43 results about "Third order intermodulation distortion" patented technology

Field effect transistors having a power density of greater than 25 W/mm when operated at a frequency of at least 4 GHz are provided. The power density may be at least 30 W/mm when operated at 4 GHz. The power density of at least 30 W/mm may be provided at a drain voltage of 120 V. Transistors with a power density of at least 30 W/mm when operated at 8 GHz are also provided. The power density of at least 30 W/mm may be provided at a drain voltage of 120 V. Field effect transistors having a power density of greater than 20 W/mm when operated at a frequency of at least 10 GHz are also provided. Field effect transistors having a power density of at least 2.5 W/mm and a two tone linearity of at least −30 dBc of third order intermodulation distortion at a center frequency of at least 4 GHz and a power added efficiency (PAE) of at least 40% are also provided.

The invention relates to an automatic testing method of mixer third-order intermodulation distortion inside a radio frequency tuner chip, in particular to an automatic testing method of mixer third-order intermodulation distortion inside a DVB-C digital television tuner chip. The automatic testing method adopts the radio frequency apparatus made by Agilent Company as the testing platform. The main equipment of the testing method comprises an Agilent spectrum analyzer E4402B, an Agilent vector signal generator E4438C, an Agilent digital power supply E3649A, an Agilent GPIB link module 82357A and a computer. By means of the IEEE488 communication protocol, the programmable apparatus standard command (SCPI) and chip I<2>C control protocol, test software controls the operating state of the chip and sets and reads relevant parameter of a testing apparatus through the read-write operation of a register arranged inside a tuner chip, thereby realizing automatic radio frequency testing. In addition, the test software consists of an IEEE488 drive module, a parallel port drive module, an I<2>C module and a mixer test module.

A distortion compensating circuit for a power amplifier attains raised compensating accuracy with shorter convergence time by accurately and quickly generating a distortion compensation signal for predistortion. An error signal representing the difference between the input and output signals of the power amplifier is generated. From the error signal and the input signal, the coefficients of the third-order intermodulation distortion, fifth-order intermodulation distortion and seventh-order intermodulation distortion are calculated. According to these coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions is generated.

The invention belongs to the photoelectric technology field and relates to a wideband linearization photonic time-stretch analog-to-digital conversion (PTS-ADC) method and device. The method has the beneficial effects that single-sideband modulation is achieved by utilizing dual-drive M-Z modulators, thus eliminating baseband signal power attenuation caused by dispersion and achieving improvement of the effective analog bandwidth; distortion caused by dispersion introduction phase shifting is eliminated and timing recovery of zero phase shifting distorted signals is achieved by the phase compensation technology; radio-over-fiber signals with complementary characteristics are obtained by adopting two M-Z modulators respectively biased at linear bias points of a falling edge and a rising edge; envelope removal of the radio-over-fiber signals and suppression of second harmonics and second-order and third-order intermodulation distortion are achieved through difference and arcsine algorithm processing in a digital signal processor, thus achieving the effect of obviously improving the system linearity and quantization precision; besides, synchronous stretch of complementary output signals of the two modulators is achieved by utilizing two circulators, thus reducing the system cost and ensuring the consistency of the stretching ratios.

A predistortion method for CMOS Low-Noise-Amplifiers (LNAs) to be used in Broadband Wireless applications is presented. The method is based on the nulling of the third order Intermodulation distortion (IMD3) of the main amplifier by a highly nonlinear predistortion branch. Maximum third order product cancellation is ensured by a transformer feedback method. The technique improves linearity in a wide range of input power without significant gain and Noise Figure. (NF) degradation. Simulation results on a 1-V LNA indicate a 10.3 dB improvement in the Input Third-Order Intercept Point (IIP3) with a reduction of only 1 dB and 0.44dB in amplifier gain and NF respectively.

A signal transmission apparatus including: a plurality of modulating sections configured to modulate a transmission object signal; and a plurality of demodulating sections configured to demodulate the modulated signals modulated by the modulating sections, wherein each of carrier frequencies as frequencies different from each other used by respective sets of the modulating sections and the demodulating sections is set such that frequency of a third-order intermodulation distortion component generated on a basis of two carrier frequencies adjacent to each other is not present within any of reception bands of modulated signals based on each of the other carrier frequencies.

A multistage amplifying device for amplifying a desired signal comprise first to N-th amplifiers connected in cascade,wherein the k-th (k is 1 to N) amplifier includes a k-th amplification section; and a k-th feedback section which has a reactance component, changes a phase of a signal output from the k-th amplification section. When a phase difference between the desired signal output from the N-th amplifier and a third-order inter-modulation distortion(IM3) output from the (N-1)-th amplifier is referred to as a first phase, and a phase difference between the desired signal output from the N-th amplifier, and a combined IM3 obtained by combining a IM3 occurring in the N-th amplification section and a IM3 fed back from the N-th feedback section is referred to as a second phase, a difference between the first phase and the second phase is 120° or more and 180° or less.

A distortion compensating circuit for a power amplifier attains raised compensating accuracy with shorter convergence time by accurately and quickly generating a distortion compensation signal for pre-distortion. An error signal representing the difference between the input and output signals of the power amplifier is generated. From the error signal and the input signal, the coefficients of the third-order intermodulation distortion, fifth-order intermodulation distortion and seventh-order intermodulation distortion are calculated. According to these coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions is generated.

A method and apparatus for compensating for third-order intermodulation (IM) distortion in a receiver by passing a received signal through a detector to obtain a second-order difference signal, combining the 2nd-order signal with the received signal in a multiplier to obtain a 3rd-order IM signal, adjusting a parameter such as amplitude, phase or quadrature amplitude of the 3rd-order IM signal, and coupling the 3rd-order IM signal into the received signal.

A microwave photonic third-order intermodulation distortion complete suppression system based on the DPMZM comprises a microwave source, a phase control module, a bias control module, a laser, the DPMZM and a photoelectric detector. By the phase control module, the four radio frequency electric signals loaded on the four driving electrodes of the dual driving DPMZM possess the fixed phase difference, a DC bias control unit is combined to carry out the DC bias point control on the uplink MZM and the downlink MZM of the DPMZM, and the phase difference control among the four radiofrequency signals is realized by utilizing two 180-degree phase shifters, thereby realizing the third-order intermodulation complete suppression of a broadband microwave photonic communication link. The microwave photonic third-order intermodulation distortion complete suppression system based on the DPMZM has the characteristics of being low in design complexity, high in stability and good in repeatability and being simple to realize, can solve the broadband microwave photonic communication high linearization demand, and guarantees the high bandwidth and large dynamic range of a broadband microwave photonic communication system.

The invention discloses a distribution method of third-order intermodulation distortion parameters applied inside a receiver radio-frequency system circuit, which belongs to the technical field of electromagnetic compatibility. The distribution method comprises the following steps: firstly processing the overall receiving performance index of a receiver radio-frequency system according to nonparasitic response to obtain a threshold voltage; then computing the total distortion voltage of third-order intermodulation distortion in each level of sub circuit, which is about to enter a received passband according to constraint relation; and finally obtaining the third-order cut-off point of each level of sub circuit according to the relation that the total distortion voltage is smaller than and equal to the threshold voltage. The method of the invention realizes the distribution of the third-order intermodulation distortion parameters of each level of sub circuit under the condition of cascade circuit voltage signal in-phase, thereby the problem of poor communication quality caused by overlarge third-order intermodulation distortion signal interference of the receiver radio-frequency system is solved.

The invention belongs to the technical field of microwave photonic signal transmission and processing and discloses a method for improving the linearity of a directly modulated microwave photonic link based on a push-pull structure and an adaptive post-compensation algorithm. The method comprises the following steps: (a) dividing an initial signal into upper and lower signals; (b) performing push-pull modulation on the upper and lower signals; (c) suppressing an even-order distortion signal by using balance detection; (d) suppressing a third-order intermodulation distortion signal (IMD3) by using the adaptive post-compensation algorithm. The method realizes a large-broadband high-linearity directly modulated microwave photonic link in which all even-order distortion signals and the third-order intermodulation distortion signals are suppressed, and the method has the characteristics of low cost, compact structure and high cost performance.