KR100390497B1 - Local buffer amplifier for dual band communication device - Google Patents

Abstract

The present invention relates to a local buffer amplifier of a dual band communication terminal. Since a conventional local buffer amplifier has a local port in each band, a separate switching is required to match the dual band frequency mixer having the one input port. There is a problem in that the circuit becomes complicated and bulky because more circuits need to be added. Accordingly, the present invention is a terminal configured to be used in a dual band, by satisfying the function of the local buffer in the dual band (Dual Band) with one amplifier, thereby simplifying the power supply circuit and local port by using one power supply There is an effect to simplify the chipset pin count and circuitry due to unification.

Description

LOCAL BUFFER AMPLIFIER FOR DUAL BAND COMMUNICATION DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local buffer amplifier of a dual band communication terminal. In particular, in a terminal configured to be used in a dual band, the separation of local frequencies between each band and the function of a local buffer in a dual band with one amplifier The present invention relates to a local buffer amplifier of a dual band communication terminal, which is suitable for satisfying the following requirements.

Here, the band refers to the 900MHz band (hereinafter referred to as cellular) used in the cellular band and 1.75GHz band (hereinafter referred to as PCS) used in the PCS band.

In addition, the local buffer amplifier (Local Buffer Amplifier) is a part that buffers the output (TX MIX1 / TX MIX2) and outputs the buffer so that the receiving (Rx) frequency is not affected by the transmission (Tx) frequency Means.

1 is a block diagram schematically illustrating a configuration of a local buffer amplifier in a conventional dual band terminal.

As shown here, a local buffer amplifier of a conventional dual band communication terminal includes: voltage controlled oscillators VCO1 and VCO2 for performing local oscillation in each band (cellular, PCS); Reception frequency mixers (RX MIX1, RX MIX2) for converting a high frequency signal (RF) into an intermediate frequency signal in each band by local frequencies output from the voltage controlled oscillators (VCO1, VCO2); Local buffer amplifiers AMP1 and AMP2 for buffering and outputting local frequencies output from the voltage controlled oscillators VCO1 and VCO2 to transmission frequency mixers TX MIX1 and TX MIX2 of each band; A transmission frequency mixer (TX MIX1, TX MIX2) for converting the intermediate frequency signal IF into a high frequency signal RF in each band by the buffered input local frequency; The power supply unit 10 supplies power to each of the local buffer amplifiers AMP1 and AMP2.

As described above, since the transmission (TX) and reception (RX) portions are discretely configured using transistors (not shown), the transmission-side local buffer amplifiers AMP1 and AMP2 are configured according to each band. Each existed.

Hereinafter, the operation and operation of the conventional apparatus configured as described above will be described.

Once the control unit (not shown) outputs the band selection signal BAND SEL to the power supply unit 10, power is supplied to the voltage controlled oscillator VCO1 or VCO2 and the local buffer amplifier AMP1 or AMP2 of the corresponding band.

Accordingly, the local frequency oscillated by the voltage controlled oscillator (VCO1 or VCO2) of each band is input to the reception frequency mixer (RX MIX1 or RX MIX2) of each band, and when the call is connected, the transmission frequency mixer (TX MIX1 or TX MIX2) inputs the local frequency.

In addition, each amplifier AMP1 or AMP2 is enabled and disabled by PCS transmission power PCS_TX_BUF_VCC and cellular transmission power CELL_TX_BUF_VCC separated according to bands.

As such, in the related art, since the transmission frequency mixers TX MIX1 and TX MIX2 exist separately according to bands, the local ports by the respective amplifiers exist separately, but recently, the transmission frequency mixers are implemented as one chip by the development of technology. It became possible.

In this case, the frequency mixer (dual-band frequency mixer) implemented by the one chip is configured to receive all the local frequencies of each band through one local port, and also chip the local frequency of each input band because they are configured to switching by the selection switch that is provided inside a transmission mixer for each band, the local buffer amplifier group having one of the local ports on the exterior of the dual-band frequency mixer were to need.

That is, in the conventional local buffer amplifier, since each local port is present in each band, in order to match with the dual band frequency mixer having one input port, a separate switching circuit must be added. There is a problem that becomes large.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems. By satisfying the function of the local buffer in a dual band with a single amplifier, the power circuit can be simplified by using a single power supply. It is an object of the present invention to provide a local buffer amplifier of a dual band communication terminal that can simplify the chipset pin number and the circuit according to the unification of the local port.

1 is a block diagram schematically illustrating a configuration of a local buffer amplifier in a conventional dual band terminal.

Figure 2 is a block diagram showing the configuration of a local buffer amplifier of a dual band communication terminal according to the present invention.

3 is a circuit diagram showing a detailed embodiment of the configuration of FIG.

*** Description of the symbols for the main parts of the drawings ***

100: single input / output port local buffer amplifier 100a: input impedance matching section

100b: output impedance matching section 100c: power supply section

200: diplexer 300: dual frequency mixer

According to an aspect of the present invention, there is provided a dual voltage controlled oscillator for selectively outputting a local frequency required by a dual band (cellular, PCS) by a band selection signal BAND_SEL; A diplexer for filtering a local frequency output from the dual voltage controlled oscillator and outputting the filtered local frequency to reception frequency mixers RX MIX1 and RX MIX2 of each band; A single input / output port local buffer amplifier receiving the local frequencies of each band output from the dual voltage controlled oscillator through one port and minimizing a reflection coefficient in each band and outputting them to a dual frequency mixer; The local frequency output through the single input / output port local buffer amplifier is output to the transmission frequency mixers TX MIX1 and TX MIX2 of each band by an internal selection switch SW1 switched according to the band selection signal BAND_SEL. It is characterized by including a frequency mixer.

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

2 is a block diagram showing the configuration of a local buffer amplifier of a dual band communication terminal according to the present invention.

As shown, the present invention provides a dual voltage controlled oscillator (Dual VCO) for selectively outputting the local frequency required for each band (cellular, PCS) by the band selection signal BAND_SEL; A diplexer (200) for filtering the local frequencies output from the dual voltage controlled oscillator (Dual VCO) and outputting the received frequency mixers (RX MIX1 and RX MIX2) of each band; Single input / output port local buffer amplifier receiving local frequency of each band output from the dual voltage controlled oscillator (Dual VCO) through one port and minimizing the reflection coefficient in each band to output to the dual frequency mixer 300 100; Transmit frequency mixers TX MIX1 and TX MIX2 of each band by an internal select switch SW1 that switches the local frequency output through the single input / output port local buffer amplifier 100 according to the band select signal BAND_SEL. It comprises a frequency mixer 300 to output to).

Here, the dual voltage controlled oscillator (Dual VCO) oscillates the local frequency required by each band (cellular, PCS) by the band selection signal BAND_SEL output from the controller (not shown).

Next, the diplexer 200 filters the frequencies of the two bands and outputs them to each of the reception frequency mixers RX MIX1 and RX MIX2.

Next, the single input / output port local buffer amplifier 100 receives a local frequency of each band output from the dual voltage controlled oscillator (Dual VCO) as one port and actively performs impedance matching according to the local frequency of each band. By doing so, the reflection coefficient in each band is minimized and output.

Next, the dual frequency mixer 300 selects a local frequency of each band output from the single input / output port local buffer amplifier 100 by a band select switch SW1 switched by a band select signal BAND_SEL. Input to each transmit frequency mixer (TX MIX1 or TX MIX2).

Particularly, the single input / output port local buffer amplifier 100 has impedance matching in both frequency bands, that is, the input impedance matching unit 100a and the output impedance matching unit provided at the input terminal and the output terminal of the amplifier AMP. 100b).

As described above, the impedance matching is actively performed according to the frequency band because it uses the reactor L and the capacitor C whose characteristics vary depending on the frequency, unlike the resistor R.

In other words, in the matching, the series-connected reactor (Series L) has a higher change rate in the Smith chart (not shown) than the low frequency component at the same L value ( ), The series-connected capacitor (Series C) is the opposite of Series L ( ).

In addition, the parallel connected reactor (Shunt L) has a large movement chart of the Smith chart at low frequency as opposed to the Series L ( The paralleled capacitor (Shunt C) is the opposite of Shunt L ( ).

By using the reactor (L) and the capacitor (C) as described above to achieve impedance matching, it is possible to use a single buffer amplifier can be unified the power supply, so that the power supply selection switching is not necessary As a result, the number of component mountings can be reduced, thereby reducing the size of the circuit.

3 is a circuit diagram showing a detailed embodiment of the configuration of FIG.

As illustrated, the dual voltage controlled oscillator Y having frequency characteristics of the 967 MHz band and the 1.75 GHz band selectively oscillates the local frequency of each frequency band by the band selection signal BAND_SEL.

Next, the local frequency oscillated as described above is input to the amplifier Q through the input impedance matching unit 100a.

At this time, the input impedance matching unit 100a is composed of reactors L1 and L2 and capacitors C1 and C3, and the capacitor C3 serves as an AC ground of the reactor L2 and the reactor L2 is The input port impedance S11 of the S parameter is moved on a 50Ω circle in an impedance chart (not shown), and the capacitor C1 moves a lot of low frequency components while reducing the movement of the high frequency components.

This results in a closer distance on the Smith charts (not shown) of 967 MHz and 1750 MHz, and then further narrows the spacing using reactor L1 to bring the two frequency components around 50 Ω.

Next, the output impedance matching section 100b is composed of reactor L3, capacitors C2, C4, C5, and resistor R3, where reactor L3 is used as a bias choke, and capacitor C 4 is For the AC ground of reactor L3, resistor R3 and capacitor C5 were used for stabilization of amplifier Q.

C2 is used for the purpose of the DC block to block the DC component, and output only the frequency component to the dual frequency mixer 300.

Next, the power supply unit 100c is for supplying power to the amplifier Q, and divides the voltage VCC by the resistors R1 and R2 to supply a bias to the base end of the amplifier Q.

As described above, the local buffer amplifier of the dual band communication terminal of the present invention is a terminal configured to be used in the dual band, and one power supply is satisfied by satisfying the function of the local buffer in the dual band with a single amplifier. There is an effect of simplifying the power supply circuit and the chipset pin number and the circuit according to the unification of the local port.

Claims (5)

A dual voltage controlled oscillator for selectively outputting a local frequency required by a dual band (cellular, PCS) by a band selection signal BAND_SEL; A diplexer for filtering a local frequency output from the dual voltage controlled oscillator and outputting the filtered local frequency to reception frequency mixers RX MIX1 and RX MIX2 of each band; Single input / output port local buffer amplifier receiving local frequency of each band output from the dual voltage controlled oscillator through one port and minimizing the reflection coefficient in each band by matching input and output impedance Wow; The local frequency output through the single input / output port local buffer amplifier is output to the transmission frequency mixers TX MIX1 and TX MIX2 of each band by an internal selection switch SW1 switched according to the band selection signal BAND_SEL. A local buffer amplifier of a dual band communication terminal comprising a frequency mixer. The dual voltage controlled oscillator of claim 1, wherein the single input / output port local buffer amplifier has an output terminal of the dual voltage controlled oscillator and an input terminal of the amplifier so that impedance matching can be achieved regardless of frequency band in a dual band. An input impedance matching unit for actively matching impedance according to a frequency band of a signal output from the signal; An output impedance matching unit for actively impedance matching the output terminal of the amplifier and the input terminal of the dual frequency mixer according to the frequency band of the signal output through the amplifier; And a power supply unit for supplying power to the amplifier. 3. The reactor of claim 2, wherein the input impedance matching unit comprises: a first reactor configured to receive a local frequency output from the dual voltage controlled oscillator to one side; A capacitor connected in series with the reactor and an input of the amplifier; A second reactor for applying a power supply voltage applied from a power supply to an input terminal of the amplifier; Local buffer amplifier of a dual-band communication terminal, characterized in that consisting of a capacitor connected to the AC ground in parallel to the second reactor. The reactor of claim 2, wherein the output impedance matching unit comprises: a reactor used as a bias choke of the amplifier; A first capacitor connected in parallel with the reactor and AC grounded; To stabilize the amplifier connected to one side is parallel to the output of the amplifier and the resistor; A second capacitor connected in series with the resistor and having one side grounded; And a third capacitor connected to an output terminal of the amplifier to block a DC component from a signal output to a dual frequency mixer and output only a frequency component. The local buffer amplifier of any of claims 2 to 4, wherein the amplifier is a transistor.