阅读说明：本技术 一种包络恢复电路 (Envelope restoration circuit ) 是由 马华 邰晓鹏 王小宁 张永欢 于 2020-11-17 设计创作，主要内容包括：本专利提出了一种包络恢复电路,该电路主要应用于负载调制(包括AM和ASK)信号的解调,能够滤除负载调制信号(AM)的载波,恢复信号的包络。该电路主要包括：整流电路(101)和滤波电路(103)构成。整流电路(101)通过整流,使得调幅信号载波的高电平通过,载波的低电平隔离。滤波电路(103)滤除载波,使得恢复的包络信号纹波减小。隔离二极管(102)和隔离二极管(104)具有隔离作用,使得后续滤波电路中间节点信号不会对隔离二极管的输入信号产生反向干扰。(The patent provides an envelope restoration circuit, which is mainly applied to demodulation of load modulation (including AM and ASK) signals, can filter carrier waves of the load modulation signals (AM) and restore the envelopes of the signals. The circuit mainly comprises: a rectifier circuit (101) and a filter circuit (103). The rectification circuit (101) enables high level of an amplitude modulation signal carrier to pass through and low level of the carrier to be isolated through rectification. The filter circuit (103) filters out the carrier so that the recovered envelope signal ripple is reduced. The isolation diode (102) and the isolation diode (104) have an isolation function, so that the intermediate node signal of the subsequent filter circuit does not generate reverse interference on the input signal of the isolation diode.)

1. An envelope restoration circuit for AM load modulation and ASK amplitude shift keying signal envelope restoration is characterized by comprising a rectifying circuit (101) and a filtering circuit (103), wherein an input amplitude modulation signal Vsin is input from one end of the rectifying circuit (101), the other end of the rectifying circuit (101) is connected with one end of the filtering circuit (103), and the other end of the filtering circuit (103) outputs an envelope restoration signal.

2. An envelope restoration circuit as claimed in claim 1, wherein said rectifying circuit (101) comprises: an isolation diode (102), a resistor R0 in parallel to ground, and a capacitor C0, wherein: the P pole of the isolation diode (102) is connected with the input amplitude modulation signal Vsin, the N pole of the isolation diode (102) is connected with the other end of the resistor R0 and the capacitor C0 which are connected in parallel to the ground, and the N pole of the isolation diode (102) is connected with the filter circuit (103).

3. An envelope restoration circuit as claimed in claim 1, wherein the filter circuit (103) comprises: an isolation diode (104), a resistor R1 and a capacitor C1 connected in parallel to ground, a series resistor R2 and a filter capacitor C2 to ground, wherein: the P pole of the isolation diode (104) is connected with the N pole of the isolation diode (102) in the rectifying circuit (101), the N pole of the isolation diode (104) is connected with the resistor R1 connected in parallel to the ground, the other end of the capacitor C1 and one end of the series resistor R2, the other end of the series resistor R2 is connected with the other end of the filter capacitor C2 to the ground in series, and the output signal Vsout is located at the series node of the series resistor R2 and the filter capacitor C2 to the ground.

4. An envelope restoration circuit as claimed in claim 1, wherein the isolation diode (102) is implemented as a diode device, a PMOS transistor device, an NMOS transistor.

5. An envelope restoration circuit as claimed in claim 1, wherein the isolation diode (104) is implemented as a diode device, a PMOS transistor device, an NMOS transistor.

6. An envelope restoration circuit as claimed in claim 1, wherein said rectifying circuit is a cascade of n rectifying circuits (101), n being equal to or greater than 1.

7. An envelope restoration circuit as claimed in claim 1, wherein the filter circuit is a cascade of m filter circuits (103), m being equal to or greater than 1.

8. An envelope restoration circuit as claimed in claim 1, wherein said filter circuit is formed by any of a plurality of rectifier circuits (101) or filter circuits (103) in a hybrid cascade.

9. An envelope restoration circuit as claimed in claim 1, wherein said rectifying circuit may be a hybrid cascade of any plurality of rectifying circuits (101) or filtering circuits (103).

Technical Field

Envelope detection is a signal demodulation technique and method commonly used in the communication field. The envelope restoration circuit is one of the keys in the design of the envelope detection circuit. The invention adopts a novel envelope restoration circuit, and can be generally applied to the design of an envelope detection circuit or the design of a filter circuit.

Background

The communication by using the load modulation mode has wide application, and the envelope detection is a common method for demodulating the load modulation signal. For example, the ISO/IEC 14443 protocol uses a load modulation method for communication, and infrared data (IRDA), laser communication, etc. also use an Amplitude Shift Keying (ASK) method for communication.

The envelope restoration circuit is a core circuit of the envelope detection circuit, and a commonly used envelope detection signal is shown in fig. 1. In fig. 1, the input amplitude modulation signal Vsin is a load modulation AM signal (or amplitude shift keying ASK signal), and the output signal Vsout is an envelope restoration signal; the diode D2 has a rectifying function, and the resistors R3 and R4 and the capacitors C3 and C4 form a low-pass filter circuit.

However, when the carrier frequency is comparable to the signal bandwidth, the conventional envelope restoration circuit generates a large signal distortion of the envelope restoration circuit, and in some cases, the signal distortion of the envelope restoration circuit is large enough to cause difficulty in subsequent demodulation or even failure in demodulation.

Aiming at reducing the distortion of an envelope recovery signal and ensuring the successful demodulation, the improvement of the low-pass filtering performance in an envelope recovery circuit is a key solution, and the patent provides a novel envelope recovery circuit.

Disclosure of Invention

In order to reduce the distortion of the envelope restoration signal, the subsequent low-pass filtering design is the key after the input amplitude modulation signal is rectified. One typical envelope restoration novel circuit proposed by this patent is shown in fig. 2. The function of the novel envelope restoration circuit is to input a signal amplitude modulation signal Vsin and output an envelope restoration signal Vsout.

This novel circuit mainly includes: a rectifier circuit (101) and a filter circuit (103). The rectification circuit (101) enables high level of an amplitude modulation signal carrier to pass through and low level of the carrier to be isolated through rectification. The filter circuit (103) filters out the carrier so that the recovered envelope signal ripple is reduced. The isolation diode (102) and the isolation diode (104) have an isolation function, so that the intermediate node signal of the subsequent filter circuit does not generate reverse interference on the input signal of the isolation diode.

Compared with the conventional envelope restoration circuit shown in fig. 1, the isolation diode 104 is a key in the design of the novel envelope restoration circuit (shown in fig. 2). The response characteristics to the input and output signals comparing fig. 1 and 2 are shown in table 1.

TABLE 1 comparison table of input/output response characteristics of circuit with traditional structure and novel structure

As can be seen from table 1, if R1 ═ R3, C1 ═ C3, R2 ═ R4, and C2 ═ C4 in the conventional circuit and the novel circuit, but because a resistor R0 and a capacitor C0 are added in the novel circuit, the carrier filtering cutoff frequency is larger, the carrier ripple of the envelope restoration signal is smaller, and thus the distortion of the output envelope restoration signal is smaller. On the contrary, if the carrier filtering cut-off frequency of the traditional circuit is the same as that of the novel circuit by adjusting the resistance-capacitance parameters, the response speed of the novel circuit to the rising edge and the falling edge of the envelope signal can be ensured to be faster, and the distortion of the envelope recovery signal output by the novel circuit is smaller.

Drawings

Fig. 1 a conventional envelope restoration circuit

FIG. 2 is a typical envelope restoration novel circuit

FIG. 3 PMOS transistor implementing an isolation diode

FIG. 4 NMOS transistor implementing an isolation diode

FIG. 5 is an example of a multi-rectifier circuit cascaded envelope restoration circuit

FIG. 6 is an example of a multi-filter circuit cascaded envelope restoration circuit

FIG. 7 an example of a hybrid cascaded envelope restoration circuit for a rectifier circuit filter circuit

Detailed Description

The novel circuit capable of realizing the fidelity of an envelope restoration signal mainly comprises: a rectifier circuit (101) and a filter circuit (103). The rectification circuit (101) enables high level of an amplitude modulation signal carrier to pass through and low level of the carrier to be isolated through rectification. The filter circuit (103) filters out the carrier so that the recovered envelope signal ripple is reduced. The isolation diode (102) and the isolation diode (104) have an isolation function, so that the intermediate node signal of the subsequent filter circuit does not generate reverse interference on the input signal of the isolation diode.

The rectifier circuit (101) is shown in fig. 2, and the circuit thereof is configured as follows: the amplitude modulation signal Vsin is input from the P pole of the diode D0(102), and the rectified signal is output from the N pole of the diode D0; the N pole of the diode P0 is connected with a node together with the resistor R0 and the capacitor C0, and the other ends of the resistor R0 and the capacitor C0 are simultaneously grounded.

The rectifier circuit (103) is shown in fig. 2, and its circuit is constituted by: an input signal is input from a P pole of the diode D1(104), and an N pole of the diode D1 is connected with a node together with the resistor R1, the capacitor C1 and the resistor R2; the other ends of the resistor R1 and the capacitor C1 are simultaneously grounded; the other end of the resistor R2 is connected to one end of a capacitor C2, which is also the output node of the envelope restoration signal Vsout; the other end of the capacitor C2 is grounded. The isolation diodes (D0 and D1 in fig. 2) can be implemented by normal diodes, by a PMOS transistor circuit connection method as shown in fig. 3, or by an NMOS transistor connection method as shown in fig. 4.

The rectifying circuit (101) and the filtering circuit (103) can be regarded as basic units, and a new envelope restoration circuit is formed through different cascade combination. Such as: an envelope restoration circuit formed by cascading three rectifying circuits (101) is shown in FIG. 5; an envelope restoration circuit in which two filter circuits (103) are cascaded is shown in fig. 6; two rectifying circuits (101) and one filtering circuit (103) are mixed and cascaded as shown in fig. 7. And protect these as claim terms.

The above description is only exemplary of the present invention and should not be construed as limiting the present invention, and any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.