KR20000018301A - Device and a method thereof for receiving efficiency and a high dynamic range in a mobile communications terminal device - Google Patents

Abstract

PURPOSE: A device is provided to improve receiving efficiency of interference environments, and maintain a dynamic range in mobile communication terminal devices. CONSTITUTION: A method for improving receiving efficiency and a high dynamic range in mobile communications terminal devices comprises: a low noise amplifier for amplifying a received signal through an antenna; a first controlling section for tracking input power received through the antenna in the normal state; a second controlling section for tracking the extent of interference environments in mobile communications terminal devices. The low noise amplifier makes the current flowing in the low noise amplifier become a low value, when it is the little input power in the normal state, by inputting the first controlling section and the second controlling section. The low noise amplifier controls the current flowing in the low noise amplifier to a high value, when the input power is increased in the normal state, and controls the current flowing in the low noise amplifier to a preset high value in interference environments.

Description

Apparatus and method for improving reception performance and high dynamic range in mobile communication terminal equipment

The present invention relates to a mobile communication system, and more particularly, to an apparatus and a method for improving reception performance in a mobile communication terminal device, maintaining a high dynamic range, and improving reception performance in an interference environment.

The conventional mobile communication terminal processes the received signal in the manner as shown in FIG. Referring to FIG. 1, a signal received by an antenna 101 is passed through a duplexer 102 that separates a transmission / reception signal, and is then applied to a low noise amplifier 103 (hereinafter referred to as “LNA”) 103. In the LNA 103, the signal input to the antenna 101 in a weak state is amplified by an appropriate level to be an optimal signal. The signal passing through the LNA 103 is passed by the bandpass filter 104 only the signal in the reception band and is applied to the mixer 105 for downconversion to the intermediate frequency. The mixer 105 mixes the oscillation signal provided by the local oscillator 106 and the input signal and performs downconversion to an intermediate frequency corresponding to the corresponding channel. The downconverted signal in the mixer 105 is amplified by a predetermined level by the intermediate frequency amplifier 107, and then filtered only by the intermediate frequency filter 108. Then, the intermediate frequency automatic gain control amplifier (IF) AGC AMP "). The IF AGC AMP 109 amplifies or attenuates the input signal to an appropriate level based on the reception gain control signal RX_AGC_ADJ applied from the baseband processor 111, outputs the demodulator 110 to the demodulator 110, and demodulates the input signal.

The specific circuit configuration of the LNA 103 of FIG. 1 is the same as that of FIG. 2. In Fig. 2, capacitors C201 and C202 and inductor L203 are used for input matching, and inductor L205 and capacitor C207 are used for output matching. DC bias is supplied through resistor R204. The low noise amplification transistor TR1 has a base end connected to a node located between the inductor L203 and a capacitor C202, a collector end connected to a common node of the inductor L205 and a capacitor C207, and an emitter end connected to the ground. The unexplained capacitor C206 is for AC blocking to prevent alternating current (AC) from being applied to the power supply VCC.

In FIG. 1, the output level of the IF AGC AMP 109 provided to the demodulator 110 should always be maintained at a constant level. For this purpose, the baseband processor 111 provides an RX_AGC_ADJ signal to the IF AGC AMP 109. The baseband processor 111 lowers the voltage of the RX_AGC_ADJ signal so that the IF AGC AMP 109 has a negative gain when the input power (the output level of the IF AGC AMP 109) is large, and the input power (IF AGC AMP 109). If the output level is small, the voltage of the RX_AGC_ADJ signal is increased so that the IF AGC AMP 109 has a positive gain.

In the case of the LNA 103 shown in FIGS. 1 and 2, the optimum noise matching is performed by using the inductor L023 and the capacitor C201 to achieve low noise amplification. Let it go. At this time, the current flowing through the collector of the transistor TR1 is usually a small value to enable low noise amplification. In more detail, since the LNA 103 used in the mobile communication terminal is an amplifier used in the first stage of the receiver, the system noise index of the entire system is highly dependent on the noise index and gain of the LNA 103. Therefore, in order for the LNA 103 located at the first stage to operate with low noise, very little current flows to the low noise transistor TR1 in the LNA 103.

The low noise amplification transistor TR1 flows less current to obtain the optimum noise figure, but the low noise amplification transistor TR1's IP3 point (3'rd order intercept point) is low, resulting in high power input or signal interference at the receiver. In this case, the low noise amplification transistor TR1 is saturated, resulting in a decrease in reception performance. Herein, the IP3 point will be described with reference to FIG. 6. The input / output power characteristics of the transistor are ideally shown in the form of a curve such as 20, but in practice, the saturation region is shown in the same curve as 10. The point where the curve meets the ideal curve 20 and the curve 30 with the slope of the output power 3 to the input power 3 is the IP3 point. Generally, since the IP3 point is about 10 dB higher than the saturation level of the actual curve 10, Has meaning.

On the contrary, if a large current flows through the low noise amplification transistor TR1 to prevent the degradation of the reception performance in an interference environment, and the IP3 point is increased, the low noise amplification transistor TR1 is saturated or there is no deterioration in the reception performance in the interference environment. There is a disadvantage that the use time of the battery is reduced. Also, if a lot of current flows all the time, the noise figure of the low-noise amplifier transistor TR1 falls and eventually the system noise figure falls.

Accordingly, an object of the present invention is to provide an apparatus and method for improving reception performance in a mobile communication terminal device, maintaining a high dynamic range, and improving reception performance in an interference environment.

Another object of the present invention is to provide an apparatus and a method for improving a reception performance which is in contradiction with a noise amplification characteristic in a mobile communication terminal device.

Another object of the present invention is to provide an apparatus and method for improving a battery usage time of a mobile communication terminal.

In accordance with the above object, the present invention controls the current of the LNA on a case-by-case basis to improve dynamic range (noise amplification characteristic), reception performance and battery life time.

1 is a block diagram of a mobile communication terminal receiver according to the prior art.

FIG. 2 is a detailed circuit diagram of the LNA 103 shown in FIG. 1. FIG.

Figure 3 is a block diagram of a mobile communication terminal receiving unit according to an embodiment of the present invention.

4 is a detailed circuit diagram of the LNA 103 and the LNA control unit 112 shown in FIG.

5A is an RX_AGC_ADJ signal characteristic diagram for received power.

5B is a current characteristic diagram of an LNA with respect to received power.

FIG. 6 is a view for explaining a 3'rd order intercept point (IP3) of a transistor; FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

3 is a block diagram of a mobile communication terminal receiver according to an embodiment of the present invention, and further includes an LNA controller 112 in a block configuration according to the related art. The LNA controller 112 controls the LNA 103 using the RX_AGC_ADJ and the intermodulation distortion signal IMD provided by the baseband processor 111. The reception gain control signal RX_AGC_ADJ is a signal provided from the baseband processor 111 and is generally applied to the IF AGC AMP 109 as shown in FIG. 1. However, in an embodiment of the present invention, the LNA controller 112 as well as the IF AGC AMP 109 is provided. Is also applied. As described above, the RX_AGC_ADJ signal has a low voltage level when the power of the input signal is high and a high voltage level when the power of the input signal is low. Thus, the signal coming into the actual baseband is always at a constant level. The IMD signal is a PDM (Pulse Density Modulation) signal provided by the baseband processor 111 according to an embodiment of the present invention. In fact, the receiver receives not only the channel signal in use but also the signals from other systems and other channels are mixed (meaning an interference environment). That is, the signal-to-noise ratio (Ec / N) is low. In the embodiment of the present invention, the IMD signal is output at the "H" level in such a situation.

3 is a detailed circuit diagram of the LNA 103 and the LNA controller 112 shown in FIG. 3. Referring to FIG. 4, the LNA control unit 112 includes resistors R305 to R309 and transistors TR2 and TR3. The LNA control unit 112 receives the RX_AGC_ADJ signal and the IMD signal provided by the baseband processor 11 to control the LNA 103. LNA 103 of FIG. 4 includes resistors R303 and R304 for setting an appropriate operating point for driving the low noise amplifying transistor TR1 and the low noise amplifying transistor TR1. There is also a capacitor C301 and an inductor L303 for low noise input matching, and an inductor L305 and a capacitor C307 for low noise output matching.

FIG. 5A is a RX_AGC_ADJ signal characteristic diagram for a reception power, and FIG. 5B is a current characteristic diagram of an LNA with respect to a reception power.

Hereinafter, an operation according to an embodiment of the present invention will be described in detail with reference to FIGS. 3, 4, 5A, and b. Operation in accordance with an embodiment of the present invention is divided into a steady state and a state under an interference environment (ie, an IMD environment).

In the normal state, the LNA controller 112 and the LNA 103 operate according to the value of the RX_AGC_ADJ signal provided by the baseband processor 111. Referring to FIG. 5A, it can be seen that the voltage value of the RX_AGC_ADJ signal has a range of, for example, 0.4V to 2.2V and is in inverse proportion to the reception power applied to the receiver.

When the input power input to the receiver in the normal state is small, the baseband processor 111 provides the RX_AGC_ADJ signal in the "H" state, and accordingly, the node 113 of the LNA controller 112 takes about 1.4V to 3V and the transistor TR2 is uneven. Through. When the transistor TR2 is not conducting, the voltages distributed by the resistors R309, R304, and R310 are applied to the base of the low noise amplifying transistor TR1, and the low noise amplifying transistor TR1 is conducted so as to enable low noise amplification, which is a normal mode. Do it. When the input power input to the receiver in the normal state is large, the baseband processor 111 provides the RX_AGC_ADJ signal in the "L" state, and accordingly, the transistor TR2 of the LNA controller 112 becomes conductive. When the transistor TR2 is turned on, the base bias of the low noise amplification transistor TR1 is determined by the resistors R304 and R310 only, which causes a much larger bias than that when the transistor TR2 is turned off, thereby increasing the base current and ultimately the low noise amplifying transistor. Raise the IP3 point of TR1. In this case, even when the receiver has a large input power, the low noise amplification transistor TR1 can operate normally without saturation, thereby increasing the dynamic range in the LNA.

On the other hand, the operation in the interference environment will be described. If the input power of the receiver is large and the RX_AGC_ADJ signal is small and the signal-to-noise ratio (Ec / N) at the baseband at that time is small, the baseband processor 111 assumes that the interference signal is input to the receiver and replaces the IMD signal with "H." " When the IMD signal is "H", the transistor TR3 of the LNA controller 112 is turned on. As a result, the base voltage of the transistor TR2 drops to the ground voltage, thereby fully conducting the transistor TR2. As a result, the base voltage of the low noise amplification transistor TR1 is raised to allow a large current to flow in the LNA. So it has a high dynamic range.

Referring to FIG. 5B, the LNA current (reference numeral 40) in a steady state other than the interference environment (IMD environment) and the LNA current (reference numeral 50) under the interference environment (IMD environment) are shown.

In the solid line 40, which shows the LNA current in a steady state rather than in an interference environment (IMD environment), when the reception power is low, the base current of the low noise amplification transistor TR1 is reduced to reduce the output current to maintain the low noise state. As the value of Rx_AGC_ADJ increases gradually, the collector current increases gradually by increasing the base current applied to the low noise amplification transistor TR1 due to the gradually decreasing voltage of the RX_AGC_ADJ signal. A dotted line 50 representing the LNA current under an interference environment (IMD environment) shows that the transistor TR2 is turned on to operate in the high current mode.

In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the equivalent of claims and claims.

As described above, the present invention varies the current of the low noise amplifier for each situation. When the reception power is large in a normal state, the low noise amplifier current flows a lot to obtain a high dynamic range, and when the reception power is low in the normal state, Low-noise amplifier current flows less, improving low-noise characteristics, improving receiver sensitivity. In addition, the LNA operates in a high current mode to prevent a decrease in reception performance in an interference environment. This method of the present invention can reduce the consumption of the current can increase the use time of the battery and can operate with a high current in the interference environment can improve the performance of the terminal without deteriorating the reception sensitivity.

Claims (4)

In the device for improving the reception performance and high dynamic range in the mobile communication terminal device, A low noise amplifier for low noise amplifying the signal received through the antenna, A controller for performing a first control according to an input power received through the antenna in a steady state and a second control according to an interference environment of the mobile communication terminal device; With the first and second control as inputs, the current flowing to the low noise amplifier becomes a low value at a low input power in a steady state, and if the input power gradually increases in the steady state, the current flowing to the low noise amplifier is gradually increased to a high value. And a low noise amplifier controller for controlling a current flowing through the low noise amplifier to a predetermined high value in an interference environment. The apparatus of claim 1, wherein the first control is a control for an intermediate frequency gain control amplifier, and the second control is a control according to a signal interference degree for the mobile communication terminal. A method for improving reception performance and high dynamic range in a mobile communication terminal having a low noise amplifier at a first stage of a receiver, Determining whether the mobile communication terminal apparatus is an interference environment by using an input power and a signal-to-noise ratio applied to a receiver; Adjusting the current of the low noise amplifier according to the input power received through the antenna in the normal state according to the determination; And controlling the current of the low noise amplifier to a predetermined high current value in the interference environment based on the determination. 4. The method of claim 3, wherein the current flowing to the low noise amplifier becomes a low value when the input power is low in the steady state, and the current flowing to the low noise amplifier is gradually controlled to a high value when the input power gradually increases in the normal state. Characterized by the above.