CN218734263U - Circuit for converting single-end signal into differential signal - Google Patents
Circuit for converting single-end signal into differential signal Download PDFInfo
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- CN218734263U CN218734263U CN202222794912.3U CN202222794912U CN218734263U CN 218734263 U CN218734263 U CN 218734263U CN 202222794912 U CN202222794912 U CN 202222794912U CN 218734263 U CN218734263 U CN 218734263U
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Abstract
The utility model belongs to the technical field of signal conversion, in particular to a circuit for converting a single-end signal into a differential signal, which comprises a reference source, a signal source, an ADC chip, an operational amplifier circuit I and an operational amplifier circuit II; the input cathode end I of the operational amplifier circuit I is used for grounding, a reference source and a signal source are respectively connected to the input anode end I of the operational amplifier circuit I, and the output end I of the operational amplifier circuit I is respectively connected to the input cathode end II of the operational amplifier circuit II and the input anode end III of the ADC chip; and the output end II of the operational amplifier circuit II is connected to the input negative electrode end III of the ADC chip, and the output end III of the ADC chip is connected to the input positive electrode end II of the operational amplifier circuit II. According to the technical scheme, the two operational amplification circuits are fused by using a simple structure, the defect that the common-mode voltage VCM provided by the ADC chip cannot drive the two operational amplification circuits simultaneously is effectively overcome by setting the reference source, the limitation of the first-level operational amplification factor is broken, the stable operation of the circuit can be ensured, and the method has an important significance in realizing high-precision acquisition.
Description
Technical Field
The utility model belongs to the technical field of the signal conversion, especially, relate to a convert single-ended signal into differential signal's circuit.
Background
There are many unbalanced circuit structures in the circuit, and it is often necessary to convert the unbalanced circuit structure into a balanced circuit structure. Unbalanced circuits cause many problems, such as poor electromagnetic compatibility, poor interference rejection, and the like. In contrast, the balanced circuit often has higher electromagnetic compatibility and interference rejection. In the radar design, what is used is that unbalance-to-balance conversion is needed when the analog-to-digital end is converted, the intermediate frequency end is always a single-ended signal, but the intermediate frequency end must be converted into a differential signal before entering the ADC for sampling, not only because the existing high-speed ADC is in a differential input mode, but also the digital circuit at the rear stage can be arranged in a high-speed differential wiring mode, and the anti-interference capability is improved. There are two main types of common single-ended to differential conversion: one is in the form of a balun; the second is in the form of an operational amplifier. The operational amplifier is an active circuit which has an amplification effect on signals, determines that peripheral circuits of the operational amplifier are complex relative to a balun, and is suitable for low-frequency circuits under small signals due to general response of the operational amplifier to high-frequency signals.
The current single-ended to differential conversion circuit is commonly disclosed in chinese patent publication No. CN106505985A, and includes an inverting input terminal, a non-inverting input terminal for receiving a reference signal, and an output terminal; in addition, the first resistor is coupled between the inverting input terminal and the output terminal of the amplifier; the second resistor is coupled to the inverting input end of the amplifier; the third resistor is coupled to the output end of the amplifier; the resistor string is coupled between the output end of the amplifier and the second resistor and comprises a fourth resistor and a fifth resistor which are connected in series. One signal of the pair of differential signals is provided through the third resistor, and the other signal of the pair of differential signals is provided through the resistor string. Such single-ended to differential conversion circuits have the following drawbacks: only one-level operational amplification exists, the amplification factor has limitation, if in order to reach the amplification factor requirement, trade and combine two operational amplifiers, may lead to the circuit extremely complicated, and the common mode voltage VCM that is connected to the collection module of single-ended to differential conversion circuit back-end provides can not drive two-stage operational amplifier simultaneously, (single-ended to differential conversion) circuit can be because of the voltage not enough and the unable steady operation of unable steady operation, the unable steady operation of circuit, finally influences the acquisition precision of signal.
Disclosure of Invention
The utility model discloses to the not enough that above-mentioned prior art exists, provide a circuit that converts single-ended signal into differential signal, adopt the mating reaction of two operational amplifier circuit and ADC chip, utilized simple structure to fuse two operational amplifier circuits to the ADC chip has been solved and the VCM voltage can not drive two operational amplifier's problem simultaneously.
The purpose of the utility model is realized through the following technical scheme:
a circuit for converting a single-ended signal to a differential signal, comprising: the device comprises a reference source, a signal source, an ADC chip, an operational amplifier circuit I and an operational amplifier circuit II; the operational amplifier circuit I is provided with an input positive terminal I, an input negative terminal I and an output terminal I; the operational amplifier circuit II is provided with an input positive terminal II, an input negative terminal II and an output terminal II; the ADC chip is provided with an input positive terminal III, an input negative terminal III and an output terminal III; the input negative electrode end I of the operational amplifier circuit I is used for grounding, the reference source and the signal source are respectively connected to the input positive electrode end I of the operational amplifier circuit I, and the output end I of the operational amplifier circuit I is respectively connected to the input negative electrode end II of the operational amplifier circuit II and the input positive electrode end III of the ADC chip; and the output end II of the operational amplifier circuit II is connected to the input negative electrode end III of the ADC chip, and the output end III of the ADC chip is connected to the input positive electrode end II of the operational amplifier circuit II.
Preferably, the operational amplifier circuit i comprises an operational amplifier i, a resistor R1, a resistor R2, a resistor R3 and a resistor R4; one end of the resistor R1 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R1 is used as an operational amplifier circuit I to be connected with the input positive electrode end I of the signal source; one end of the resistor R2 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R2 is used as the input positive electrode end I of the operational amplifier circuit I connected with the reference source; the output end of the operational amplifier I is used as the output end I of the operational amplifier I, and the output end of the operational amplifier I is connected to the negative electrode of the input end of the operational amplifier I through a resistor R4; one end of the resistor R3 is connected with the negative electrode of the input end of the operational amplifier I, and the other end of the resistor R3 is used as the input negative electrode end I of the operational amplifier circuit I.
Preferably, the operational amplifier circuit ii comprises an operational amplifier ii, a resistor R5, a resistor R6 and a resistor R7; one end of the resistor R5 is connected with the negative pole of the input end of the operational amplifier II, and the other end of the resistor R5 is used as the input negative pole end II of the operational amplifier circuit II; the output end of the operational amplifier II is used as the output end II of the operational amplifier circuit II, and the output end of the operational amplifier II is connected to the negative electrode of the input end of the operational amplifier II through a resistor R6; one end of the resistor R7 is connected with the positive electrode of the input end of the operational amplifier II, and the other end of the resistor R7 is used as the input positive electrode end II of the operational amplifier circuit II.
Preferably, the operational amplifier circuit I and the operational amplifier circuit II are in the same double operational amplifier integrated chip.
Compared with the prior art, the technical scheme has the following advantages:
1) The technical scheme is based on the operational amplifier circuit I, the operational amplifier circuit II and a reference source, an addition circuit and an inverse circuit of signal conversion are formed, basic conditions are provided for single-ended signal conversion differential signals, the voltage of the reference source is provided for the operational amplifier circuit I, and the operational amplifier circuit II is provided with the common-mode voltage VCM by a rear-stage ADC chip.
2) This technical scheme circuit structure is simple, easily realizes, adopts low-cost components and parts to realize, and ADC chip, fortune are put circuit I and are put II three cooperations of circuit to fortune, constitute closed-loop control, combine under the condition of the sufficient voltage that reference source and ADC chip provided for conversion circuit is whole stable.
3) Based on the simple structure of this technical scheme, voltage signal everywhere in the converting circuit has clear relation, can know converting circuit's fault conditions through simple voltage detection, is convenient for maintain and seek the problem point.
Drawings
FIG. 1 is a schematic block diagram of the overall structure of the present invention;
FIG. 2 is a schematic block diagram of the structure of an operational amplifier circuit I;
FIG. 3 is a schematic block diagram of the structure of an operational amplifier circuit II;
FIG. 4 is a schematic diagram of a circuit structure according to an embodiment of the present invention;
in the figure:
1. a reference source; 2. a signal source; 3. an operational amplifier I; 4. and an operational amplifier II.
Detailed Description
The present invention is further described with reference to the following drawings and examples, which should not be construed as limiting the invention to the following examples, and all modifications and improvements of the present invention in the field are intended to be included within the scope of the present invention as claimed.
Example 1
The embodiment provides a circuit for converting a single-end signal into a differential signal (hereinafter, referred to as a conversion circuit), which is a preferred embodiment of the technical scheme and comprises a reference source, a signal source, an ADC chip, an operational amplifier circuit i and an operational amplifier circuit ii; the operational amplifier circuit I is provided with an input positive terminal I, an input negative terminal I and an output terminal I; the operational amplifier circuit II is provided with an input positive terminal II, an input negative terminal II and an output terminal II; the ADC chip is provided with an input positive terminal III, an input negative terminal III and an output terminal III; the input cathode end I of the operational amplifier circuit I is used for grounding, the reference source and the signal source are respectively connected to the input anode end I of the operational amplifier circuit I, and the output end I of the operational amplifier circuit I is respectively connected to the input cathode end II of the operational amplifier circuit II and the input anode end III of the ADC chip; and the output end II of the operational amplifier circuit II is connected to the input negative electrode end III of the ADC chip, and the output end III of the ADC chip is connected to the input positive electrode end II of the operational amplifier circuit II.
Based on the circuit structure, the technical scheme is based on the operational amplifier circuit I, the operational amplifier circuit II and a reference source to form an adding circuit and an inverting circuit for signal conversion, basic conditions are provided for single-ended signal conversion differential signals, the voltage of the reference source is provided for the operational amplifier circuit I, and the operational amplifier circuit II is provided with the common-mode voltage VCM by a rear-stage ADC chip.
This technical scheme circuit structure is simple, easily realizes, adopts low-cost components and parts to realize, and ADC chip, fortune are put circuit I and are put II three cooperations of circuit to fortune, constitute closed-loop control, combine under the condition of the sufficient voltage that reference source and ADC chip provided for conversion circuit is whole stable.
Example 2
As a preferred implementation of the technical solution, in example 1, the operational amplifier circuit i includes an operational amplifier i, a resistor R1, a resistor R2, a resistor R3, and a resistor R4; one end of the resistor R1 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R1 is used as an operational amplifier circuit I to be connected with the input positive electrode end I of the signal source; one end of the resistor R2 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R2 is used as the input positive electrode end I of the operational amplifier circuit I connected with the reference source; the output end of the operational amplifier I is used as the output end I of the operational amplifier I, and the output end of the operational amplifier I is connected to the negative electrode of the input end of the operational amplifier I through a resistor R4; one end of the resistor R3 is connected with the negative electrode of the input end of the operational amplifier I, and the other end of the resistor R3 is used as the input negative electrode end I of the operational amplifier circuit I. The resistor R1, the resistor R2, the resistor R3 and the resistor R4 in the circuit play a role in current limiting protection and balance.
Based on the circuit structure, the voltage input into the operational amplifier circuit I by the reference power supply is Vref, the voltage input into the operational amplifier circuit I by the signal source is Vin, the output voltage of the output end I of the operational amplifier circuit I is Vout1, and the voltages of the positive pole and the negative pole of the input end of the operational amplifier I are V1+ and V1-respectively. The following conditions are further specified: vref = VCM, the resistance of resistor R1 is equal to the resistance of resistor R2, and the resistance of resistor R3 is equal to the resistance of resistor R4. Based on this, there are:
the operational amplifier is known by the deficiency: v1- = V1 +; because of the virtual break, no current flows through the same-direction end of the operational amplifier i, and the currents flowing through the resistor R1 and the resistor R2 are equal, then (Vref-V1 +)/R2 = (V1 + -Vin)/R1, if R1= R2, V1+ = (Vref + Vin)/2 is obtained;
the same applies to the currents flowing through R4 and R3. Then (Vout 1-V1-)/R4 = V1-/R3; if R3= R4; obtaining V1- = Vout1/2;
since V1- = V1+, vout1/2= (Vref + Vin)/2 is obtained, that is, vout1= Vref + Vin. I.e. forming a homodromous addition circuit.
Example 3
As a preferred implementation of the technical solution, in example 2, one end of the resistor R5 is connected to the negative terminal of the input terminal of the operational amplifier ii, and the other end is used as the negative terminal ii of the input terminal of the operational amplifier circuit ii; the output end of the operational amplifier II is used as the output end II of the operational amplifier circuit II, and the output end of the operational amplifier II is connected to the negative electrode of the input end of the operational amplifier II through a resistor R6; one end of the resistor R7 is connected with the positive electrode of the input end of the operational amplifier II, and the other end of the resistor R7 is used as the input positive electrode end II of the operational amplifier circuit II. The resistor R5 and the resistor R6 in the circuit play a role in current limiting protection and balancing, and the resistor R7 plays a role in current limiting protection.
Based on the circuit structure, the voltages of the positive electrode and the negative electrode of the input end of the operational amplifier II are respectively V2+ and V2-, and the output voltage of the output end II of the operational amplifier circuit II is Vout2. Based on this, there are:
the operational amplifier is known by the deficiency: v2- = V2+, VCM = V2+; because the operational amplifier II is broken virtually, almost no current is injected and flows out, the resistor R5 and the resistor R6 are connected in series, and the current flowing through each component in a series circuit is the same, namely the current flowing through the resistor R5 and the current flowing through the resistor R6 are the same; specifically, the current I1 = (Vout 1-V2-)/R5 flowing through R5, and the current I2 = (V2 — Vout 2)/R6 flowing through R6. Because the currents are the same, (Vout 1-V2-)/R5 = (V2-Vout 2)/R6, if R5= R6; vout2=2V2 — Vout1 is obtained; since V2+ = VCM, V2- = V2+, vout2=2 VCM-Vout1 is obtained.
According to the circuit of the operational amplifier circuit II, vout1= Vref + Vin;
and since VCM = Vref;
vout2=2Vref-Vout1 is obtained;
let Vout2=2Vref- (Vref + Vin);
vout2= Vref-Vin;
differential input end signal (Vdiff) = Vout 1-Vout 2 of ADC chip
= Vref+ Vin-( Vref – Vin)
=2 Vin
For slight differences between Vref and VCM, a zero offset calibration can be performed with the ADC chip to eliminate errors between the two.
Based on the relation of the voltage signals, the voltage signals at all places in the conversion circuit are clear, the fault condition of the conversion circuit can be known through simple voltage detection, and the problem point is convenient to maintain and search.
Example 4
As a preferred implementation of the present invention, based on any of the foregoing embodiments, the operational amplifier circuit i and the operational amplifier circuit ii are located in the same dual operational amplifier integrated chip. The dual-operational-amplifier-based integrated chip has the characteristics of high gain, high common-mode rejection ratio, wide common-mode range, simplicity in compensation, stability in working, good temperature stability between the two operational amplifiers and the like, and the performance of the technical scheme can be further improved.
Claims (4)
1. A circuit for converting a single-ended signal to a differential signal, comprising: the device comprises a reference source, a signal source, an ADC chip, an operational amplifier circuit I and an operational amplifier circuit II;
the operational amplifier circuit I is provided with an input positive terminal I, an input negative terminal I and an output terminal I;
the operational amplifier circuit II is provided with an input positive terminal II, an input negative terminal II and an output terminal II;
the ADC chip is provided with an input positive terminal III, an input negative terminal III and an output terminal III;
the input negative electrode end I of the operational amplifier circuit I is used for grounding, the reference source and the signal source are respectively connected to the input positive electrode end I of the operational amplifier circuit I, and the output end I of the operational amplifier circuit I is respectively connected to the input negative electrode end II of the operational amplifier circuit II and the input positive electrode end III of the ADC chip; and the output end II of the operational amplifier circuit II is connected to the input negative electrode end III of the ADC chip, and the output end III of the ADC chip is connected to the input positive electrode end II of the operational amplifier circuit II.
2. A circuit for converting a single-ended signal to a differential signal as recited in claim 1, wherein: the operational amplifier circuit I comprises an operational amplifier I, a resistor R1, a resistor R2, a resistor R3 and a resistor R4;
one end of the resistor R1 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R1 is used as an operational amplifier circuit I to be connected with the input positive electrode end I of the signal source;
one end of the resistor R2 is connected with the positive electrode of the input end of the operational amplifier I, and the other end of the resistor R2 is used as the input positive electrode end I of the operational amplifier circuit I connected with the reference source;
the output end of the operational amplifier I is used as the output end I of the operational amplifier I, and the output end of the operational amplifier I is connected to the negative electrode of the input end of the operational amplifier I through a resistor R4;
one end of the resistor R3 is connected with the negative electrode of the input end of the operational amplifier I, and the other end of the resistor R3 is used as the input negative electrode end I of the operational amplifier circuit I.
3. A circuit for converting a single-ended signal to a differential signal as recited in claim 2, wherein: the operational amplifier circuit II comprises an operational amplifier II, a resistor R5, a resistor R6 and a resistor R7;
one end of the resistor R5 is connected with the negative pole of the input end of the operational amplifier II, and the other end of the resistor R5 is used as the input negative pole end II of the operational amplifier circuit II;
the output end of the operational amplifier II is used as the output end II of the operational amplifier circuit II, and the output end of the operational amplifier II is connected to the negative electrode of the input end of the operational amplifier II through a resistor R6;
one end of the resistor R7 is connected with the positive electrode of the input end of the operational amplifier II, and the other end of the resistor R7 is used as the input positive electrode end II of the operational amplifier circuit II.
4. A circuit for converting a single-ended signal to a differential signal as claimed in any one of claims 1 to 3, wherein: and the operational amplifier circuit I and the operational amplifier circuit II are positioned in the same double operational amplifier integrated chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222794912.3U CN218734263U (en) | 2022-10-24 | 2022-10-24 | Circuit for converting single-end signal into differential signal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222794912.3U CN218734263U (en) | 2022-10-24 | 2022-10-24 | Circuit for converting single-end signal into differential signal |
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| Publication Number | Publication Date |
|---|---|
| CN218734263U true CN218734263U (en) | 2023-03-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222794912.3U Active CN218734263U (en) | 2022-10-24 | 2022-10-24 | Circuit for converting single-end signal into differential signal |
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| Country | Link |
|---|---|
| CN (1) | CN218734263U (en) |
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2022
- 2022-10-24 CN CN202222794912.3U patent/CN218734263U/en active Active
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