CN205388624U

CN205388624U - Phase difference measurement circuit based on integrated phase detection discriminator

Info

Publication number: CN205388624U
Application number: CN201620233454.8U
Authority: CN
Inventors: 司朝良
Original assignee: Shandong Jiaotong University
Current assignee: Shandong Jiaotong University
Priority date: 2016-03-18
Filing date: 2016-03-18
Publication date: 2016-07-20
Anticipated expiration: 2026-03-18

Abstract

The utility model discloses a phase difference measurement circuit based on integrated phase detection discriminator, including two ac couplings and DC bias circuit, two PECL comparators, integrated phase detection discriminator MCH12140, the active proportional -integral -filter of differential input, AD converter, microcontroller STC12C5204AD and displays. The utility model discloses the circuit utilizes the comparator to two way signal standardizations, is compared obtaining the phase difference pulse mutually by integrated phase detection discriminator, after active proportional integral filtering, AD conversion, obtains the phase difference result by microcontroller calculation and sends to the demonstration. Use multipurposely the high -speed congruence bipolarity analog -to -digital conversion technique of reflecting, microcontroller control realize down to the input of two tunnel in broad frequency range wave form may not with with signal phase difference accurate measurement within a definite time frequently, still expanded the application of phase detection discriminator.

Description

Phase difference measuring circuit based on integrated phase detection discriminator

Technical field

This utility model relates to the signal phase difference measurements technology of electronic measuring technology field, is specifically related to a kind of phase difference measuring circuit based on integrated phase detection discriminator.

Background technology

Phase difference measurement is a requisite content in signal measurement, and the phase difference measurement technology between same frequency signal is significant to modern communications, industrial measurement and control and national defense construction.Existing method for measuring phase difference and circuit are a lot, and most basic measurement means is to adopt oscillograph measurement, it would however also be possible to employ based on voltage measurement method or the pulse counting method of XOR gate, also have based on the Function Calculation of DSP, fourier transform method etc..The shortcoming that existing method for measuring phase difference is had nothing in common with each other, otherwise the restriction certainty of measurement by artificial reading factor is relatively low, or be that measurement frequency is low, or measuring circuit is complicated, cost is high.

Summary of the invention

This utility model is based on integrated phase detection discriminator, by A/D conversion, the phase contrast of two same frequency signals is converted to digital quantity, control and under computing at MCU, accurately obtain the phase contrast between two signals that waveform is identical or different, circuit is simple, measure accurately, can measured frequency scope very wide, also extend the range of application of integrated phase detection discriminator.

Phase difference measuring circuit based on integrated phase detection discriminator of the present utility model, including two AC coupled and DC bias circuit, two PECL comparators, integrated phase detection discriminator MCH12140, the active proportional-integral filter of Differential Input, A/D converter AD976A, microcontroller STC12C5204AD and display, it is characterized in that: two-way input to be measured signal is after respective AC coupled with DC bias circuit, it is separately input to the in-phase end of two PECL comparators, the anti-phase termination fixed level of two PECL comparators；The output of two PECL comparators is separately input to two inputs of integrated phase detection discriminator MCH12140；The both-end output of described integrated phase detection discriminator MCH12140 is connected respectively to two inputs of the active proportional-integral filter of Differential Input；The output signal of described active proportional-integral filter is input to the analog voltage input of A/D converter AD976A；The digital signal of described A/D converter AD976A output is input to the data wire of microcontroller STC12C5204AD；The digital signal that A/D converter is sent here by described microcontroller STC12C5204AD is calculated, and the phase contrast result of calculating is exported display and shows.

Phase difference measuring circuit based on integrated phase detection discriminator of the present utility model, the described active proportional-integral filter of Differential Input is made up of with peripheral resistance, capacity cell integrated operational amplifier LT1028.

The beneficial effects of the utility model are: by PECL comparator shaping, utilize integrated phase frequency detector and A/D converter, it is capable of the phase difference measurement between the identical or different waveshape signals such as sine wave, sawtooth waveforms, triangular wave, square wave, and certainty of measurement is high, can surveying signal frequency height, circuit is relatively simple.Extend the application of integrated phase frequency detector simultaneously.

Accompanying drawing explanation

Fig. 1 is theory diagram of the present utility model；Fig. 2 is partial circuit diagram of the present utility model, containing two AC coupled and DC bias circuit, two PECL comparators, phase detection discriminator MCH12140, the active proportional-integral filter of Differential Input formula；Accompanying drawing 3 is phase detection discriminator working waveform figure of the present utility model.

In Fig. 2: 1 AC coupled and DC bias circuit 1,2 AC coupled and DC bias circuit 2, the 3 active proportional-integral filter of Differential Input formula.

Detailed description of the invention

In conjunction with accompanying drawing, phase difference measuring circuit based on integrated phase detection discriminator of the present utility model, it includes the working power that AC coupled is necessary with DC bias circuit 1 (1), AC coupled and DC bias circuit 2 (2), two PECL comparators, phase detection discriminator MCH12140, the active proportional-integral filter of Differential Input (3), A/D converter AD976A, microcontroller STC12C5204AD, display, auxiliary resistance R3 and R4 and+5V ,-5V ,+3V etc..

Two AC coupled are identical with the structure of DC bias circuit and parameter, and the fixed level numerical value of two comparator ADCMP553 end of oppisite phase is also identical.The output of PECL comparator ADCMP553, it is possible to be directly connected with phase detection discriminator MCH12140.Two-way input signal to be measured, after comparator shaping, is separately input to two inputs R, V of integrated phase detection discriminator MCH12140 from the QA outfan of comparator.The forward position of two input pulses is only carried out phase demodulation by MCH12140, the phase discriminating pulse of output becomes DC voltage after active proportional integral filter, phase relation according to R, V end input pulse, active proportional integral filter output DC voltage be likely on the occasion of, being likely to as negative value, numerical value is at the maximum positive output voltage U of operational amplifier_om+With maximum negative output voltage U_om-Between change.In the present embodiment, if active proportional integral filter output voltage be on the occasion of, represent input 2 signal phase input in advance 1 signal phase；Otherwise, if the voltage of active proportional integral filter output is negative value, represent that the signal phase of input 1 inputs the signal phase of 2 in advance.Phase contrast between magnitude of voltage linear response two the input measured signal of this active proportional integral filter output, after bipolarity A/D converter AD976A changes, is calculated by microcontroller STC12C5204AD and obtains phase difference value to be measured.

AD976A is 16 bipolarity A/D converters, and its output coded system is the complement of two's two's complement, and highest order is sign bit, and 0 represents positive voltage, and 1 represents negative voltage.STC12C5204AD judges the positive and negative value of voltage according to sign bit, is then calculated according to the result of data supplement.The reference voltage V of AD976A_REFCan adopting+2.5V the reference voltage in sheet, it is also possible to external high stability voltage source, the analog voltage input range of this A/D converter is-4V_REF～+4V_REF。

The phase demodulation of MCH12140 exports after active proportional-integral filter, shown in its overall phase detection gain K such as formula (1):

U in formula (1)_om+、U_om-It is the maximum positive voltage of the actual output of LT1028 and maximum negative voltage respectively.

For ensureing certainty of measurement, active proportional-integral filter circuit needs to return to zero.Inputting 1 end, input 2 ends and input two identical signals of phase place respectively, the value regulating R5, R6 makes the LT1028 DC voltage exported be zero；When then measuring and record phase contrast respectively+2 π and-2 π of two input signals to be measured, the U of the actual correspondence output of LT1028_om+And U_om-Value, it is provided that to STC12C5204AD, is pressed formula (1) by STC12C5204AD and calculates phase detection gain K.

In the present embodiment, the reference voltage of bipolarity A/D converter AD976A selects the+2.5V reference voltage in sheet；Passing through programmed configurations so that it is input analog voltage can be surveyed and range for-5V～+5V, namely its full range voltage is 10V, and its minimum voltage resolution is 0.152mV, it is ensured that the certainty of measurement of phase contrast.

If the decimal number that the binary number of AD976A output obtains after STC12C5204AD complement arithmetic is D₁₀, then the phase contrast radian number surveyed is shown in formula (2):

Comparator and phase detection discriminator all adopt PECL level device, and operating frequency is significantly high, and the offset voltage of ADCMP553 comparator is only 2mV, and the impact of certainty of measurement is very little.The discriminator sensitivity of MCH12140 is also significantly high simultaneously.This example circuit can measure that frequency reaches 500MHz, virtual value is the phase contrast of two sinusoidal signals of 20mV～1.06V, and the dynamic range that can survey pulse signal is 20mV～3V, and certainty of measurement is higher.

Claims

1. based on the phase difference measuring circuit of integrated phase detection discriminator, including two AC coupled and DC bias circuit, two PECL comparators, integrated phase detection discriminator MCH12140, the active proportional-integral filter of Differential Input, A/D converter AD976A, microcontroller STC12C5204AD and display, it is characterized in that: two-way input to be measured signal is after respective AC coupled with DC bias circuit, it is separately input to the in-phase end of two PECL comparators, the anti-phase termination fixed level of two PECL comparators；The output of two PECL comparators is separately input to two inputs of integrated phase detection discriminator MCH12140；The both-end output of described integrated phase detection discriminator MCH12140 is connected respectively to two inputs of the active proportional-integral filter of Differential Input；The output signal of described active proportional-integral filter is input to the analog voltage input of A/D converter AD976A；The digital signal of described A/D converter AD976A output is input to the data wire of microcontroller STC12C5204AD；The digital signal that A/D converter is sent here by described microcontroller STC12C5204AD is calculated, and the phase contrast result of calculating is exported display and shows.

2. the phase difference measuring circuit based on integrated phase detection discriminator according to claim 1, it is characterised in that: the active proportional-integral filter of described Differential Input is made up of with peripheral resistance, capacity cell integrated operational amplifier LT1028.