CN1088945C - Signal conditioning device with stable output - Google Patents

Abstract

A signal modulation device with stable output mainly comprises a comparator, an inverter, a digital/analog converter and an up/down counter, wherein the up/down signal output by the comparator is fed back and connected to the digital/analog converter by the connection mode of the inverter, so that the oscillation phenomenon generated by the output signal of the comparator when the output signal of the digital/analog converter is close to the level of the analog input signal of the comparator is avoided, namely the oscillation phenomenon of the up/down signal is eliminated, the accuracy of signal conversion can be improved, and the occurrence of signal errors is reduced.

Description

Signal conditioning device with stable output

The present invention relates to a signal modulation device with stable output, especially a signal modulation device used in counting analog/digital converters or track analog/digital converters to stabilize the output signal without oscillation .

Generally, when a signal modulating device of an analog/digital converter is used, especially for a counting type or a track type analog/digital converter, a comparator and a digital/analog converter are mostly provided inside the converter. Figure 1 shows a commonly used analog/digital converter, which mainly includes a comparator 1, an up/down counter 2 and a digital/analog converter 3, etc., wherein the non-inverting input of the comparator 1 is connected to a Input an analog signal (V _IN ), and the inverting input terminal is connected to the analog signal (V _DAC ) output by the digital/analog converter 3, and then the comparator 1 outputs a rising/falling signal (V _CMP ) to connect In the up/down counter 2, the up/down counter 2 is also connected with a clock signal (clock), which can count the rising/falling signal (V _CMP ) to generate a digital signal output, and the digital signal output is passed through D0, D1, D2 , D3 is connected with the digital/analog converter 3 again. Please refer to Figure 2 for the circuit of the digital/analog converter 3. Figure 2 is a commonly used ladder digital/analog converter, which is widely used in general counting and track analog/digital converters. The ladder digital/analog conversion A circuit composed of resistors R and 2R can convert a digital signal into an analog signal (V _DAC ) for output. However, when the analog signal (V _DAC ) is connected to the non-inverting input of comparator 1 When the level of the analog signal (V _IN ) is close, the rising/falling signal (V _CMP ) will oscillate, please refer to Figure 3a and Figure 3b, which shows the common analog signal (V _DAC ) and the input analog The signal oscillation schematic diagram of signal (V _IN ) level comparison, Figure 3a shows that when the analog signal (V _DAC ) is at high level, and the input analog signal (V _IN ) changes from low level to high level, The period from T ₁ to T ₂ in Figure 3a and Figure 3b means that when the high level of the input analog signal (V _IN ) is close to the high level of the analog signal (V _DAC ) (generally ±5mv- In the range of 20mv), the use of rising/falling signal (V _CMP ) produces unstable oscillation output phenomenon. Figure 3b also shows that when the analog signal (V _DAC ) is at low level, the input analog signal (V _IN ) changes from high level to low level, because the low level of the input analog signal (V _IN ) and The low level of the analog signal (V _DAC ) is close (generally within the range of ±5mv-20mv), which makes the rising/falling signal (V _CMP ) produce unstable oscillation. The oscillation result of these two kinds of signals will cause a serious signal error, making the up/down counter unable to count, and then destroying the signal conversion of the whole circuit, which has a profound impact on the circuit of the converter.

In view of the above-mentioned defects, the present inventor has devoted himself to research and experiments based on many years of research experience, and proposed an invention with reasonable conception, excellent creativity and can effectively improve the above-mentioned defects. Furthermore, the main purpose of the present invention is to provide a signal modulation device capable of eliminating output oscillating noise and having a stable output signal, by changing the feedback technology of the circuit to achieve stable output and improve signal reliability, so as to avoid signal Oscillation occurs.

In order to have a further understanding of the purpose, features and effects of the present invention, now in conjunction with the accompanying drawings the technical solutions of the present invention are described in detail as follows:

Figure 1 is a commonly used analog / digital conversion circuit diagram.

Figure 2 is a commonly used ladder digital / analog converter circuit diagram.

3a and 3b are schematic diagrams of the output signal oscillation of the comparator when the common analog signal is compared with the level of the input analog signal.

Fig. 4 is a circuit diagram of an embodiment of the present invention.

FIG. 5a and FIG. 5b are schematic diagrams of the output signal compared with FIG. 3a and FIG. 3b when comparing the signal operation according to the embodiment of the present invention.

Please refer to Fig. 4, Fig. 4 is the circuit diagram of the embodiment of the present invention, mainly is a signal modulation device 10, and this device comprises a comparator 11, an inverter 12, a digital/analog converter 13 and an up/down Counter 14, wherein the non-inverting input terminal of the comparator 11 is connected to an input analog signal (V _IN ), and the inverting input terminal is connected to the analog signal (V _DAC ) output by the digital/analog converter 13, the comparator The device 11 compares the two analog signals to _generate a rising/falling signal (V _CMP ), which is a status signal output, which can show the relationship between the next analog signal input and the previous analog signal input. Compare as increase or decrease. The rising/falling signal (V _CMP ) is connected to the up/down counter 14 and counted with the clock signal to generate a digital signal output, and the digital signal output is then connected to the digital/analog converter 13, which is mainly a ladder The digital/analog converter 13 is used to convert the digital signal into an analog signal (V _DAC ), and the output is connected to the inverting input terminal of the comparator 11 . On the other hand, the rising/falling signal is connected to the inverter 12, and the inverter 12 is connected to the end of the ladder circuit in the ladder digital/analog converter 13 to be a circuit feedback connection mode, by The feedback method of this circuit can eliminate the signal oscillation phenomenon of the rising/falling signal (V _CMP ), that is, when the analog signal (V _DAC ) is in a high state, and the input analog signal (V _IN ) is switched from a low level When the high level is high and the high levels of the two signals are close to each other, since the rising/falling signal (V _CMP ) reverses the rising/falling signal (V _CMP ) through the inverter 12, the feedback is connected to the digital/analog conversion Signal compensation is performed at the end of the ladder circuit of the comparator 13 to ensure that the rising/falling signal (V _CMP ) output by the comparator 11 is a stable value and avoid signal oscillation.

Please refer to Fig. 5a and Fig. 5b, which are the schematic diagrams of the output signal compared with Fig. 3 when comparing the signal action of the embodiment of the present invention, wherein Fig. 5a shows that the rise/fall signal (V _CMP ) changes from high level to low level, and the analog When the high level of the signal (V _DAC ) is close to the input analog signal (V _IN ), the implementation of the present invention makes the analog signal (V _DAC ) generate a downward displacement voltage (V _of ), which can avoid the rise The /falling signal (V _CMP ) oscillates and becomes unstable. Figure 5b shows that the rise/fall signal (V _CMP ) changes from low level to high level, and the high level of the analog signal (V _DAC ) is close to the input analog signal (V _IN ), which can be implemented by the present invention. Making the analog signal (V _DAC ) generate an upward displacement voltage (V _of ), which can prevent the rising/falling signal (V _CMP ) from oscillating and becoming unstable.

The embodiments of the present invention can effectively solve the phenomenon of signal oscillation in general signal modulation devices by changing the way of circuit feedback, especially when using counting analog/digital converters or track analog/digital converters, etc. It can be shown that embodiments of the present invention ameliorate the disadvantages of conventional devices. Comparing Fig. 3a, Fig. 3b with Fig. 5a, Fig. 5b, it can be clearly observed that the present invention has effectively avoided the unstable state of the output signal of the comparator, and the embodiment of the signal modulation device of the present invention can not only eliminate the signal oscillation phenomenon, but also The increased cost is not much, and does not cause the burden of a large cost increase due to circuit changes.

To sum up, the circuit design of the present invention is not complicated and cumbersome, but the overall circuit operation concept is rich in implementation specificity, which is unprecedented in the market.

Claims (3)

1. one kind has the stable signal changing device of exporting, and this device includes:

One staged digital/analog converter;

One comparator, its non-inverting input connect analog signal input, and reverse input end then connects the analog signal that described digital/analog converter is exported, and two signals are compared to produce a rising/decline signal;

One reverser, its input are connected in this rising/decline signal, and output then is connected in the end of stairing circuit in this digital/analog converter, in order to will rise/the decline signal is reverse;

On one/and following counter, its input has rising/decline signal and clock signal, output digital signal and connect this digital/analog converter after counting.

2. the signal changing device that has stable output according to claim 1, wherein this rising/decline signal is the output of state signal.

3. have the signal changing device of stable output according to claim 1, wherein this signal changing device is a path type analog/digital converter.

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