KR100308901B1 - Receiver for portable radio terminal equipment - Google Patents

Abstract

Code Division Multiple Access (hereinafter referred to as CDMA) type Low noise amplifier can be selected as 1st or 2nd stage by using switching element at the front end of wireless receiver of portable wireless terminal. By selecting the second stage only in the case of ultra weak electric field, the sensitivity is increased to enable a good call.

Description

Receiver of portable wireless terminal {RECEIVER FOR PORTABLE RADIO TERMINAL EQUIPMENT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless transceiver in a portable wireless terminal, and more particularly, to a wireless transceiver having a high sensitivity in an ultra weak electric field.

Dual-mode telephones have a very high probability of error even if the call is disconnected or communicated due to an external interference signal propagated from the analog band. This signal is called InterModulation Distortion (IMD), which affects the CDMA receiver when the CDMA terminal is near the AMPS base station. Strong external interference signals overload the low noise amplifier (LNA) of the CDMA receiver, and the IMD component appears in the CDMA band, causing strong interference. In the end, the call is disconnected.

In general, when the LNA is designed in one stage, the gain of the LNA should be primarily high in order to secure a sensitivity higher than a certain level. But most devices have their own limitations. In addition, even if the sensitivity is improved by improving the front figure by increasing the gain of the front end, single tone distortion is caused by the increase of phase noise due to cross modulation in a single tone. It is difficult to meet the receiver's basic specifications such as IMD due to the increase of the 3rd component of the mixer, mixer and intermediate frequency amplifier. In other words, since it is difficult to trade off between sensitivity, Single Tone Distortion (STD) and IMD, it is difficult to improve the sensitivity at the time of ultra weak electric field.

Accordingly, an object of the present invention is to provide a wireless receiver capable of making a good call by increasing the sensitivity even in an ultra weak electric field in a CDMA portable wireless terminal.

In order to achieve the above object, the present invention enables the LNA to be selected as one or two stages by using a switching element in front of a wireless receiver of a CDMA portable wireless terminal, thereby selecting two stages only when the super weak electric field is used to increase sensitivity. It is characterized in that a high quality call is possible.

1 is a view schematically showing the configuration of a wireless receiver of a portable wireless telephone according to an embodiment of the present invention

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific elements and port names thereof 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 will be obvious to those skilled in the art. 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.

1 is a diagram schematically illustrating a configuration of a wireless receiver of a portable wireless telephone according to an embodiment of the present invention.

The duplexer 11 is connected to the antenna 10 and serves to separate RF transmission and reception. The first LNA 12 amplifies the RF signal while suppressing the generation of noise as much as possible in order to transfer the weakly received signal through the antenna 10 from the aerial line (base station) into an optimal signal form. An RF Surface Acoustic Wave (SAW) filter 13 removes the interference signal outside the reception band from the amplified RF signal. The mixer 17 converts the SAW filtered signal into an intermediate frequency (hereinafter, referred to as IF) signal.

The second LNA 15 is selectively connected between the output terminal of the RF SAW filter 13 and the input terminal of the mixer 17 according to the state of the mode selection signal MS. That is, in the first mode, common terminals c1 and c2 of the first switch unit 14 and the second switch unit 16 are connected to input / output terminals of the second LNA 15, respectively. and a terminal b1 and b2 for connecting an output terminal of the RF SAW filter 13 and an input terminal of the mixer 17 in a second mode.

The first mode of the mode selection signal MS indicates a super weak electric field, and the other states are the second mode. Specifically, the ratio of the average transmit energy per pseudo noise chip (hereinafter referred to as Ec / Io) for the pilot channel, the sink channel, the paging channel, the forward channel, and the power controller channel is 10 or more (Ec / Io ≥ 10). ) And the received signal strength indicator (hereinafter referred to as RSSI) is less than or equal to a preset value (RSSI ≤ ), It is considered a weak field. In this case, a high gain mode is entered to switch both LNAs 12 and 15 on. After that, if the above two conditions are not satisfied and the two conditions are not satisfied, the second electric field is considered to be a weak electric field or a normal state, and only the first LNA 12 is turned on to switch to the low gain mode. ) Switches to the off state. The mode selection signal MS is, for example, a portable wireless telephone using a Qualcomm Mobile Station Modem (MSM) chip, and the general purpose input output (General Purpose Input Output): GPIO).

The IF amplifier 18 amplifies the IF signal output from the mixer 17 by a predetermined amount. The IF SAW filter 19 attenuates signal components other than the amplified IF signal by more than a predetermined value (for example, 35 dB). An auto gain control unit (hereinafter referred to as AGC) 17 controls the amplification gain to suppress a change in the output level due to a change in the input level. Although not shown, the output of the AGC 17 is transferred to a portion (eg, BBA (Qualcomm's BBA)) that converts the IF signal into a baseband analog signal and processes it.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible 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, the present invention designes a low noise amplifier in two stages by using a switching element at the front of the wireless transceiver of the CDMA portable wireless terminal, thereby reducing the burden of the rear stage NF, thereby making it possible to make a call by increasing the sensitivity only during a weak electric field. There is an advantage in ensuring the selectivity and fidelity of revelation.

Claims (5)

A receiver of a portable wireless terminal having a first low noise amplifier for low noise amplifying a signal received through an antenna, and a mixer for converting the low noise amplified signal into an intermediate frequency signal. A second low noise amplifier for second amplifying the signal amplified by the first low noise amplifier to the mixer; The first mode and the second low power amplification are generated in the first mode only when the ultra weak electric field is generated, and the weak electric field or the normal state is connected according to the mode selection signal generated in the second mode so that only the first low power amplification is performed. A first switch unit configured to transfer a state of the first low noise amplified signal to an input terminal of the second low noise amplifier or an input terminal of the mixer; A connection state is switched according to the mode selection signal to transfer the second low noise amplified signal to the input terminal of the mixer or to transmit the first low noise amplified signal to the input terminal of the mixer through the first switch unit; Receiver, characterized in that consisting of two switches. The method of claim 1, wherein the mode selection signal, When the ratio of the average transmit energy per pseudo-noise chip for the pilot channel, the sink channel, the paging channel, the forward channel, and the power control channel is greater than or equal to the first predetermined value, and the reception sensitivity is less than or equal to the second predetermined value, the first mode is entered. Characterized in that the receiver. The method of claim 1, And a surface acoustic wave filter which is connected between the first low noise amplifier and the first switch unit and removes an interference signal outside a reception band included in a signal first amplified by the first low noise amplifier. Receiver. In the code division multiple access portable wireless terminal, It has a two-stage low noise amplifier for low-noise amplifying the signal received through the antenna, the two-stage low noise amplifier is to operate only the first stage or to operate both the first and second stages under a predetermined control, the low noise amplified A receiver for converting the signal into an intermediate frequency signal, The mobile station modem generates a mode selection signal in the first mode to operate both the first and second stages in the case of a weak electric field, and generates a mode selection signal in the second mode so that only the first stage operates in the weak field or the normal state. and, And a baseband analog unit connected to the receiving unit and the mobile station modem and converting an intermediate frequency signal output from the receiving unit into a baseband analog signal for processing. The method of claim 4, wherein And the mode selection signal is generated through a universal input / output terminal of the mobile station modem.