Microwave VCO directly-modulated high-linearity frequency modulated signal generating circuit
A technology of frequency modulation signal and generating circuit, applied in the direction of pulse shaping, etc., can solve the problems of complex circuit implementation, low cost, narrow frequency sweep bandwidth, etc., to improve the linear accuracy of frequency sweep, unrestricted frequency sweep rate, and reduce distance measurement effect of error
Active Publication Date: 2014-10-01
10TH RES INST OF CETC
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Problems solved by technology
At present, linear sweep signals are mainly generated by frequency synthesizers or directly modulated by microwave voltage-controlled oscillators (VCO). The former can achieve good linearity, but the achievable sweep rate is low and the sweep bandwidth is also narrow. The circuit is complicated and the cost is high
Microwave VCO direct modulation has no frequency sweep rate limit, and the sweep bandwidth is only limited by the maximum tuning bandwidth of the VCO. The cost is low, but the sweep linearity is poor, which generally does not meet the requireme
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[0018] exist figure 1 In the shown microwave VCO direct modulation high-chirp signal generation circuit, simple pulse shaping and differential circuits can be used to generate periodic nonlinear ramp-down sawtooth wave scanning voltage waveforms, and the microwave VCO can be directly modulated to generate chirp signal output. The circuit includes a monostable pulse shaping circuit 1, a C-R differential circuit 2, a bias resistor 3, a microwave voltage-controlled oscillator VCO4 and a microwave switch 5. The monostable pulse shaping circuit 1 adopts a monostable flip-flop integrated circuit externally connected with a timing resistor R t and timing capacitor C t accomplish. The differential circuit 2 consists of resistors R connected in series between the input terminal and the output terminal in sequence 1 , Differential capacitance C 1 , and a ground resistor R in parallel between the output terminal and ground 2 composition. The differential circuit 2 differentiates th...
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The invention provides a microwave VCO directly-modulated high-linearity frequency modulated signal generating circuit. According to the microwave linearity frequency modulated signal generating circuit, frequency sweeping linear precision and frequency sweeping rate of more than two orders are not limited, and frequency modulated continuous wave radar intermediate-frequency spurious signals caused by cross mixing can be restrained. According to the technical scheme, a monostable pulse shaping circuit performs shaping on input periodic pulse signals for triggering frequency sweeping signals to form pulse signals with the pulse width equal to the frequency sweeping time in one period, nonlinear inclined-down sawtooth wave voltage signals generated by a C-R differentiating circuit are overlaid on a direct-current bias voltage V0, a frequency sweeping control voltage signal compensated with nonlinear frequency modulated voltage-frequency characteristics of a microwave VCO (4) is formed, and the oscillation frequency of the microwave VCO is controlled to change linearly with the passage of time. The pulse signals generated by shaping control a microwave switch to perform gating on the output of the microwave VCO, and the interference of the intermediate-frequency spurious signals generated by short-distance strong echoes on the work of the radar is restrained.
Description
technical field [0001] The invention relates to a microwave voltage-controlled oscillator (VCO) which is mainly used in frequency-modulated continuous wave (FMCW) radar to directly modulate a high-linear frequency-modulated signal generating circuit. The frequency-time characteristic curve within the frequency sweep time of the cycle has a linear precision above the second order. Background technique [0002] The Linear Frequency Modulation (LFM) signal is a large time-width-bandwidth product obtained through linear frequency modulation. It is also called a Chirp signal. It is the earliest studied and most widely used pulse compression signal. Radar usually adopts a LFM signal to ensure high resolution while increasing the detection distance. FMCW (Frequency Modulated Continuous Wave) frequency modulation continuous wave system radar has been around for a long time. Its main advantages are small radiation power, high accuracy of distance measurement and speed measurement, r...
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Inventor 黄建
Owner 10TH RES INST OF CETC
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