A method for measuring frequency domain characteristics of a PDN having an output terminal connected to a power supply end of a functional circuit. The method includes: a to-be-measured output interface of the functional circuit is acquired; the to-be-measured output interface is controlled to output a first level signal having a first preset rule; remaining at least one output interface of the functional circuit, other than the to-be-measured output interface, is controlled to output a second level signal having a second preset rule according to a first frequency; changing voltage values corresponding to the first frequency and output by the to-be-measured output interface are acquired; and a characteristic impedance of the PDN at the first frequency is determined based on the changing voltage values corresponding to the first frequency.

A method for measuring frequency domain characteristics of a PDN having an output terminal connected to a power supply end of a functional circuit. The method includes: a to-be-measured output interface of the functional circuit is acquired; the to-be-measured output interface is controlled to output a first level signal having a first preset rule; remaining at least one output interface of the functional circuit, other than the to-be-measured output interface, is controlled to output a second level signal having a second preset rule according to a first frequency; changing voltage values corresponding to the first frequency and output by the to-be-measured output interface are acquired; and a characteristic impedance of the PDN at the first frequency is determined based on the changing voltage values corresponding to the first frequency.

A method for multiphase frequency to voltage conversion includes generating for each cycle of an oscillating input, one of a plurality of non-overlapping clocks. A respective voltage in proportion to an input frequency of the oscillating input, is generated in response to each of the non-overlapping clocks, with a respective one of a plurality of frequency to voltage converters. Each of the respective voltages is summated to generate a voltage sum proportional to the input frequency.

A frequency sensor is provided. The frequency sensor may include: a magnetoresistive nano-oscillator including a magnetic heterostructure of at least a magnetic free layer, a magnetic reference layer and a non-magnetic intermediate layer arranged between the magnetic free layer and the magnetic reference layer; a coupling arrangement for coupling an incoming signal to at least one magnetic mode of the magnetic free layer, and a frequency estimator. The frequency estimator may be configured to: perform a plurality of voltage measurements across the magnetoresistive nano-oscillator over time; calculate a time averaged voltage across the magnetoresistive nano-oscillator based on the plurality of voltage measurements; estimate, over a finite range of frequencies, a frequency of the incoming signal based on the calculated time averaged voltage, and output a signal representative of the estimated frequency. A method of estimating a frequency of an incoming signal is also provided.

A frequency sensor is provided. The frequency sensor may include: a magnetoresistive nano-oscillator including a magnetic heterostructure of at least a magnetic free layer, a magnetic reference layer and a non-magnetic intermediate layer arranged between the magnetic free layer and the magnetic reference layer; a coupling arrangement for coupling an incoming signal to at least one magnetic mode of the magnetic free layer, and a frequency estimator. The frequency estimator may be configured to: perform a plurality of voltage measurements across the magnetoresistive nano-oscillator over time; calculate a time averaged voltage across the magnetoresistive nano-oscillator based on the plurality of voltage measurements; estimate, over a finite range of frequencies, a frequency of the incoming signal based on the calculated time averaged voltage, and output a signal representative of the estimated frequency. A method of estimating a frequency of an incoming signal is also provided.

A method for multiphase frequency to voltage conversion includes generating for each cycle of an oscillating input, one of a plurality of non-overlapping clocks. A respective voltage in proportion to an input frequency of the oscillating input, is generated in response to each of the non-overlapping clocks, with a respective one of a plurality of frequency to voltage converters. Each of the respective voltages is summated to generate a voltage sum proportional to the input frequency.

A method for multiphase frequency to voltage conversion includes generating for each cycle of an oscillating input, one of a plurality of non-overlapping clocks. A respective voltage in proportion to an input frequency of the oscillating input, is generated in response to each of the non-overlapping clocks, with a respective one of a plurality of frequency to voltage converters. Each of the respective voltages is summated to generate a voltage sum proportional to the input frequency.

A semiconductor device includes a clock generator which receives an input clock and generates an output clock, a reference voltage generator which receives the input clock or the output clock, generates a sub-reference voltage in accordance with a frequency of the input clock or a frequency of the output clock, and generates a reference voltage using the sub-reference voltage and a preset error voltage, and a clock detector which receives the output clock, generates a first output voltage in accordance with the output clock, and compares the generated first output voltage with the reference voltage to output an error signal based on the output clock, wherein the preset error voltage is set in accordance with a degree of preset error of the output clock.

A measurement data based method for identifying wind turbine generators which cause sub-synchronous oscillations in a complex power system has a theoretical foundation of the open-loop modal resonance and the parallel filter design. The advantages of the present invention are as follows. 1) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system using measurement data instead of parametric model. Hence, it simplifies the computation and reduces the modeling cost effectively. 2) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system precisely with reduced amount of measurement data, reducing the cost of hardware and data measurement effectively. 3) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system based on the open-loop modal resonance theory.

A fluxgate detector for buried and abandoned chemical weapons is provided, comprising: a probe for sensing an external magnetic field, comprising a probe input and a probe output; an excitation module electrically connected to the probe input for inputting an excitation signal into the probe; a frequency selection module electrically connected to the probe output for isolating a second harmonic signal in an induced voltage generated by the probe; and a signal acquisition module electrically connected to the frequency selection module. The second harmonic signal in the induced voltage can be isolated by the frequency selection module, transmitted to the signal acquisition module, and converted to an intensity of the magnetic field by the signal acquisition module. The substance detected can be identified according to the intensity of the magnetic field, so that the buried ACWs can be found efficiently and accurately.