KR20010068791A - Apparatus for progressing a imtermodulayion spurious response attenuation(imd) performance in cdma portable radio terminal eqipment - Google Patents

Abstract

PURPOSE: An apparatus for improving the intermodulation characteristics of a CDMA(Code Division Multiple Access) portable radio terminal is provided to reduce the response time for controlling and improve the intermodulation characteristics by controlling an attenuator with an extra hardware device. CONSTITUTION: If a subtractor(230) receives the AGC_CON voltage for controlling the gain of an automatic gain controller(216) lower than a reference voltage, the voltage in inverse proportion to the input is applied in an attenuator(210). The voltage applied in the attenuator(210) is changed the voltage of necessary amount for compensating through a level setter(220). This voltage is applied in the automatic gain controller(216) together the AGC_CON via an adder(224). The attenuated amount is compensated in the adder(224).

Description

Intermodulation characteristic improvement device for code division multiple access portable wireless terminal {APPARATUS FOR PROGRESSING A IMTERMODULAYION SPURIOUS RESPONSE ATTENUATION (IMD) PERFORMANCE IN CDMA PORTABLE RADIO TERMINAL EQIPMENT}

The present invention relates to a technique for receiving performance of a code division multiple access portable wireless terminal, and more particularly, to an apparatus for improving intermodulation characteristics of a code division multiple access portable wireless terminal to solve a problem of deterioration in reception performance due to intermodulation of a received signal. It is about.

In general, the reception signal processing unit of a code division multiple access portable wireless terminal includes a low noise amplifier (LNA), a mixer, and the like, and generates an intermediate frequency (IF) signal through these operations to properly process the received signal. To be done.

However, there may be a case where two continuous waves are input to the low noise amplifier. In this case, the noise component generated by the intermodulated noise component to the output terminal of the low noise amplifier may be input to the reception signal processor. This causes a problem of deterioration of reception performance. The intermodulated noise is mainly generated by the operation of an active element, such as a low noise amplifier or mixer, whose strength typically increases by three times the input power.

Thus, to reduce the effects of such intermodulation, the input voltage must be suppressed. In the prior art, an attenuator was further provided in front of the low noise amplifier, or a means of reducing or bypassing the gain of the low noise amplifier was used.

Accordingly, that is, the internal block configuration of the intermodulation characteristic personality device proposed according to the prior art is as shown in FIG.

1 is a block diagram of an apparatus for improving intermodulation characteristics in a code division multiple access portable wireless terminal according to the prior art.

With reference to this it will be described in detail the problems of the prior art. First, due to the characteristics of the CDMA system, the output (IF) level of the AGC circuit must always be a constant intensity regardless of the intensity of radio waves induced in the antenna. Therefore, the AGC circuit is controlled through the control unit of the terminal. At this time, the level of the voltage controlling the AGC represents the strength of the received radio wave.

If the intensity of the input radio wave is higher than the standard value, the attenuation is proportional to the input intensity through IM_CON. The signal that generates the IM is also reduced as much as the applied attenuation, thereby preventing the degradation of the reception performance due to the IM. At this time, the operating range of the AGC is reduced by the amount of attenuation, so that the strength of the electric field recognized by the controller is different from the strength induced by the actual antenna. To compensate for this, the controller must compensate for the amount of attenuation applied through software processing. In this process, because the software must be processed periodically, the real-time operation is not possible due to the delay, so the open loop power control may not be performed, and at the same time, the load of the software increases, which causes additional problems. .

As a result, in the prior art, the attenuator is adjusted as software of the control unit, which inevitably becomes a periodic control due to the characteristics of the software, and the delay thereof is also a problem.

Accordingly, an object of the present invention is to implement an intermodulation characteristic improving apparatus of a portable wireless terminal which is intended to solve the problem of deterioration of reception performance due to intermodulation of a received signal.

In particular, in the present invention, in order to solve the above problems caused by the software, to control the operation of the attenuator as hardware to implement the intermodulation characteristics improvement apparatus of a portable radio terminal having improved performance.

In order to achieve these objects, in the present invention, a control unit for varying and outputting the automatic gain regulator control voltage according to the strength of a received signal, and outputs in inverse proportion to the control voltage when the automatic gain regulator control voltage is below a predetermined reference voltage. A subtractor for adjusting the attenuation amount of the received and input signal according to the inversely outputted control voltage applied state, a level setter for compensating and outputting the inversely output control voltage to a predetermined level; And an adder for applying to the automatic gain regulator provided as a control voltage according to the addition of the compensated control voltage and the automatic gain regulator control voltage output from the controller.

1 is a block diagram of an apparatus for improving intermodulation characteristics in a code division multiple access portable wireless terminal according to the prior art.

2 is a block diagram of an intermodulation characteristic improving apparatus in a code division multiple access portable wireless terminal according to the present invention;

3 is a detailed circuit diagram of an intermodulation characteristic improving apparatus in the code division multiple access portable wireless terminal shown in FIG. 2;

4 is a graph referred to in describing the operation of the intermodulation characteristic improving apparatus shown in FIG. 3.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, in the following description, many specific details such as components of a specific circuit are shown, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. It is self-evident to those of ordinary knowledge in Esau. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram of an apparatus for improving intermodulation characteristics in a code division multiple access portable wireless terminal according to the present invention.

Referring to this, since the voltage of AGC_CON is controlled by the controller so that the intensity of the intermediate frequency is kept constant, when the voltage falls below the reference voltage, the attenuation signal is input through the subtractor. The voltage applied to the attenuator is made into a suitable form through the level setting section, passes through an adder, and then is applied to the AGC. Since the attenuation is proportional to the input intensity, the intermodulation (IM) characteristic is improved. In addition, since the compensation is performed by using the adder and the level setter, the voltage of the AGC_CON is linearly changed so that the strength of the electric field input from the controller can be accurately determined. As a result, the implementation of the present invention is that the receiver of the CDMA wireless portable terminal configures a hardware control circuit to satisfy the intermodulation (IM) recommendation (IS-98A), thereby stably receiving from the intermodulation (IM) signal. To ensure performance.

3 is a detailed circuit diagram of an intermodulation characteristic improving apparatus in the code division multiple access portable wireless terminal shown in FIG.

Referring to this, in the reception apparatus according to the present invention, a variable attenuator 210, a subtractor 230, an adder 224, and a level setter 220 are further configured in addition to the basic circuit configuration.

Looking at the operation thereof, the intermediate frequency (IF) level should be constant due to the characteristics of the CDMA method, when the signal strength from the antenna is large, the voltage of AGC_CON for gain control of the automatic gain regulator is low, when the signal is small The voltage of AGC_CON becomes high. When AGC_CON equal to or lower than the voltage defined as V_REF is input to the subtractor 230, a voltage inversely proportional to the input is applied to the attenuator 210. The voltage applied to the attenuator 210 is changed to a voltage equal to the necessary compensation while passing through the level setter 220. This voltage is applied to AGC 216 via the adder 224 along with AGC_CON. In addition, since the amount of attenuation is compensated by the adder 224, the AGC_CON is changed without distortion in the change of the electric field.

On the other hand, when the attenuator and AGC is configured as shown in the state (a) in FIG. 4, the operation result according to the embodiment of the present invention can be interpreted by the following method.

First, the attenuation operation is designed when the AGC voltage is between 1.5V and 2V. And since the operating range of AGC can be different according to the design method of the system, it sets the proper operating range according to the system. For example, when the voltage of the AGC becomes 1V-> 1,5V, the voltage of the attenuator 210 is moved from 0-> 3V.

In this state, the subtractor 230 according to the preferred embodiment of the present invention is designed by Equation 1 below.

And, the design of the adder 224 according to a preferred embodiment of the present invention is made by the following equation (2).

Through the above two equations,

Vref, R1, R2, R3, R4, R8, and R9 can be determined.

If each of the predetermined constants comes out as an unachievable value, the constants of the level setters can be changed to produce actual values.

And (b) graph in FIG. 4 shows the control voltage state in each node.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, since the attenuator is adjusted as a separate hardware device, the control response speed is improved, whereby the intermodulation characteristics are satisfactorily met even in a sudden electric field change.

Claims (5)

An apparatus for improving intermodulation characteristics of a wireless terminal having an automatic gain controller for properly adjusting and outputting a gain of a signal received and input as a predetermined control voltage, A controller for varying and outputting the automatic gain controller control voltage according to the strength of a received signal; A subtractor for outputting the control voltage in inverse proportion when the automatic gain regulator control voltage is equal to or less than a predetermined reference voltage; An attenuator for adjusting and outputting an attenuation amount of a signal received and input according to an inversely proportioned output state of a control voltage; A level setter for compensating and outputting the control voltage output in inverse proportion to a predetermined level; And an adder for applying to the automatic gain controller a control voltage according to the addition of the compensated control voltage and the automatic gain regulator control voltage output from the controller. The method of claim 1, wherein the control unit, And when the strength of the received signal is large, increases the automatic gain regulator control voltage, and outputs it, and when the strength of the received signal is small, controls to lower and output the automatic gain regulator control voltage. The method of claim 1, wherein the subtractor, And comparing the input control voltage with a predetermined reference voltage, and outputting the input control voltage as it is or converting the control voltage into an inversely increasing control voltage according to the comparison result. The method of claim 1, wherein the level setting unit, And level converting the control voltage applied to the attenuator to suit the control voltage level of the automatic gain regulator. The method of claim 4, wherein the level setting unit, And a predetermined resistor configured to receive a control voltage applied to the attenuator and to convert the predetermined voltage to a predetermined level.