector circuit for generating a detector current to the input of a selected circuit. An unwanted operational voltage is generated on the input of the selected circuit affecting the precision of the detector circuit. The controlled detector circuit comprises a detector circuit having an RF input for detecting a RF signal and a detector output for providing the detector current. Operation of the detector circuit generates a voltage drop affecting the precision of the detector current. A control circuit having a control output connected to the detector output generates a control voltage for reducing the unwanted parameters affecting the precision of the detector current.

Growing community of inventors

Garland, TX, United States of America

Kim Anh Tran