KR930006658B1 - Uni-source-typed rf pin diode switch - Google Patents

Abstract

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Description

RF Power Diode Switch Circuit

1 is a conventional circuit diagram.

2 is a circuit diagram according to the present invention.

* Explanation of symbols for main parts of the drawings

10: TX power supply terminal C1, C2, C3: bypass capacitor

C4, C5: DC blocking capacitor D1, D2, D3: Pin diode

L1: Noise Filter MS1, MS2: Microstrip

RFC: RF Choke

The present invention relates to an RF transmission / reception system of radio and mobile communication equipment, and in particular, a single-power RF pin (PIN) diode that can prevent leakage of transmission and reception signals and increase isolation when switching transmission and reception signals. It relates to a switch circuit.

In general, the RF (Radio Frequency) transmission and reception of the system is performed in a bandwidth of 300NHz-3GHz, and bidirectional communication is performed using a duplexer.

In the transmission and reception of the bidirectional communication, signal leakage from the transmission (TX) side to the antenna and signal leakage from the antenna to the reception (RX) side and isolation between transmission and reception are related to the performance of the communication. As it is directly related to quality, measures for this situation are required.

1 is a circuit diagram of the related art, in which the TX power supply terminal 10 and the RX power supply terminal 11 supplying power for RF transmission and reception, the power supply of the TX power supply terminal 10 and the power supply of the RX power supply terminal 11. Noise filter means (L1-L2, R1-R2) for filtering noise of a transmission / reception signal connected to the first-second switch (SW1-SW2) and the first-second switch (SW1-SW2), respectively. , C1-C6, and the RF choke RFC1-RFC2 connected to the noise filter means R1-R2, respectively, having a high impedance characteristic, and connected between the RF choke RFC1 and the transmitting end TX. And an anode is connected to the DC blocking capacitor C7 and the DC blocking capacitor C7 to block the DC component of the transmission signal, and is transmitted to the transmitting terminal TX when the first switch SW1 is switched. A cathode is connected to a first pin diode D1 that emits a signal to an antenna ANT and a cathode of the first pin diode D1 to the second switch SW2. The second diode D2, which conducts the RF reception signal flowing from the antenna ANT and passes through the switching, and a DC blocking capacitor connected between the cathode of the first diode D1 and the antenna ANT ( C8) and an RF choke (RFC3) connected between the cathode of the first pin diode (D1) and ground. A third pin diode D3 having a cathode connected to the anode of the second pin diode D2, a DC blocking capacitor C9 connected to an anode of the second pin diode D2, and the DC blocking capacitor C9) and a microstrip (MS) having a length of λ / 4 and for impedance matching. A fourth pin diode D4 and an RF choke RFC4 connected to the side end of the micro strip MS, and a DC block connected to the micro strip M8 to receive an RF received signal from the antenna ANT And a DC blocking capacitor C10 for applying to the receiving terminal RX.

The upper portion A of the RF choke RFC4 is connected to the connection point A of the RF choke RFC1.

Briefly describing a conventional RF pin diode switch circuit based on the configuration of FIG. 1, first, in a receive mode (RX Mode), the second switch SW2 of the RX power supply stage 11 is turned ON and the TX power supply is turned on. The first switch SW1 of the stage 10 is turned OFF. Here, the power of the RX power supply terminal 11 is applied from a battery (not shown) and the power is for applying a bias bIAS to the second pin diode D2.

Therefore, the RF reception signal flowing from the antenna ANT must pass through the DC blocking capacitor C8 so that the second pin diode D2, the DC blocking capacitor C9, and the micro strip MS and the DC blocking capacitor It passes through the C10 and is input to the receiving end RX.

In this case, the RF reception signal does not pass through the first pin diode D1 in the reception mode because the signal is reversed.

At this time, the receiving end RX and the transmitting end TX are said to be isolated.

In the transmission mode, the RF transmission signal provided from the transmitting end TX is radiated to the antenna ANT through the DC blocking capacitor C7, the first pin diode D1, and the DC blocking capacitor C8. .

In the transmission mode, the first switch SW1 of the TX power terminal 10 is turned on and the second switch SW2 of the RX power terminal 11 is turned off. Considering the conventional circuit, it can be seen that the power supply of the TX power supply terminal 10 is applied in the transmission mode and the power supply of the RX power supply terminal 11 is applied in the reception mode. This positive power supply method has the disadvantage of increasing the power consumption.

In addition, the RF choke (RFC1-RFC4) used in the circuit is composed of a strip line having a high impedance (size), the size (λ / 4) (where λ is the same as the microstrip (MS)) Is the wavelength of the signal). These RF chokes (RFC1-RFC4) and microstrip (MS) not only occupy an area on a printed circuit board (PCB) board, but also do not sufficiently choke for a transmission signal having a large output level. There has been a problem causing the leakage of the (Leakage) phenomenon.

The leakage phenomenon affects the phase synchronization circuit of the communication system and the like, which causes another problem of releasing the locking of the local oscillation signal, which often causes an uncommunicable state.

In the circuit, the first-fourth pin diodes D1-D4 are a variable resistance diode and form an intrinsic semiconductor layer I (Intrinsic) layer having a very small impurity concentration and a relatively thick thickness between the P layer and the N layer. Wide-band high-cost, low-cost RF switch is an expensive diode, which has been a barrier to the reduction of manufacturing cost.

Accordingly, an object of the present invention is to provide an RF pin diode switch circuit of a single power supply type that can prevent leakage of a transmission / reception signal and increase isolation in view of the above problems.

Another object of the present invention is to reduce the current consumption and the number of pin diodes by providing a single-supply RF pin diode switch circuit.

It is still another object of the present invention to provide a single power supply type RF pin diode switch circuit which can simplify the circuit and improve communication quality.

The present invention for achieving the above object is characterized in that the pin diode and RF choke is reduced compared to the conventional and transmit and receive only with a single power supply.

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

2 is a circuit diagram of the present invention, comprising: power supply means for RF transmission and reception, filtering means for filtering noise of an RF transmission signal connected to the power supply means and applied from a transmitting end TX; A first conduction means connected to the RF transmission signal of the transmitting end TX to the antenna ANT when the power is supplied from the power supply means, and connected to the first conduction means to When the power is applied, the RF transmission signal of the transmitter TX is isolated, and when the power is not supplied from the power supply means, the RF reception signal input from the antenna ANT is input to the receiver RX. And an input matching means.

Here, the power supply means comprises a TX power supply stage 10 and a switch SW1, and the filtering means includes a bypass capacitor C1-C3, a DC blocking capacitor C4, a noise filter coil L1, and The resistor R1 and the RF choke RFC are formed, and the first conducting means is made up of the first pin diode D1.

The input matching means includes a micro strip MS1-MS2 having a length of λ / 4, a second and third pin diode D2-D3 connected between the micro strip MS1-MS2 and ground, respectively; And a DC blocking capacitor C5 connected between the MS2 and the receiving terminal RX.

Hereinafter, the present invention will be described in detail with reference to FIG. 2 based on the above-described configuration.

First, in the present invention, the isolation in transmission / reception mode is increased by using a λ / 4 (where λ is a wavelength of an RF signal) microstrip (or strip line) having an impedance characteristic of a predetermined value. It consisted of.

In FIG. 2, in the reception mode, the RF reception signal received through the antenna ANT is not connected to the transmitting terminal TX because the first pin diode D2 is connected in the reverse direction. It is input to the receiving terminal RX through the DC blocking capacitor. At this time, the switch SW1 of the TX power terminal 10 is in an OFF state.

That is, in the reception mode, since the bias first pin diode D1 is not biased, it is in an open state.

The two microstrips MS1-MS2 are λ / 4 microstrip lines, each having a characteristic impedance of 50 ohms, which is matched with the impedance of the antenna ANT, so the reception loss is 1 decibel. (dB) or less.

In the transmission mode, as the switch SW1 of the TX power supply terminal 10 is turned on, a bias is applied to the first pin diode D1 so that the RF transmission signal of the transmission terminal TX transmits a DC blocking capacitor ( C4) and the first pin diode D1 to radiate to the antenna ANT. In this case, the second to third pin diodes D2-D3 are configured together with the micro strips MS1 to MS2 to have isolation characteristics with the receiving terminal RX.

Therefore, the isolation at the time of transmission and reception is increased by the micro strips MS1-MS2, and the number of RF chokes is reduced compared with the prior art. In addition, if the transmission and reception system is operated by the power source, power consumption is reduced.

As described above, the present invention is advantageous in that the quality of communication is improved because the prevention of leakage of the transmitted / received signal is increased and the isolation is increased, and the number of parts can be reduced. have.

Claims (3)

An RF pin diode switch circuit of an RF transmission / reception system for transmitting and receiving as an RF transmission / reception signal, comprising: a power supply means for RF transmission and reception, and filtering noise of an RF transmission signal connected to the power supply means and applied from a transmitting end TX; Filtering means for connecting the first conducting means connected to the filtering means to pass the RF transmission signal of the transmitting end TX to the antenna ANT when power is applied from the power supply means; Is connected to the means isolating the RF transmission signal of the transmitting end (TX) when power is applied from the power supply means, and RF power received from the antenna (ANT) when power is not applied from the power supply means RF pin diode switch of a single power supply type, characterized in that the input matching means for inputting a signal to the receiving end (RX) Circuit. The RF pin diode switch circuit of claim 1, wherein the power supply means comprises a TX power supply terminal (10) and a switch (SW1). The method of claim 1, wherein the input matching means comprises: a microstrip (MS1-MS2) having a characteristic impedance, a second and third pin diode (D2-D3) connected between the microstrip (MS1-MS2) and ground; RF pin diode switch circuit of claim 1, characterized in that it is composed of a DC blocking capacitor (C5) connected between the micro strip (MS2) and the receiving end (RX).

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