KR100212054B1 - Transceiver circuits with common used inter frequency - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Transceiver circuit

2. The technical problem to be solved by the invention

The present invention provides a transmission / reception circuit that realizes small size, light weight, and low cost.

3. Summary of Solution to Invention

A plurality of switches that are switched according to the transmission or reception state, characterized in that the transmitter and the receiver is configured to share the intermediate frequency.

4. Important uses of the invention

It is used to allow the transmitter and receiver to share the intermediate frequency.

Description

Intermediate Frequency Sharing Transceiver

1 is a conventional transmission and reception circuit diagram.

2 is another conventional transmission and reception circuit diagram.

3 is an intermediate frequency shared transmission and reception circuit diagram according to an embodiment of the present invention.

4 is an intermediate frequency shared transmission and reception circuit diagram according to another embodiment of the present invention.

5 is an intermediate frequency shared transmission and reception circuit diagram according to still another embodiment of the present invention.

6 shows an example of a specific switch circuit.

* Explanation of symbols for main parts of the drawings

101 modulator 102 intermediate frequency local oscillator

103: intermediate frequency filter 104: radio frequency local oscillator

105.111: Mixer 106: Transmission Filter

107: power amplifier 108: filter and transmission and reception switching unit

109: antenna 110: demodulator

112: reception filter 114, 115: transmission and reception switch

The present invention relates to a transceiver circuit, and more particularly, to an intermediate frequency shared transceiver circuit.

Typically, the GSM RF system includes a transmitter comprising a modulator 101, an intermediate frequency (IF) filter 202, a mixer 105, and a power amplifier 107, and a receiver consisting of a mixer 111, an intermediate frequency filter 212, and a demodulator 110, as shown in FIG. It is composed.

However, in this case, the increase of harmonics and the increase of intermodulation frequency due to the use of too many parts was used, and a surface acoustic wave (SAW) filter was used to eliminate this. This has the disadvantage of increasing the price of the system and increasing the mounting area.

In addition, a direct modulation scheme as shown in FIG. 2 is partially implemented to compensate for the above problem. When the direct modulation scheme is applied to the GSM system, it is common to use a SAW filter and a duplex filter together with a part of the transmitter to satisfy the spurious emission category of the GSM system.

However, in this case, it was difficult to manage the phase error, it was difficult to design a compact and lightweight due to the duplex filter, and it was difficult to meet the GSM PHASE II specification because it was difficult to meet the spurious emission item limit of the EGSM reception band. Therefore, additional SAW filters or high performance SAW or duplex were used to increase the price.

Accordingly, an object of the present invention is to provide a transmission / reception circuit that realizes small size, light weight, and low cost.

The present invention for achieving the above object is characterized in that the transmitter and the receiver is configured to share the intermediate frequency as a plurality of switches that are switched according to the transmission or reception state.

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

First, 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. Also, in the following description, many specific details such as components of specific circuits 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 of ordinary skill 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.

In a typical RF system based on a time division technology such as a GSM system, a receiver does not act during a transmission time, and conversely, a transmitter does not play a role during a reception time. Therefore, the following configuration is possible.

3 is an intermediate frequency shared transmission and reception circuit diagram according to an embodiment of the present invention. In FIG. 3, instead of the functions of the intermediate frequency filters 202 and 212 in FIG. 1, the intermediate frequency filter 103 and the input / output terminal branch switches 114 and 115 are configured to be shared by the transmitter and the receiver.

4 is an intermediate frequency shared transmission and reception circuit diagram according to another embodiment of the present invention. In FIG. 1, the transmitter and receiver share the intermediate frequency filter 403, the mixer 404, and the transmission / reception switches 412 to 415 instead of the functions of the intermediate frequency filters 202 and 212 and the mixers 105 and 111.

That is, during the transmission time, transmission / reception switching is performed so that the modulator 101, the filter for the intermediate frequency 403, the mixer 404 and the RF filter 106, the power amplifier section 107 having a power ramping function, the filter and transmission / reception switching unit 108, and the antenna 109 can be connected and operated. Operate the switch 412 ~ 415.

In addition, during the reception time, the antenna 109, the filter and the transmission and reception switching unit 108, the RF filter 112, the mixer 404, the medium frequency filter 403 and the demodulator 110 is operated to operate the transmission and reception switching switch 412 ~ 415.

For this operation, it is necessary to appropriately distribute the frequency of the transmitter and the receiver so that the intermediate frequency can be shared, and a specific example thereof is shown in FIG. Here, the modulator 101 may use a SIBENS integrated circuit PMB2205. In addition, demodulators, variable amplifiers, mixers, and LNAs denoted by 5A may use PMB2240. And 492 as a local oscillator for the intermediate frequencies in the receiver. Select and after modulation 246 Let it be the intermediate frequency of. The intermediate frequency of the receiver is also 246 Frequency of tunable RF local oscillator 1136-1161 for transmitter Is selected and 1181-1206 for the receiver Select. 1126-1161 for transmitter for EGSM , Select 1171-1126 for the receiver. Select. Transmitters and receivers switches 114 and 115 are added before and after the 246HMz filter.

As shown in FIGS. 3, 4, and 5, it can be seen that a plurality of switches are connected in a cross circuit to share the IF filter or the mixer 404. By employing the cross circuit as described above, not only the bidirectional filter (BIDIRECTIONAL FILTER) but also the unidirectional filter (UNIDIRECTIONAL FILTER) can be used.

6 shows an example of a specific switch circuit. In this case, the SAW filter, such as Murata's SAFC246.000MC30X-TC, eliminates the need to use a duplex filter due to the excellent performance of the SAW filter for intermediate frequencies. Therefore, in such a circuit, a switch such as a switching circuit using a well-known diode and a quarter-wave stripline may be used to replace the duplexer.

As described above, the present invention allows a transmitter and a receiver to share an intermediate frequency with a plurality of switches switched according to a transmission or reception state, and can use both a unidirectional filter as well as a bidirectional filter using a cross circuit. By using the characteristics of the intermediate frequency SAW filter, there is an advantage of realizing small size, light weight and low price of wireless communication equipment.

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.

Claims (11)

A transmitting / receiving circuit having an antenna, comprising: a modulator for outputting a modulated wave by changing a carrier wave according to a signal wave, an intermediate frequency bandpass filter detecting only a signal of an intermediate frequency band from the modulated wave, the modulator and the intermediate frequency bandpass A first transmission and reception switching switch connected between the filter input terminals, a mixer for mixing a predetermined input signal and a second local oscillation frequency, and second and third connecting an output terminal of the intermediate frequency bandpass filter and an input terminal of the mixer during transmission; A transmission / reception switching switch, a first radio frequency bandpass filter detecting only a signal of a transmission band from the mixed signal, and a fourth transmission / reception connected between an output terminal of the first mixer and the first radio frequency bandpass filter A switching switch, a power amplifier for amplifying a signal of the detected transmission band to a certain degree, and a transmission / reception state connected to the antenna According to the connection state is switched at the time of transmission and the transmission unit consisting of the fifth transmission and reception change-over switch for connecting the power amplifier and the antenna; The transmitter and the first to fifth transmission and reception switching switch, the intermediate frequency bandpass filter and the mixer share a linear amplification of a signal transmitted from the antenna connected to the antenna by the fifth transmission and reception switching switch when received. The signal of the reception band and the signal of the reception band through the linear amplifier, a second radio frequency bandpass filter for outputting only a signal of a reception band from the linearly amplified signal, and the third transmission / reception switching switch switched to a reception state. A demodulator for separating the signal wave from the modulated wave when a modulated wave, which is a signal of an intermediate frequency band, is detected through the fourth transmit / receive switch and the intermediate frequency bandpass filter in which a mixed signal of two local oscillation signals is switched to a reception state; Intermediate frequency sharing type transmission and reception circuit, characterized in that consisting of a receiving unit consisting of. The intermediate frequency shared transceiver circuit according to claim 1, wherein the power amplifier has a power ramping function. The method of claim 1, wherein the intermediate frequency is 246 Intermediate frequency sharing type transmission and reception circuit, characterized in that. The method of claim 1, wherein the local oscillation frequency is 1136 to 1161 for transmission. Intermediate frequency sharing type transmission and reception circuit, characterized in that. The method of claim 1, wherein the local oscillation frequency is 1126 to 1161 for transmission. For reception, 1171-1206 Intermediate frequency sharing type transmission and reception circuit, characterized in that. The intermediate frequency sharing type transmission / reception circuit according to claim 1, wherein the intermediate frequency bandpass filter is a surface acoustic wave filter. The intermediate frequency sharing type transmission / reception circuit according to claim 1, further comprising a filter between the third transmission / reception switch and a power amplifier. 8. The intermediate frequency sharing type transceiver circuit according to claim 7, wherein the filter is a surface acoustic wave filter. The intermediate frequency sharing type transmission / reception circuit according to claim 1, wherein the third transmission / reception switching switch is a duplex. The intermediate frequency shared transceiver circuit according to claim 1, further comprising a filter between the third transmission / reception switching switch and the low noise amplifier. The intermediate frequency sharing type transmission / reception circuit according to claim 10, wherein the filter is a surface acoustic wave filter.