CN103856430B - A kind of OOK receiver data extractors based on displacement peak-value detection method - Google Patents

Abstract

The invention discloses an OOK receiver data separator based on a shift peak detection method. Firstly, the filtered analog baseband signal is passed through the shifter to realize the negative shift of the voltage, and then the shifted signal is detected. The positive peak value is used as the judgment level. Finally, the judgment level signal is compared with the analog baseband signal through a comparator to obtain a digital baseband signal, and the extraction of the digital baseband signal is completed. The specific structure includes a shifter, the first rail-to-rail An operational transconductance amplifier A1, a first PMOS transistor M1, a first capacitor C1, a first resistor R1, a second rail-to-rail operational transconductance amplifier A2, and a second resistor R2. The invention realizes the feature of directly separating the digital signal from the analog signal, has fast response speed, and can adjust the shifted voltage value to adjust the judgment level according to the design requirement, thereby obtaining accurate demodulation signal and high sensitivity.

Description

A Data Separator for OOK Receiver Based on Shifted Peak Detection Method

technical field

The invention relates to an OOK receiver data separator based on a shift peak detection method, which belongs to the signal modulation technology.

Background technique

The on-off keying AM system (OOK) signal is an on-off keying AM signal, which uses on-off at different positions to transmit different information, and the accuracy of the pulse position will determine the final demodulation bit error rate. The information demodulation of wireless communication can be realized by analog circuit or digital circuit. For complex information modulation methods, demodulation is generally implemented in digital circuits; for simple modulation methods such as OOK, analog demodulation has the advantages of simplicity and reliability, but the information obtained from preliminary demodulation is still an analog signal, which needs to be obtained from The digital signal is recovered for processing by the subsequent digital module. Since the information of the signal is reflected in different positions of the envelope, when the position changes, the information contained in it changes. It is necessary to find an effective method to accurately extract the position of the envelope and output '0', '1' signals.

A data separator is a signal processing module that converts a detection signal into a digital signal. The core of the data separator is a high-speed comparator, which compares the detected signal with the decision level to obtain a digital signal for digital processing. The key of the comparator is how to get accurate and effective decision level. There are generally two methods for generating the decision level, that is, the method of averaging voltage and the method of detecting peak value. The average voltage detection method is to obtain the average value of the detection signal as the judgment level by integrating on a large capacitor. It has reliable performance and strong anti-interference ability, but the response speed is slow. When the signal changes suddenly, the detected average value It takes a long time for the response to change; while the peak detection method determines the judgment level through the peak detection and the resistor-capacitor network, the response speed is fast, but the reliability is poor, and the comparator has a fuzzy zone for judgment.

Contents of the invention

Purpose of the invention: in order to overcome the deficiencies in the prior art, the present invention provides a kind of OOK receiver data separator based on shift peak detection method, adopts a kind of peak detection technology based on level shift to provide decision level, by The analog circuit separates the digital baseband signal in the receiver from the analog baseband signal (that is, recovers the digital signal from the detection signal), and has the characteristics of simple structure, fast response speed and high sensitivity.

Technical scheme: in order to achieve the above object, the technical scheme adopted in the present invention is:

An OOK receiver data separator based on a shift peak detection method, comprising a shifter, a first rail-to-rail operational transconductance amplifier A1, a first P-type metal oxide transistor M1, a first capacitor C1, and a first resistor R1 , a second rail-to-rail operational transconductance amplifier A2 and a second resistor R2;

The baseband input signal Vin is connected to the input terminal of the shifter. Firstly, the filtered analog baseband signal passes through the shifter to realize the negative shift of the voltage, and then detects the positive peak value of the shifted signal as the decision level , and finally compare the decision level signal with the analog baseband signal through a comparator to obtain a digital baseband signal, and complete the extraction of the digital baseband signal. The specific structure includes the output terminal Vf of the shifter connected to the first rail-to-rail calculation The negative input terminal of the amplifier A1, one end of the first capacitor C1 and one end of the first resistor R1 are grounded, the other end of the first capacitor C1, the other end of the first resistor R1 and the drain of the first P-type metal oxide transistor M1 The poles are all connected to the positive input terminal of the first rail-to-rail operational transconductance amplifier A1, and the output terminal of the first rail-to-rail operational transconductance amplifier A1 is connected to the gate of the first P-type metal oxide transistor M1, and the first P-type The source of the metal oxide transistor M1 is connected to the power supply voltage, so that the first P-type metal oxide transistor M1, the first capacitor C1 and the first resistor R1 form a feedback charging loop; the positive side of the second rail-to-rail operational transconductance amplifier A2 The input terminal is connected to the baseband input signal Vin, the negative input terminal of the second rail-to-rail operational transconductance amplifier A2 is connected to the drain of the first P-type metal oxide transistor M1, and the second resistor R2 is connected across the second rail-to-rail Between the positive and negative input terminals of the operational transconductance amplifier A2, the output terminal of the second rail-to-rail operational transconductance amplifier A2 is the separated digital baseband signal Vout, and the second resistor R2 is connected across the second rail-to-rail operational transconductance amplifier. Between the positive and negative input terminals of the conduction amplifier A2, a comparator circuit is formed.

Specifically, the shifter includes a third rail-to-rail operational transconductance amplifier A3, a second P-type metal oxide transistor M2, a third resistor R3 and a first current source I1, and the baseband input signal Vin is connected to the third rail to The negative input terminal of the rail operational transconductance amplifier A3, the output terminal of the third rail-to-rail operational transconductance amplifier A3 is connected to the gate of the second PMOS transistor M2, the source of the second PMOS transistor M2 The pole is connected to the power supply voltage, the drain of the second P-type metal oxide transistor M2 is connected to one end of the third resistor R3, and fed back to the positive input end of the third rail-to-rail operational transconductance amplifier A3, and the other end of the third resistor R3 It is connected to the first current source I1 and simultaneously serves as the output terminal Vf of the shifter.

The current value of the first current source I1 is constant, and the required shift voltage value can be obtained by selecting an appropriate resistance value of the third resistor R3. The output signal Vf is different from the input signal Vin by a displacement voltage value, thereby realizing the function of voltage displacement, and the displacement voltage in the circuit of the present invention is 150mV.

Beneficial effects: the OOK receiver data splitter based on the shift peak detection method provided by the present invention improves the method of peak detection of the traditional data splitter to generate the judgment level. First, the level shift operation is performed on the detection signal, and then the Peak detection, the result of peak detection is used as the judgment level of the comparator; the use of the shifter enables the circuit to adjust the shifted voltage value according to actual needs, and finally can separate a more accurate digital baseband signal; it is different from the traditional diode shifter Compared with the shifting voltage value, the bit device is smaller and can be adjusted in size, which improves the sensitivity and accuracy of detection; and because it does not use diodes, it is easier to integrate in CMOS circuits, and has low requirements for power supply voltage, which can achieve higher integration. Spend

Description of drawings

Fig. 1 is the circuit schematic diagram of shift data separator of the present invention;

Fig. 2 is when receiving-65dBm signal, main signal waveform in the circuit of the present invention; Wherein 2 (a) is the input signal and decision level in the circuit of the invention, 2 (b) the digital baseband signal Vout of comparator output.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, it is an OOK receiver data separator based on the shift peak detection method. First, the filtered analog baseband signal passes through the shifter to realize the negative shift of the voltage, and then detects the shifted The positive peak value of the signal is used as the judgment level. Finally, the judgment level signal is compared with the analog baseband signal through a comparator to obtain a digital baseband signal, and the extraction of the digital baseband signal is completed. The specific structure includes a shifter, the first rail A rail-to-rail operational transconductance amplifier A1, a first PMOS transistor M1, a first capacitor C1, a first resistor R1, a second rail-to-rail operational transconductance amplifier A2, and a second resistor R2.

The shifter includes a third rail-to-rail operational transconductance amplifier A3, a second P-type metal oxide transistor M2, a third resistor R3 and a first current source I1, and the baseband input signal Vin is connected to the third rail-to-rail operational transconductance amplifier A3. The negative input terminal of the conductance amplifier A3, the output terminal of the third rail-to-rail operational transconductance amplifier A3 is connected to the gate of the second PMOS transistor M2, and the source of the second PMOS transistor M2 is connected to the power supply voltage, the drain of the second P-type metal oxide transistor M2 is connected to one end of the third resistor R3, and fed back to the positive input end of the third rail-to-rail operational transconductance amplifier A3, and the other end of the third resistor R3 is connected to the first A current source I1 also serves as the output terminal Vf of the shifter.

The output terminal Vf of the shifter is connected to the negative input terminal of the first rail-to-rail operational transconductance amplifier A1, one end of the first capacitor C1 and one end of the first resistor R1 are both grounded, the other end of the first capacitor C1, the first resistor R1 The other end of R1 and the drain of the first P-type metal oxide transistor M1 are both connected to the positive input end of the first rail-to-rail operational transconductance amplifier A1, and the output end of the first rail-to-rail operational transconductance amplifier A1 is connected to the first rail-to-rail operational transconductance amplifier A1. The gate of a P-type metal oxide transistor M1, the source of the first P-type metal oxide transistor M1 is connected to the power supply voltage; the positive input terminal of the second rail-to-rail operational transconductance amplifier A2 is connected to the baseband input signal Vin, and the first The negative input terminal of the second rail-to-rail operational transconductance amplifier A2 is connected to the drain of the first P-type metal oxide transistor M1, and the second resistor R2 is connected across the positive and negative input terminals of the second rail-to-rail operational transconductance amplifier A2 Between, the output terminal of the second rail-to-rail operational transconductance amplifier A2 is the separated digital baseband signal Vout, and the second resistor R2 is connected across the positive and negative input terminals of the second rail-to-rail operational transconductance amplifier A2 , forming a comparison circuit.

The current value of the first current source I1 is constant, and the required shift voltage value can be obtained by selecting an appropriate resistance value of the third resistor R3. The output signal Vf is different from the input signal Vin by a displacement voltage value, thereby realizing the function of voltage displacement, and the displacement voltage in the circuit of the present invention is 150mV.

The first P-type metal oxide transistor M1, the first capacitor C1 and the first resistor R1 form a feedback charging loop. When the voltage value on the first capacitor C1 is smaller than the voltage value of the output signal of the shifter, the first The P-type metal oxide transistor M1 charges the first capacitor C1; when the voltage on the first capacitor C1 is greater than the voltage value of the output signal of the shifter, the first capacitor C1 needs to be discharged, but because it is connected in parallel with the first capacitor C1 The resistance value of the first resistor R1 is large, and the discharge is very slow. In this way, after a certain period of time, the voltage across the first capacitor C1 stabilizes to a constant value, which is the peak value of the shifted signal, which is used as the decision level Vc for the comparator in the present invention. In Fig. 2(a), the basic working principle of the peak detection of the present invention can be clearly seen, wherein the square wave with any duty cycle is the input waveform of the shift data separator, and the other waveform is the voltage value at both ends of the capacitor, Finally, the stable waveform is the peak level of the shifted signal, which is the decision level. Connect the initial input signal and the decision level to the positive and negative input terminals of the second rail-to-rail operational transconductance amplifier A2 to form a comparator circuit for comparison. When the input signal is greater than the judgment level, the output is high level, which is 1 in the digital signal; when the input signal is lower than the judgment level, the output is low level, which is 0 in the digital signal. Finally, the output of the second rail-to-rail operational transconductance amplifier A2 is the separated digital baseband signal Vout.

Figure 2 shows the received digital signal sequence represented by a square wave signal with an arbitrary duty ratio of -65dBm, and Figure 2 (a) in the figure shows the input signal Vin of the shift data separator in the invention and the voltage at both ends of the first capacitor C1 The voltage Vc is the decision level in the circuit of the present invention. Figure 2(b) is the digital baseband signal Vout output by the comparator. From this figure, we can clearly see the working process of the peak detection of the present invention, the judgment level is the level after the peak value of the input signal is shifted by 150mV, and it can be seen that the present invention can also be very accurate for signals with smaller signal amplitudes. It must be detected, which embodies the characteristics of high sensitivity of the present invention.

The present invention improves the generation method of the judgment level; in addition, the present invention obtains the judgment level by detecting the shifted signal, and the level shift in the traditional structure realizes that the voltage value is the conduction voltage of the diode through a diode. The amount of voltage drop, the value is usually 0.6 ~ 0.7V, the shifted voltage value is relatively large, which is not conducive to obtaining an effective decision level. Moreover, diodes are not easy to implement in CMOS technology. If diodes are used, the integration level is relatively low, and the requirements for power supply voltage are relatively large. In the present invention, through the design of the shifter, a voltage shift of 150mV is realized, and the value of the voltage can be adjusted arbitrarily in practical applications, so the scope of application is relatively wide. The present invention improves the method for generating the judgment level by peak detection. First, the level shift operation is performed on the detection signal, and then the peak detection is performed. The result of the peak detection is used as the judgment level of the comparator, so that the comparator sensitivity and demodulation signal There can be a compromise between the dynamic range of the design.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (1)

1. A kind of OOK receiver data splitter based on shift peak detection method, OOK receiver data splitter is the receiver splitter of switch key control amplitude modulation system; It is characterized in that: first make the analog baseband signal after filtering pass through shift Bit device to realize the negative shift of the voltage, and then detect the positive peak value of the shifted signal as a decision level signal, and finally compare the decision level signal with the analog baseband signal through a comparator to obtain a digital baseband Signal, the extraction of the digital baseband signal is completed, the specific structure of the OOK receiver data separator includes a shifter, the first rail-to-rail operational transconductance amplifier A1, the first P-type metal oxide transistor M1, the first capacitor C1, the first A resistor R1, a second rail-to-rail operational transconductance amplifier A2 and a second resistor R2; The baseband input signal Vin is connected to the input terminal of the shifter, the output terminal Vf of the shifter is connected to the negative input terminal of the first rail-to-rail operational transconductance amplifier A1, one terminal of the first capacitor C1 and one terminal of the first resistor R1 are all grounded, the other end of the first capacitor C1, the other end of the first resistor R1 and the drain of the first P-type metal oxide transistor M1 are all connected to the positive input end of the first rail-to-rail operational transconductance amplifier A1, and the first The output terminal of the rail-to-rail operational transconductance amplifier A1 is connected to the gate of the first P-type metal oxide transistor M1, and the source of the first P-type metal oxide transistor M1 is connected to the power supply voltage; the second rail-to-rail operational transconductance The positive input terminal of the amplifier A2 is connected to the baseband input signal Vin, the negative input terminal of the second rail-to-rail operational transconductance amplifier A2 is connected to the drain of the first P-type metal oxide transistor M1, and the second resistor R2 is connected across the Between the positive and negative input terminals of the two rail-to-rail operational transconductance amplifiers A2, the output terminal of the second rail-to-rail operational transconductance amplifier A2 is the separated digital baseband signal Vout; The shifter includes a third rail-to-rail operational transconductance amplifier A3, a second P-type metal oxide transistor M2, a third resistor R3 and a first current source I1, and the baseband input signal Vin is connected to the third rail-to-rail operational transconductance amplifier A3. The negative input terminal of the transconductance amplifier A3, the output terminal of the third rail-to-rail operational transconductance amplifier A3 is connected to the gate of the second PMOS transistor M2, and the source terminal of the second PMOS transistor M2 is connected to power supply voltage, the drain of the second P-type metal oxide transistor M2 is connected to one end of the third resistor R3, and fed back to the positive input end of the third rail-to-rail operational transconductance amplifier A3, and the other end of the third resistor R3 is connected to The first current source I1 also serves as the output terminal Vf of the shifter.