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73results about "Parametric amplifiers" patented technology

Digital phase lock amplifier

The invention discloses a digital phase lock amplifier which comprises a signal passage (1), a reference passage (2) and a signal processor (3), wherein the signal passage (1) is connected with the signal processor (3) through an analog to digital converter (4); the signal processor (3) comprises a frequency measurement module (31), a phase detection discriminator (32), a Cordic generator (33), and a first low pass filter (34) and a second low pass filter (34'). The reference passage (2) forms two paths to output to the signal processor (3) through a signal shaping circuit module (22); one path of the reference passage (2) is input to the Cordic generator (33) through the frequency measurement module (31), and the other path of the reference passage (2) is input to the Cordic generator (33) through a phase shifting module (7) and the phase detection discriminator (32); and the sine and cosine signals output by the Cordic generator (33) are multiplied by the input signal of the signal passage (1) respectively, and are output through the first and second low pass filters (34 and 34') and digital to a first D/A converter (5) and a second D/A converter (5') in sequence. Compared with the prior art, the digital phase lock amplifier has the advantages of high precision, wide frequency band and stable data, and improves the phase precision and eliminates the frequency nonlinearity of an analog channel.
Owner:SUN YAT SEN UNIV

Biphase digital phase-locking amplifier and digital domain synchronous phase-locking algorithm thereof

The invention relates to a biphase digital phase-locking amplifier (as shown in chart 1) and a digital domain synchronous phase-locking algorithm of the biphase digital phase-locking amplifier. The biphase digital phase-locking amplifier can be used for detecting weak current signals, and realize the functions of automatic filtering tracking and synchronous phase-locking. The biphase digital phase-locking amplifier can solve the problems that the volume of the existing phase-locking amplifier is large, the temperature excursion exists, and the speed is slow when the existing phase-locking amplifier is connected with a computer to carry out automatic measurement and control. The biphase digital phase-locking amplifier has the technical characteristics that the weak current signals pass through a 9-step RLC (radio link control) mixed type high-pass filter by a precise I/V conversion circuit, and is then connected with two low-noise instrument amplifiers, the connecting modes of which are different; the rear ends of the instrument amplifiers are respectively connected with an 8-step RLC mixed type high-pass filter, and a differential signal is formed by signals output by two low-pass filters. Meanwhile, reference signals pass through a 90-degree phase shifter of a phase-locking loop to output two TTL square waves, the phase difference of two phases of which is 90 degrees. Signals of three paths are collected by a data acquisition card, and are then transmitted to a PC (personal computer) machine. The biphase digital domain synchronous phase-locking algorithm (as shown in chart 2) provided by the invention is applied on the PC machine to carry out signal processing and filtering.
Owner:CAPITAL NORMAL UNIVERSITY

Lock-in amplifier of analog-digital mixed structure and lock-in amplification method of lock-in amplifier

The invention discloses a lock-in amplifier of an analog-digital mixed structure and a lock-in amplification method of the lock-in amplifier. The lock-in amplifier comprises an input signal processing system, a reference signal generation system, an analog processing system, an analog-to-digital conversion system and a digital processing system, wherein the first output end and the second output end of the reference signal generation system output two paths of sine wave reference signals which are mutually orthogonal; the analog processing system comprises two analog multipliers and an analog low-pass filter; the digital processing system comprises two digital low-pass filters and a digital operational unit. According to the lock-in amplifier, an aliasing signal is allowed to exist in a signal detection process; through the combination of the analog low-pass filter and the digital low-pass filters, an interference signal in an input signal can be effectively filtered, and a high-frequency interference signal and the aliasing signal are filtered, so that various frequency signals can be detected, the signal to noise ratio is effectively improved, hardware requirements are reduced, and the production cost is lower; the lock-in amplifier can be widely applied to the field of weak signal measurement.
Owner:SYSU CMU SHUNDE INT JOINT RES INST +1

Lock-in amplifier circuit for detecting terahertz pulse signals

The invention belongs to the technical field of the detection of weak signals and particularly relates to a lock-in amplifier circuit for detecting terahertz pulse signals. The lock-in amplifier circuit comprises a photoelectric detector used for detecting the terahertz pulse signals, a pre-amplification module, a phase shift module and a phase-sensitive detection module. The lock-in amplifier circuit is characterized in that: signals to be detected which are acquired by the photoelectric detector are processed by the pre-amplification module and are connected to one input end of the phase-sensitive detection module; reference signals after the phase shifting operation by the phase shift module are connected to the other input end of the phase-sensitive detection module; the output end ofthe phase-sensitive detection module outputs signals; the pre-amplification module comprises a band-pass filter circuit and a second-order amplifying circuit which are sequentially connected; the phase shift module consists of a CD-951V4 chip and peripheral circuits of the CD-951V4 chip; and the phase-sensitive detection module consists of a CD552-R3 chip and periphery circuits of the CD552-R3 chip. The lock-in amplifier circuit can detect microvolt-level low-voltage signals with the noise of millivolt level, and is suitable for small-signal and intensive-background noise occasions such as signals acquiring of terahertz time-domain spectrometer, wherein the signal-to-noise ratio of output signals reaches over 50:1.
Owner:TIANJIN UNIV

Dual-phase lock-in amplifier based on DSP (Digital Signal Processor) and LabVIEW

The invention discloses a digital dual-phase lock-in amplifier based on a DSP (Digital Signal Processor) and LabVIEW, belongs to the field of weak signal detection, and aims to solve the problem of poor detection effect on weak sinusoidal signals of known frequencies submerged in noises in existing medium and low-level dual-phase lock-in amplifiers. The digital dual-phase lock-in amplifier comprises a signal conditioning module, a DSP module and a LabVIEW software module, wherein the signal conditioning module is used for inputting tested signals into the DSP module after amplification, low-pass filtering and direct-current biasing; the DSP module is used for sampling the conditioned tested signal to obtain a tested signal sequence, generating a sinusoidal reference signal sequence and a cosine reference signal sequence having the same frequency as the tested signals, multiplying the sinusoidal reference signal sequence and the cosine reference signal sequence with the tested signal sequence respectively, and transmitting results of two multiplying operations; and the LabVIEW software module is used for receiving the results of the two multiplying operations, performing the low-pass filtering on the results to obtain stable direct-current constants, solving amplitudes and phases of the tested signals according to the direct-current constants, and displaying the amplitudes, phases and waveforms of the tested signals. The digital dual-phase lock-in amplifier is used for detecting the weak signals submerged in the noises.
Owner:HARBIN INST OF TECH

Digital phase locking amplifier and digital phase locking control method

The invention discloses a digital phase locking amplifier and a digital phase locking control method. The digital phase locking amplifier comprises a pre-amplifier and a micro-processor. The pre-amplifier is used for amplifying a tested analogue signal, inputting the tested analogue signal into an analogue-digital converter, converting the amplified tested analogue signal into a digital signal, and inputting the digital signal into the micro-processor through a Px interface. The micro-processor is used for controlling the gain of the pre-amplifier through a Py interface according to the amplitude of the digital signal, processing the digital signal, detecting the digital signal with the pre-set frequency in the digital signal, and outputting the digital signal with the pre-set frequency through a Pz interface. The control method comprises the following steps: the micro-processor controls the analogue-digital converter to sample the tested analogue signal according to the speed which is 4M times of that of the pre-set frequency F0, represented in the equation of fs=4M*f0, so as to obtain a sampling signal; the micro-processor downwardly samples the sampling frequency fs=4M*f0 to 4*f0; two orthogonal components RS and RC of the tested analogue signal are calculated according to the sampling signal; and the amplitude A and the phase angle of the tested analogue signal can be obtained by calculation.
Owner:TIANJIN UNIV

Digital phase lock amplifying experimental device

The invention provides a digital phase lock amplifying experimental device. The experimental device comprises a power supply module, a digital module, a generator module, an analog module and a front panel module. The power supply module is sequentially connected with the digital module, the analog module, the front panel module and the generator module. The digital module is respectively connected with the analog module, the front panel module and the generator module. With no direct current amplifier equipped inside an output channel, the digital lock phase amplifier is enabled to suffer no interference generated by instability of the direct current amplifier working performances with the time change and the temperature drift of the direct current amplifier due to the temperature change and further alleviate the error due to the instability of a reference signal. A digital signal processing unit can achieve a phase lock function in a shortest time or even with no time delay. The digital phase lock amplifying experimental device is especially advantageous in terms of frequency scanning measurement. By adopting the high-performance quadrature demodulation technology of the digital lock phase amplifier, the detection precision of weak signals can be significantly improved. The cost performance of the digital lock phase amplifier is obviously increased. The digital phase lock amplifying experimental device is thus more influential in the measuring technical field.
Owner:天津港东科技股份有限公司
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