JPH0584880U - Linearizer for temperature compensation - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a linearizer for temperature correction which has a simple circuit configuration and is easy to adjust. [Structure] The 0-th power circuit (15) generates a constant signal. The 1st to n-th power circuits (16-1 to 16-n) respectively output the 1st to n-th power signals from the 1st power to the nth power. The coefficient storage circuit (13) stores in advance what kind of coefficient is given to at least one of the constant signal and the first to nth power signals for each ambient temperature detected by the temperature sensor (11). The coefficient data is output according to the ambient temperature detected by the temperature sensor. A D / A conversion circuit (14) adds the coefficient to at least one of the constant signal and the first to nth power signals based on the coefficient data to add at least one of the 0th to nth processed signals. Output one. Adder circuit (17)
Outputs the corrected curve corresponding to the detected ambient temperature by adding the output signals of the 0th to nth processing signals, and outputs the corrected voltage based on the corrected curve.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a temperature compensating linearizer for compensating and outputting an input voltage according to ambient temperature, and particularly in an FM-CW (Frequency Modulated Continuous Wave) radar, the linearity of frequency modulation characteristics is changed to ambient temperature change. For linearizers to compensate accordingly.

[0002]

[Prior Art]

 In the frequency modulation circuit in the FM-CW radar, since the frequency characteristic of the VCO (voltage controlled oscillator) used therein is affected by the ambient temperature, the frequency modulation characteristic also loses its linearity due to the change in the ambient temperature. Therefore, a linearizer is used to correct the linearity of the frequency modulation characteristic according to the ambient temperature. Conventional linearizers are designed to form one ideal correction curve for a certain ambient temperature or a certain range, that is, the ambient temperature within a range where the frequency modulation characteristics do not differ so much. It has a memory for the formation of the ideal correction curve.

As a method of creating a correction curve, there are a first method of analogically approximating with a polygonal line and a second method of digitally approximating with a stepwise curve of a minute difference. In either method, the shape of the correction curve is determined for each ambient temperature (including the case of ambient temperature within a certain range), and the correction curve is formed based on the data stored in the memory in advance.

FIG. 2 is a block diagram of a linearizer according to the first method, which includes a temperature sensor 21 for detecting an ambient temperature and an A / A for converting a temperature detection signal from the temperature sensor 21 into a digital signal. It includes a D conversion circuit 22 and a data ROM 23 that stores curve forming data for forming a correction curve that differs for each ambient temperature. The D / A conversion circuit 24 represents the offset value (indicating the starting point level of the correction curve) of the correction curve corresponding to the ambient temperature detected by D / A converting the curve forming data from the data ROM 23. Is output to the first to nth offset circuits 25-1 to 25-n, and the second signal representing the slope value of the correction curve (indicating the slope of the correction curve) is output to the first to nth slopes. It outputs to the circuits 26-1 to 26-n.

Here, the correction curve to be created is equally divided into first to n-th regions, and each divided region is approximated by a straight line. The first to the n-th polygonal line circuits 27-1 to 27-n are used. For example, regarding the first divided area of the correction curve (the area on the starting end side of the correction curve), the first offset circuit 25-1 outputs the first signal based on the first signal from the D / A conversion circuit 24. The signal indicating the offset value of the divided area, that is, the level of the starting point of the straight line is output, and the first gradient circuit 26-1 outputs the signal of the first divided area based on the second signal from the D / A conversion circuit 24. A signal indicating the slope of the straight line is output. The first polygonal line circuit 27-1 receives the control voltage V _IN of the VCO as an input voltage and receives the first division circuit based on the signals from the first offset circuit 25-1 and the first slope circuit 26-1. A straight line of the area is created and a signal representing this is output to the addition circuit 28. Similarly, each of the second to n-th polygonal line circuits creates a straight line of the second to n-th divided areas and outputs a signal representing each straight line to the adder circuit 28.

The addition circuit 28 synthesizes the straight lines of the first to n-th divided areas supplied from the first to n-th polygonal line circuits 27-1 to 27-n to create a correction curve, and this correction curve Based on this, the control voltage V _IN is corrected and output as the output voltage V _OUT . The control circuit 29 is a circuit for supplying a clock signal and the like to the A / D conversion circuit 22, the data ROM 23, and the D / A conversion circuit 24.

[0007]

[Problems to be solved by the device]

 By the way, in the method of approximating the correction curve by the polygonal line as described above, in order to approximate it to the ideal correction curve as much as possible, a large number of combinations of the offset circuit, the gradient circuit, and the polygonal line circuit are required, and the circuit becomes complicated. However, there is a problem that adjustment is difficult and it takes a long time. On the other hand, the second method, which approximates a stepwise curve, also has a problem that the memory capacity is inevitably increased and the digital noise is not reduced, so that the C / N is deteriorated.

Therefore, an object of the present invention is to provide a temperature correction linearizer having a simple circuit configuration and easy adjustment.

[0009]

[Means for Solving the Problems]

 The linearizer for temperature correction according to the present invention creates a correction curve corresponding to the ambient temperature according to the ambient temperature, corrects the input voltage based on the correction curve, and outputs the corrected linear voltage for detecting the ambient temperature. Temperature sensor, a constant generating circuit for generating a constant signal, and the first to nth power signals to which the input voltage is input and which output first to nth power signals, respectively. The power circuit and the coefficient to be applied to at least one of the constant signal and the first to nth power signals for each ambient temperature detected by the temperature sensor are stored in advance. A coefficient storage circuit that outputs coefficient data according to the ambient temperature detected by the temperature sensor; the constant signal based on the coefficient data; and the first to nth power signals. A signal processing circuit for adding the coefficient to at least one and outputting at least one of the 0th to nth processed signals, and the detected 0th to nth processed signals are added. And an adder circuit that creates the correction curve corresponding to the ambient temperature and outputs the corrected voltage based on the correction curve.

[0010]

[Action]

 In the present invention, a correction curve is approximated by a polynomial curve by a constant generation circuit and n power circuits from the 1st power to the nth power, and the coefficient storage circuit responds to changes in the ambient temperature. By adding different coefficients to the output signals of the constant generation circuit and the n power circuits, different correction curves are created depending on the ambient temperature.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIG. Referring to FIG. 1, the temperature compensating linearizer according to the present invention is similar to a conventional one in that a temperature sensor 11 for detecting an ambient temperature and an A / D conversion circuit 12 for converting a detection signal from the temperature sensor 11 into a digital signal. Have and. The feature of the present invention is that a coefficient storage circuit 13 by a ROM, a D / A conversion circuit 14, a 0-th power circuit 15, a 1st to nth power circuit (in order to allow a correction curve to be approximated by a polynomial curve). Exponentiation circuit) 16-1 to 16-n, an addition circuit 17, and a control circuit 18.

The coefficient storage circuit 13 stores in advance the coefficients to be given to the output signals of the 0th power circuit 15 and the 1st to nth power circuits 16-1 to 16-n for each ambient temperature. This coefficient differs not only for each circuit of the 0th power circuit 15 and the 1st to nth power circuits 16-1 to 16-n, but also for the ambient temperature. In addition, when the correction curve is represented by a polynomial of degree depending on the ambient temperature, the coefficient storage circuit 13 determines that the correction curve for a certain ambient temperature is expressed by a cubic expression, for example. In the table, coefficients for the 0th power circuit 15 and the 1st to 3rd power circuits are stored as coefficient data corresponding to the ambient temperature. Similarly, when it is decided to express another ambient temperature correction curve by a quadratic equation, the 0th power circuit 15, the 1st power circuit 16-1, and the 2nd power circuit are used as coefficient data corresponding to the ambient temperature. Each coefficient for 16-2 is stored. The coefficient data is determined and stored for each ambient temperature. The type of the ambient temperature may be set, for example, by setting a correction curve every 1 degree, but the linearity due to temperature change may be set. In areas where the influence is large, a correction curve is set, for example, every 0.5 degrees, and in areas where there is not much influence even if the temperature changes, for example, one correction curve is used within a change range of 3 to 5 degrees. You can The 0-th power circuit 15 is a circuit for generating a constant, and may be called a constant generation circuit. The 1st to nth power circuits 16-1 to 16-n are for generating the 1st to nth power functions for forming a polynomial, respectively, and in this example, the 1st to nth power circuits 16-1 By cascading 16 to 16-n, each circuit after the squaring circuit 16-2 can generate each function by utilizing the function of the circuit in the preceding stage, thereby simplifying each circuit. ing. The D / A conversion circuit 14 gives a series of coefficients supplied from the coefficient storage circuit 13 to each function from the 0-th power circuit 15, the 1st to nth power circuits 16-1 to 16-n, It may be called a signal processing circuit. The control circuit 18 supplies a clock or the like to the A / D conversion circuit 12, the coefficient storage circuit 13, and the D / A conversion circuit 14 as in the conventional case.

Next, the operation will be described. When the temperature detection signal A / D converted by the A / D conversion circuit 12 is applied to the coefficient storage circuit 13, the coefficient storage circuit 13 responds to the detected ambient temperature. A series of coefficient data for the 0th power circuit 15 and the 1st power circuit to the nth power circuit 16-1 to 16-n are serially output to the D / A conversion circuit 14. On the other hand, the 0th power circuit 15 constantly outputs a signal indicating a constant, and the 1st power circuit 16-1 receives a control voltage V _IN and outputs a signal indicating a function of the 1st power to the squaring circuit 16-2. Outputs a signal indicating a square function based on the output from the square circuit 16-1. Similarly, the third to nth power circuits output signals indicating the third to nth power functions based on the outputs of the preceding stages.

In the D / A conversion circuit 14, the series of coefficient data supplied from the coefficient storage circuit 13 are converted into corresponding functions from the 0th power circuit 15 and the 1st to nth power circuits 16-1 to 16-n, respectively. The coefficients are added as coefficients, and the added functions of 0th power to nth power are output to the addition circuit 17. For example, if the correction curve corresponding to the detected ambient temperature is expressed by a quadratic equation, as described above, the coefficient storage circuit 13 outputs the 0th power circuit 15, the 1st power circuit 16-1, and the 2nd power circuit. Since the coefficients for the circuit 16-2 are output, the D / A conversion circuit 14 also outputs three types of signals with coefficients added to the functions of 0, 1, and 2. The adder circuit 17 synthesizes the inputted 0th to nth power functions to create a correction curve by a polynomial, and corrects the control voltage V _IN based on this correction curve and outputs it as the output voltage V _OUT . The output voltage V _OUT is supplied to VCO in the frequency modulation circuit as a tuning voltage.

As is clear from the above description, the linearizer for temperature correction according to the present invention has a configuration in which the correction curve is created by a polynomial, so that the circuit configuration is simpler than the approximation method using the polygonal line, and the ideal correction is performed. Since the curve can be approximated as much as possible, the linearity of the frequency modulation characteristic can be improved. For example, if the quadratic curve is to be approximated by the polygonal line approximation method as much as possible, several dozen or more combinations of the polygonal line circuit, the offset circuit and the gradient circuit in FIG. One square circuit and two square circuits are sufficient. It is sufficient that the integer n in the present invention is 3 to 4, and the simpler the correction curve, the simpler the circuit configuration.

According to the present invention, further, by synchronizing the data update period of the A / D conversion circuit 12 and the D / A conversion circuit 14 by the control circuit 18 with the frequency modulation period, digital noise is generated as a break in the received signal. It becomes equivalent to the pure analog approximation by driving to, and thereby the C / N of the VCO related to the noise characteristic of the modulation voltage can be suppressed as much as possible.

[0017]

[Effect of the device]

 As described above, the temperature correction linearizer according to the present invention has a configuration in which the correction curve is created by a polynomial equation, so that the correction curve is infinitely approximated to the ideal correction curve and the linearity of the frequency modulation characteristic is improved. In addition, C / N characteristics can be improved by reducing digital noise.

In addition, the adjustment work can be performed easily and in a short time with a simple circuit configuration. Further, the storage capacity of the coefficient storage circuit can be small because it is sufficient to store the coefficient of the polynomial for each ambient temperature.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

V _IN control voltage V _OUT output voltage

Claims (2)

[Scope of utility model registration request] 1. A temperature-correcting linearizer that creates a correction curve corresponding to the ambient temperature according to the ambient temperature and corrects and outputs an input voltage based on the correction curve, and a temperature sensor for detecting the ambient temperature. A constant generation circuit for generating a constant signal; first to nth power circuits which receive the input voltage and output first to nth power signals from the first power to the nth power, respectively; The constant signal for each of the ambient temperatures detected by a temperature sensor, the first to nth
A coefficient storage circuit that stores in advance what coefficient is to be applied to at least one of the power signals, and a coefficient storage circuit that outputs coefficient data according to the ambient temperature detected by the temperature sensor; Based on the above, at least one of the constant signal and the first to nth power signals is used.
Signal processing circuit for adding at least one of the 0th to nth processed signals by adding the coefficient to one, and the detected ambient temperature by adding the output 0th to nth processed signals And a summing circuit that creates the correction curve corresponding to the above and outputs a voltage corrected based on the correction curve. 2. The temperature-correcting linearizer according to claim 1, wherein each of the first to n-th power circuits is a cascade connection of power circuits, and the input voltage is applied to the first power circuit. A linearizer for temperature correction characterized by being input.