37results about How to "Wide output frequency range" patented technology

The object of the invention is to obtain a stable, locked clock with reduced output jitter in a digital phase-locked loop circuit. Control oscillating part 12 has frequency divider 18, period measurement circuit 20, moving average value computation circuit 22, and output clock generator 24. In intermediate oscillating frequency divider 18, as a result of tracking to synchronization control signals c, d from phase comparator 10, there is a wide variation in the period of intermediate clock g. However, by means of period measurement circuit 20 and moving average value computation circuit 22, varying slowly with a small fluctuation amplitude, period i of the moving average is obtained, and a stable output clock j that tracks reference clock a slowly and reliably is obtained from output clock generator 24.

The invention provides a built-in oscillation circuit. A negative feedback closed loop circuit type is adopted for the built-in oscillation circuit, and a frequency-voltage conversion mode is used for the built-in oscillation circuit, and therefore the built-in oscillation circuit is enabled to be completely integrated in a chip, crystal oscillators needing to be additionally arranged are saved, and process cost is saved. An oscillation frequency generated by an annular oscillator is converted into a feedback voltage and compared with a reference voltage, then compared results are fed back to a control end of the annular oscillator, the frequency of the annular oscillator is changed, the output frequency deviation is compensated, and therefore work frequency with low temperature drift is output by a loop circuit, and output frequency with high precision is generated.

The present invention provides a low phase noise wideband microwave local oscillator source circuit which is formed by two phase-locked loops. The frequency division signal of a broadband voltage-controlled oscillator directly enters a phase detector to form phase-locked loops with a reference signal, and the preset of the whole loop is realized. Then through switch switching, the output signal of the voltage-controlled oscillator and the frequency doubling and frequency division of a sampling ring output signal are mixed, the phase locking is carried out again, and the function of a low noise is realized. According to the low phase noise wideband microwave local oscillator source circuit, a wideband VCO chip is used, the outputted frequency range is 3GHz to 10GHz, and the phase noise of a 10GHz signal can reach -120dBc/Hz@10kHz. According to the low phase noise wideband microwave local oscillator source circuit, while very low phase noise is obtained, the number of used devices is greatly reduced, a PCB space is saved, the volume is only 16cm by 9cm by 2cm, the debugging difficulty is reduced, and the power consumption is reduced.

The invention discloses a frequency characteristic detecting system of an electronic type voltage transformer. The frequency characteristic detecting system comprises a frequency conversion power supply, a boosting unit, a high frequency voltage divider, a merging unit and a frequency characteristic detecting unit. The nominal voltage of the output end of the frequency conversion power supply adjusts the voltage amplitude of a power supply through the boosting unit to supply the primary side high voltage U1 used in an experiment to the electronic type voltage transformer to be detected; the primary side high voltage U1 is converted into the low voltage U2 through the high frequency voltage divider, and the low voltage U2 is used as standard source signals of the frequency characteristic detecting unit; the sampling value of the electronic type voltage transformer to be detected is sent to the frequency characteristic detecting unit through the merging unit, and the sampling value is used as detected signals of the frequency characteristic detecting unit. The frequency characteristic detecting system of the electronic type voltage transformer can reliably and perfectly detect the frequency characteristics of the electronic type voltage transformer, and aims to improve the frequency transmission performance of the electronic type voltage transformer and provide the technical guarantee for safe and stable operation of the electronic type voltage transformer.

The invention discloses a FPGA-based digital radio frequency transmitter. The digital radio frequency transmitter comprises a frequency conversion and coding module, a radio frequency digital-to-analog conversion module, a combining and filtering module and an electrically tunable filtering module. The main working process of the FPGA-based digital radio frequency transmitter is as follows: a digital baseband signal is subjected to frequency conversion and coding processing of the LUT mapping module to obtain a 1-bit digital signal of a specific frequency band, the 1-bit digital signal is converted into an analog radio frequency signal through the radio frequency digital-to-analog conversion module, and noise components in the analog radio frequency signal are filtered out through the combining filtering module and the electrically tunable filtering module. According to the invention, except the combination filtering module and the electrically tunable filtering module, other processing modules are FPGA-based digital modules; signals with specific frequency and bandwidth can be defined, the frequency modulation range is wide, the integration level is high, and the requirements of modern wireless communication transmitters are met.

The invention discloses a broad-band radio-frequency generation circuit based on a VC-TCXO (Voltage Control-Temperature Compensation Crystal Oscillator) array and a frequency synthesizing chip, which comprises a VC-TCXO (Voltage Control - Temperature Compensation Crystal Oscillator) array, a frequency synthesizing chip, a modulator, a direct digital frequency synthesizer, a power controller and adigital processor; the digital processor is connected with the control end of the VC-TCXO (Voltage Control - Temperature Compensation Crystal Oscillator) array, the control end of the frequency synthesizing chip, the control end of the power controller and the input end of the direct digital frequency synthesizer separately; the output end of the VC-TCXO (Voltage Control - Temperature Compensation Crystal Oscillator) array is connected with the reference input end of the frequency synthesizing chip; the output end of the frequency synthesizing chip is connected with the carrier input end of the modulator; the I/Q baseband output end of the direct digital frequency synthesizer is connected with the I/Q baseband input end of the modulator; and the output end of the modulator is connected with the signal input end of the power controller. The broad-band radio-frequency generation circuit has the advantages of wide output frequency range, high frequency resolution, low noise coefficient, good stray performance and the like.

The invention discloses a three-level and five-level hybrid modulation method for a single-phase inverter, and the method comprises the steps: employing an inverter circuit which comprises a DC powersupply, a field effect transistor, an inductor, a capacitor and a resistor, and enabling an AC side midpoint to be connected with a DC side midpoint N through the inverter circuit in order to reduce acommon-mode voltage; and according to the method, a three-level modulation method and a five-level modulation method are used in a mixed mode, the three-level modulation method is used when the modulation ratio is higher than 0.2, the five-level modulation method is used when the modulation ratio is lower than 0.2, and the method has the following remarkable advantages that the output voltage range is 2-115 V, the output frequency range is 47-10000 Hz; THD can meet the requirement that THD is smaller than 2% through mixed use of the three-level modulation and five-level modulation methods; the circuit is compact in structure and small in size; and the output power is high and can reach 6VA.

The invention discloses a programmable capacitor array-based frequency band phase-locked loop, which is characterized in that a phase frequency detector circuit is sequentially connected with a charge pump circuit, a switch loop filter and a multiband voltage-controlled oscillator circuit, and the multiband voltage-controlled oscillator circuit is connected with the phase frequency detector circuit through a programmable frequency divider circuit; the phase frequency detector circuit is connected with the switch loop filter through the switch control circuit; reference clock signals clkref and clkdiv generate control signals UP and DN through the phase frequency detector, the charge pump converts a received pulse difference signal into a current signal, then the current signal is converted into a voltage signal through the loop filter to be used for controlling the frequency change of the voltage-controlled oscillator, discrete frequency modulation is achieved by changing the load capacitance, and the frequency of the voltage-controlled oscillator is adjusted. A programmable capacitor array structure is utilized to obtain a frequency output range, and output is fed back to a phase frequency detector through a frequency divider to realize loop locking. Under the condition that the gain of the voltage-controlled oscillator is reduced, low phase noise of the voltage-controlled oscillator is achieved, and meanwhile a wide output frequency range is obtained.

The invention discloses a high-precision wide-range relaxation oscillator insensitive to temperature. The relaxation oscillator comprises a bias voltage module (101), a reference current module (102),a programmable current mirror (103), a relaxation oscillator unit (104) and a shaping logic module (105). A programmable charging and discharging current is provided for the relaxation oscillator unit through a bias voltage (101), the reference current module (102) and theprogrammable current mirror (103), and the wide-range frequency characteristic of multi-band output is achieved; coarse adjustment and fine adjustment of the output frequency of each frequency band are realized through frequency adjustment and temperature compensation technologies in the reference current (102), and a high-precision output clock is generated; meanwhile, the positive temperature coefficient characteristic of the resistor and the negative temperature coefficient characteristic of the triode are utilized toachieve the good temperature drift characteristic that the output frequency of the oscillator is insensitive to the temperature in a full temperature range; and the shaping logic module (105) performs comparison, frequency multiplication and feedback control of charging and discharging of a capacitor on the output waveform of the relaxation oscillator unit, and finally outputs a clock signal witha target frequency. The relaxation oscillator provided by the utility model has the characteristics of the wide output frequency range, high precision and insensitivity to temperature.

Provided is a configurable voltage-controlled oscillator applied to an FPGA. A ring oscillator serves as a core part of the voltage-controlled oscillator and is provided with extra digital control signals used for controlling frequency of an oscillation center. The control signals are configured by means of configuration information of the FPGA, center frequency of the voltage-controlled oscillator can be adjusted, and therefore output frequency of the voltage-controlled oscillator can be continuously adjusted within a large range.

The invention relates to an external RC frequency adjustable oscillator in oscillators. The external RC frequency adjustable oscillator comprises a reference voltage generation circuit 1, a charging circuit 2, a discharge circuit3, and a clock processing circuit 4; the reference voltage generation circuit 1 is used for generating and outputting a reference voltage signal, and the discharge circuit3 is used for discharging charges on the capacitor C2; the discharging circuit 3 comprises a comparator, the charging circuit 2 comprises a capacitor C2, and the voltage on the capacitor C2 is directly fed back to the positive input end of the comparator; and the clock processing circuit 4 is used for enhancing driving and shaping of output. The oscillator is wide in output frequency range, simple in structure, small in area and convenient and flexible to use, and can be widely applied to MCU and other electronic products needing clocks.