KR950002440B1 - Ascilation frequency compensating method of the vcd - Google Patents

Abstract

The method for compensating an oscillation characteristic variation and a modulated freq. variation generated by the temperature variation, includes the steps of controlling a PLL circuit(16) by using a processor(17) to select and fix an oscillation freq. voltage through a first detector(14) to store the voltage data in a memory of the processor, detecting the osc. freq. voltage through a second detector(15), comparing the initial osc. freq. voltage with the osc. freq. voltage, and feeding-back the osc. freq. voltage difference through a feedback circuit(18), in case of the difference being larger than the tolerance, to compensate the osc. freq.

Description

Oscillation frequency compensation method of voltage controlled oscillator

1 is a block diagram of a circuit for explaining oscillation frequency compensation in a voltage controlled oscillator according to the present invention.

2 is a flowchart illustrating a process of an oscillation frequency compensation method according to FIG.

* Explanation of symbols for main parts of the drawings

10: voltage controlled oscillator 11: oscillation circuit

12: control stage 13: oscillation signal output stage

14: first detection circuit 15: second detection circuit

16: PLL circuit 17: processor

18: feedback circuit

The present invention relates to a wireless communication device, and more particularly, to a method of compensating oscillation characteristic change and modulation frequency shift caused by oscillation frequency voltage output from a voltage controlled oscillator having a frequency modulation function according to temperature change.

In the case of the voltage controlled oscillator, the most influential effect on the frequency characteristics is the coil component of the oscillator circuit, which changes the inductance according to the temperature change, which affects the oscillation frequency of the circuit. Conventionally, in order to compensate for the characteristics caused by the temperature change, parts having very good temperature characteristics are used, or other components used in the peripheral circuit of the voltage controlled oscillator are used to have components having characteristics opposite to those of the components in the oscillator. Compensation effect was obtained by using.

In the conventional temperature compensation method, the compensation for the characteristic change is obtained by considering the components constituting the device, so that the characteristics of the circuit are limited according to the characteristic limit values of the components, and such as setting parts of a special standard. There was a problem of difficulty in production and cost increase.

The present invention has been devised in view of this point, and the temperature corresponds to the coil component in the oscillation circuit when the temperature rises as the temperature coefficient has positive (+) or negative (-) characteristics according to the characteristics of the component in use of the wireless communication device. When the inductance is increased, the oscillation frequency is lowered. On the contrary, when the temperature is lowered, the oscillation frequency is increased, so that the oscillation frequency that changes with temperature is kept constant, so that the device operates stably and compensates for the frequency shift of the modulated signal. The purpose is to provide a method for this.

In order to achieve the above object, the present invention provides a wireless communication device, when the operating power is applied, the processor controls the PLL circuit to select and fix the oscillation frequency of the voltage controlled oscillator, and the voltage control after performing the first step. A second step of detecting an initial oscillation frequency voltage output from the oscillator through a first detection circuit and storing it in a memory means of the processor; and after performing the second step, the processor generates an oscillation frequency through a second detection circuit at predetermined time intervals. A third step of detecting a voltage, an oscillation frequency compared in a fourth step and a fourth step of comparing an initial oscillation frequency voltage stored in the second step with an oscillation frequency voltage detected at a predetermined time interval in the third step If the difference in voltage is greater than the allowable voltage change value of the processor, the corresponding oscillation frequency voltage difference And a fifth step of compensating for the oscillation frequency by adjusting the oscillation level of the control stage by feeding back through the oscillation frequency.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a circuit for explaining temperature compensation in a voltage controlled oscillator having a modulation function according to the present invention, and FIG. 2 is a flowchart for explaining a temperature compensation method according to FIG.

As can be seen in FIG. 1, the present invention provides a voltage controlled oscillator 10, a first detection circuit 14, a second detection circuit 15, a PLL circuit 16, a processor 17, and a feedback circuit. 18. The voltage controlled oscillator 10 includes an oscillation circuit 11 for generating a frequency signal of a predetermined band and an oscillation signal output stage 13 for processing and outputting a frequency signal applied from the oscillation circuit 11. And a control stage 12 for applying a predetermined control signal for compensating the oscillation frequency level to the oscillation circuit 11 side according to the signal applied to the oscillation circuit in order to compensate for the deviation of the oscillated output frequency signal. . The PLL circuit 16 applies a phase locked signal for generating a fixed frequency signal of a predetermined band to the oscillation circuit 11 side of the voltage controlled oscillator 10 when power is supplied to the apparatus and enters an operating state. The first detection circuit 14 detects an oscillation frequency of a predetermined band occurring with a predetermined period. The second detection circuit 15 detects an oscillation frequency signal of a predetermined band generated at a predetermined time interval with a predetermined period. The processor 17 stores and compares the voltage values of the detected oscillation frequency signals applied from the first detection circuit 14 and the second detection circuit 15 and controls the overall operation of the frequency signal voltage controlled oscillation. The feedback circuit 18 feeds back the voltage difference of the oscillation frequency signal detected by the first detection circuit 14 and the second detection circuit 15 to compensate the control of the control stage 12 in the voltage controlled oscillator 10. Is applied as a signal.

The operation of the present invention configured with the above functions will be described with the second diagram as follows.

When power is supplied to the apparatus and enters the operating state, the processor 17 applies a control signal to the PLL circuit 16 to select and generate a frequency signal of a predetermined band. The PLL circuit 16 is set so as to oscillate only a frequency signal phase-locked in a predetermined band on the oscillation circuit 1 side in the voltage controlled oscillator 10 in accordance with the control signal applied. At this time, the fixed frequency signal oscillated from the oscillation circuit 11 is output to the oscillation signal output terminal 13, and after the output level is adjusted, the initial oscillation frequency voltage V _LO is detected and the memory means of the processor 17. Is set to. On the other hand, the second detection circuit 15 detects the oscillation frequency voltage applied from the oscillation signal output terminal 13 of the voltage controlled oscillator 10 at predetermined time intervals according to the control signal of the processor 17 to be the processor 17. The processor 17 compares the initial oscillation frequency voltage V _LO detected by the first detection circuit 14 and set in the memory means with the oscillation frequency voltage detected by the second detection circuit 15 at predetermined time intervals. Since the processor 17 stores the minimum voltage conversion value V _{TH that} is allowed by the device itself according to the characteristics of the circuit designed by the user and the voltage used, the processor 17 detects it through the first detection circuit 14 and stores the memory means. The minimum voltage conversion value (V _TH ) allowed by the processor 17 is a comparison value | Δ | of the initial oscillation frequency voltage set in step S and the oscillation frequency voltage detected at predetermined time intervals through the second detection circuit 14. ), The comparison voltage value | Δ | is fed back to the control terminal 12 of the voltage controlled oscillator 10 through the feedback circuit 18 so that the control stage 12 corresponds to the comparison voltage value | Δ |. Since the oscillation frequency is compensated, the oscillation circuit 11 is controlled.

That is, when the temperature rises, the inductance value corresponding to the coil component in the oscillation circuit 11 increases, so that the oscillation frequency f _LT is lowered, which is then synchronized to the initial fixed oscillation frequency f _LO '. In order to reduce the capacitance of the peripheral circuit, the output level is adjusted at the varistor provided in the oscillation signal output terminal 13 connected to the oscillation circuit 11 so that the oscillation frequency voltage is increased. Therefore, in order to compensate for the difference between the increased oscillation frequency voltage V _LT and the initial oscillation frequency voltage V _LO , the difference between the initial oscillation frequency voltage V _LO and the changed oscillation frequency voltage is provided in the control stage 12. The selector is adjusted and fed back to the reverse operating voltage, thereby lowering the capacitance value of the oscillation circuit 11. As a result, the frequency of the oscillation circuit 11 is increased again, so that the oscillation frequency voltage V _LT from the oscillation signal output terminal 13 is lowered.

As such, the difference between the oscillation frequency voltage V _LT at the oscillation signal output terminal 13 and the oscillation frequency voltage V _LO initially fixed is detected and the voltage corresponding to the difference is stored in the control stage 12. By repeating the process of returning the varactor to reverse operation, the oscillation circuit 11 is adjusted closer to the initial oscillation frequency, thereby compensating for the variation of the oscillation frequency of the circuit due to temperature or other environmental changes. In addition, when the temperature decreases, the inductance value of the oscillation circuit 11 is lowered, so that the oscillation frequency f _LT is increased, so that the capacitance of the peripheral circuit is adjusted to match the initial oscillation frequency f _LO of the circuit. Since the value needs to be increased, the output level of the varistor provided in the oscillation signal output terminal 13 is adjusted to lower the oscillation frequency voltage. In order to keep the lowered oscillation frequency voltage constant, the oscillation frequency voltage is kept constant by repeating the same process when the temperature rises.

As described above, the oscillation frequency, which changes as the temperature changes, is kept constant, making stable operation in the circuit and compensating for the frequency variation of the modulation signal.

Claims (1)

In a wireless communication device, when an operating power is applied, the processor controls a PLL circuit to select and fix an oscillation frequency of a voltage controlled oscillator, and to perform an initial oscillation frequency voltage output from the voltage controlled oscillator after performing the first stage. A second step of detecting through the first detection circuit and storing the result in a memory means of the processor, and after performing the second step, the processor detects the oscillation frequency voltage through the second detection circuit at predetermined time intervals; The difference between the oscillation frequency voltages compared in the fourth step and the fourth step comparing the initial oscillation frequency voltage stored in the second step and the oscillation frequency voltage detected at predetermined time intervals in the third step is the allowable voltage change value of the processor. If larger, the oscillation frequency voltage difference is fed back through the feedback circuit to adjust the oscillation level of the control stage. Oscillation frequency compensation method of the voltage-controlled oscillator comprising: a fifth step of compensating the oscillation frequency.