Circuit for converting low-delay differential signal into single-ended signal

Abstract

The invention discloses a low-delay differential signal-to-single-ended signal circuit, which is applied to differential signal-to-single-ended signal conversion of optical sampling of a laser range finder, and is composed of a transformer chip and two current-limiting resistors, the current-limiting resistors are respectively arranged between the differential signal positive signal connecting end and the differential signal negative signal connecting end and the corresponding connecting pins of the primary side of the transformer chip, and the dotted terminals of the pins, connected with the differential signal negative signal connecting end of the primary side, of the secondary side of the transformer chip are grounded. A dotted terminal of a pin, connected with the primary side differential signal positive signal connecting end, of the secondary side of the transformer chip outputs a single-ended signal. According to the technology, a circuit composed of a transformer chip and two resistors is used, conversion between a differential signal and a single-end signal can be achieved within 5 ns, and fixed errors caused by the conversion between the differential signal and the single-end signal in the distance measuring process are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser ranging, and in particular relates to a low-latency differential signal to single-ended signal conversion circuit. Background Art

[0002] In the field of distance measurement, the accuracy of distance is related to the delay of the circuit. The edge moment of the optical sampling signal is the starting moment of the distance calculation. Generally, the optical sampling signal is a differential signal. The differential signal has a high anti-interference characteristic and can ensure the stability of the calculation start signal. Therefore, the optical sampling signal needs to be input in the form of a differential signal and converted into a single-ended signal for output for subsequent circuit processing. In the prior art, there are three ways of differential to single-ended circuits. The first is a single-stage or multi-stage circuit composed of an operational amplifier and a feedback resistor to realize the output of a differential signal. The conversion time of this model is at the microsecond level; the second is realized by a high-speed optical coupler, and the conversion time of this model is at the hundred nanosecond level; the third is realized by a reverse application differential communication chip, and the conversion time of this model is also at the hundred nanosecond level. All three methods will have a large delay, resulting in the accuracy of the distance measurement not meeting the requirements, and the accuracy needs to be corrected. Therefore, the faster the conversion time of the circuit, the smaller the impact on the distance measurement accuracy, and the accuracy does not need to be corrected.

[0003] The conversion rates of differential-to-single-ended circuits built with existing operational amplifiers, high-speed optocouplers, and differential communication chips are all above 100 nanoseconds, resulting in a fixed error of more than 15m in ranging, which does not meet the requirements of high-precision ranging and requires error compensation. In addition, the circuit requires the use of multiple operational amplifiers combined circuits, which have many circuit components and occupy a large space. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-latency differential signal to single-ended signal conversion circuit. The technology uses a circuit consisting of a transformer chip and two resistors, which can realize the conversion of differential signals and single-ended signals within 5ns, reducing the fixed error caused by this part in the ranging process.

[0005] The present invention achieves this object through the following technical solutions:

[0006] A low-latency differential signal to single-ended signal circuit is applied to the differential signal to single-ended signal conversion of optical sampling of a laser rangefinder. The circuit is composed of a transformer chip and two current-limiting resistors. The current-limiting resistors are respectively arranged between the positive signal connection end and the negative signal connection end of the differential signal and the corresponding connection pins on the primary side of the transformer chip. The same-name end of the pin on the secondary side of the transformer chip connected to the negative signal connection end of the primary side differential signal is grounded, and the same-name end of the pin on the secondary side of the transformer chip connected to the positive signal connection end of the primary side differential signal outputs a single-ended signal.

[0007] Furthermore, the turn ratio between the primary side and the secondary side of the transformer chip is 1:1.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] 1. The conversion speed of differential to single-ended is high and the signal delay is small. The conversion rate of differential to single-ended is within 5ns. The delay within 5ns ensures that the delay of this part is within 0.75m for the error of the entire system, which effectively controls the ranging error and is of great significance to improving the ranging error.

[0010] 2. The circuit is simple and easy to build. The circuit only has 1 chip and 2 resistors. The circuit is simple and takes up little space.

[0011] In summary, the present invention solves the delay error when converting the differential signal to a single-ended signal during the optical sampling process of the laser rangefinder, and the delay error can be reduced to within 5ns. At the same time, the circuit is simplified and miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0013] Figure 1 It is the principle diagram of electromagnetic induction;

[0014] Figure 2 This is a schematic diagram of a differential signal to single-ended signal circuit according to the present invention;

[0015] Figure 3 This is a waveform diagram of converting a differential signal to a single-ended signal according to the present invention. DETAILED DESCRIPTION

[0016] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to be able to fully convey the scope of the present invention to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0017] The present invention applies the principle of electromagnetic induction to achieve nanosecond-level conversion delay of differential signals to electrical signals. Figure 1As shown, when an alternating voltage passes through the primary coil of the transformer, an alternating magnetic field is generated in the iron core. At the same time, since the primary coil and the secondary coil are wound on the same magnetic core, the alternating magnetic field induces an electromotive force in the secondary coil. The present invention realizes low-latency conversion of differential signals to single-ended signals through a small chip transformer.

[0018] According to the working principle of the transformer, the design is as follows Figure 2 Circuit shown:

[0019] The circuit is composed of a transformer U7 and two current limiting resistors R23 and R26. In this embodiment, the transformer U7 is of model TXF453229NF-351.

[0020] Pin 1 of the transformer U7 is connected to the positive terminal XF+ of the differential signal through a circuit R23.

[0021] Pin 6 of the transformer U7 is connected to the negative terminal XF- of the differential signal through a circuit R26.

[0022] Pin 3 of transformer U7 is connected to ground.

[0023] Pin 5 of transformer U7 is connected to the output of the single-ended signal.

[0024] Transformer U7 realizes the isolation and conversion from electrical signal to magnetomotive force and then from magnetomotive force to electrical signal.

[0025] The current limiting resistors R23 and R26 are used to prevent the signal from being directly added to the transformer winding and burning the transformer. When the DC power supply voltage is applied to the primary side of the transformer for a long time, the transformer will show a saturation trend. The saturated transformer is equivalent to a very small resistor, so the primary side of the transformer will heat up severely, and then the heat-conducting transformer will burn out.

[0026] The specific working principle of the circuit is as follows:

[0027] When a positive voltage is applied between XF+ and XF-, a current will be generated from XF+→R23→transformer U7 pin1, transformer U7 pin6→R26→XF-, which will generate a voltage signal between the primary winding of the transformer with 1 pin positive and 6 pin negative. According to the transformer's same-name terminal rule, a voltage spike with 5 pin positive and 3 pin negative will appear on the secondary winding of the transformer (1 pin and 5 pin are same-name terminals). Similarly, when a negative voltage is applied between XF+ and XF-, the inductor between 1 and 6 pins of the transformer will generate a voltage with 1 pin negative and 6 pin positive to resist the drop in current, then a voltage with 5 pin negative and 3 pin positive will appear on the secondary winding of the transformer (1 pin and 5 pin are same-name terminals), which will appear as a negative pulse voltage at the output end. In this way, a differential signal is converted into a single-ended signal. The transformer turn ratio is usually designed as 1:1, so that the voltage at the input pins 1 and 6 is equal to the voltage at the output pins 5 and 3. When a +5V voltage is applied between XF+ / XF-, the primary side of the transformer will also sense a 5V voltage, thus achieving the conversion from a 5V differential to a single-ended 5V voltage signal.

[0028] It is generally believed that the electromagnetic conversion of the transformer is instantaneous, that is, when the input voltage is given to the primary side of the transformer, the secondary side of the transformer will immediately sense the secondary voltage. This method is extremely fast compared to traditional semiconductor devices and fast optocouplers. Through actual testing, this circuit can realize the conversion of differential signals into single-ended signals, and at the same time, the delay can be controlled within 5ns, which is far better than the current conventional circuit design. The differential to single-ended waveform is shown in Figure 3 shown.

[0029] The present invention has been described in detail above through embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The protection scope of the present invention is defined by the claims. Anyone who utilizes the technical solution described in the present invention, or a technician in the field, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and protection scope of the present invention to achieve the above technical effects, or makes equal changes and improvements to the scope of application, shall still belong to the scope of protection covered by the patent of the present invention. It should be noted that in order to make a clear statement, the description of some components and processes that have no direct and obvious connection with the scope of protection of the present invention but are known to those skilled in the art are omitted in the description of the present invention.

Claims

1. A low-latency differential signal to single-ended signal circuit, characterized in that: The circuit is applied to converting the differential signal of optical sampling of a laser rangefinder into a single-ended signal. The circuit is composed of a transformer chip and two current-limiting resistors. The current-limiting resistors are respectively arranged between the positive signal connection end and the negative signal connection end of the differential signal and the corresponding connection pins on the primary side of the transformer chip. The same-name end of the pin on the secondary side of the transformer chip connected to the negative signal connection end of the primary side differential signal is grounded, and the same-name end of the pin on the secondary side of the transformer chip connected to the positive signal connection end of the primary side differential signal outputs a single-ended signal.

2. The low-latency differential signal to single-ended signal circuit according to claim 1, characterized in that: The turn ratio between the primary side and the secondary side of the transformer chip is 1:1.

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