DE102007018165A1 - Switchable RF power divider - Google Patents

Abstract

Circuit arrangement for RF signal distribution, with a power divider (1, 2) with three gates (a, b, c), characterized by at two of the gates (a, b, c) parallel to the line of the power divider (1) g

Description

The Invention relates to a circuit arrangement for RF signal distribution, with a power divider with three gates. In particular, it concerns the invention provides an RF power divider for efficient power distribution over a large output power range in two or more stages Amplifier networks, both narrow and for broadband RF signals.

clear is already known that with switchable RF power dividers a signal, the Z. B. is fed to Tor a, depending on the switching state, either directly come to gate b without losses, or to equal the gates b and c Split parts. The control of the RF power dividers takes place by switching on and off of empty-ended, respectively short closed lines. The realization of the switching functions takes place by the floating introduction of the RF switch in series to the RF line.

Likewise, the patent US 7,123,114 B2 are described in the prior art, in which a three-wire star circuit for RF power distribution is described, in which the adaptation is achieved by the connection and disconnection of empty or shorted at the end lines. The RF switches are groundless in the described implementation and introduced in series with the RF line. This can lead to distortions of the signals to be transmitted due to intermodulation as well as losses caused by the voltage drop across the switch. Another disadvantage is the limited power transmission, as there are no suitable RF switches available for the transmission of higher RF power.

task The invention is to provide a switchable RF power splitter, which allows high RF power transfers and free of distorting influences on the signals to be transmitted is.

These The object is achieved by a circuit arrangement solved with the features of claim 1. advantageous Embodiments of the invention will become apparent from the dependent claims.

According to the invention a circuit arrangement for RF signal distribution with a power divider provided with three gates, with two of the gates two switches are arranged parallel to the line of the power divider against Earth are switched. Preferably, the one switch is set up in such a way that this opposite to the switching state of the other switch Switching state occupies.

According to a further preferred embodiment, the circuit arrangement is a Wilkinson divider with a two λ / 2 lines interconnecting resistor. Alternatively, the circuit arrangement is a Wilkinson divider with two through-connected λ / 2 lines, wherein in each λ / 2 line in each case a resistor with the value R = Z ₀ every λ / 2 line in two λ / 4 lines is arranged subdividing and connected to ground and one of the λ / 2 lines is arranged parallel to another switch (S3).

The Invention will be described below with reference to preferred embodiments and with reference to the accompanying drawings. Show

1 a switchable RF power divider in a star connection,

2 an adapted, switchable RF divider,

3 the simulation diagram of the 3 dB RF power divider,

4 the simulation diagram for a certain switching state,

5 a calculated scattering parameter diagram for the adapted HF divider in 3 dB operation,

6 a scattering parameter diagram of the adapted HF divider in 0 dB operation with closed switches and

7 a three-stage amplifier network with switchable HF dividers.

In 1 is a switchable RF power divider shown, in which the RF switch is connected in parallel to the line to ground and the RF power divider divides the signal either to an output or to two outputs.

Depending on the switching state, a signal which is fed to gate a can either go directly to gate b without losses or be divided equally between gates b and c. The control of the RF power signals is performed by the two switches S1 and S2. If, as in 1 is shown, the switch S1 is closed and the switch S2 remains open, the signal from Tor a is split symmetrically on port b and gate c. The lines at port b and port c have an impedance of Z ₀ , which has the consequence that, viewed from Tor a, at the neutral point an impedance of Z _0/2 sets. In order to achieve a freedom of reflection for Tor a in this case Chen, is connected at a distance 1 from the star point parallel to the line, a capacitance C, whereby the characteristic impedance Z _0/2 at the star point is transformed to Z ₀ at the gate a. As is known, a short-circuited or idle stub can be used instead of a capacity for adaptation. The scattering parameter diagram associated with this 3 dB RF power splitter was determined using a circuit simulator and is in 3 shown. In this figure, it should be noted that the waveforms S21 and S31 are identical, and the reflection factors S22 and S33 are also identical.

The second switching state is reached when the switch S1 remains open and the switch S2 is closed. Since the switch S2 is closed, it provides a short circuit for gate c, which transforms at the neutral point via the λ / 4 line to an open circuit, resulting in a 50 Ω line between gate a and port b. The scattering parameter diagram belonging to this switching state shows 4 , Here, the reflection factor S11 is identical to the reflection factor S22.

It is shown that this switchable RF power divider for Signal division is suitable (S21 or S31 in each case 3 dB) or as simple Transmission line can be used (S21 = S12 with 0 dB).

Another possibility to realize a switchable RF power divider according to the invention in 2 represented by in a switched Wilkinson divider, the switches S1, S2 and S3 are all connected to ground potential. With switches S1, S2 and S3 open, as in the picture 2 As shown, the RF power divider behaves according to the well-known physical principles of a Wilkinson divider, where all three gates are matched. Compared with the conventional construction, λ / 2 lines have also been inserted according to the invention between the points a and b and the resistor R, respectively, which initially do not change the behavior of the RF power divider. Inserting a line length equal to the wavelength does not change the behavior of the 3 dB Wilkinson divider.

The relationships confirm the graph of the calculated scattering parameters in 5 ,

If, however, the switches S1, S2 and S3 connected to earth potential are closed, a nearly lossless 50 Ω line will be created between gate a and port b, which results from the curve in 6 is readable. The closed switches S2 and S3 generate a short circuit across the respective lines which, as transformed over the λ / 4 lines, acts as an open circuit. Thus, no signal components reach the gate c and the resistor R, so that only the line between gate a and b remains effective for RF signals. The 50 Ω adaptation for this switching state takes place, as already described, via a capacitance C at a distance 1 from point a, or by means of branch lines. The simulated scattering parameters of the matched RF divider in 0 dB operation are in 6 shown.

There through the switch no HF current flows, is over The switches also implemented no power, so a heat dissipation from the switch, special forms of switching contacts or other design principles are not required. Another preferred property of Invention is that the power lossless on a Ausgangstor is passed, or uniformly in another switching state or split in a differently defined ratio can be. Furthermore, the system is for all states always adjusted. The switchable power divider can be analogous to the shown two-stage structure on three or more switchable outputs be extended. It is particularly noteworthy that in an n-stage Switch the power depending on the switching state to one, two or all n output ports can be divided equally.

7 shows the realization possibility for a three-stage amplifier network, in which the RF signal to the input 3 a switchable RF splitter 4 passes through appropriate power amplifier 5 is amplified and again via a switchable RF splitter 4 at the exit 6 is available.

Of the Frequency range of the example explained RF power divider is between 2120 MHZ and 2170 MHZ at 50 Ω. The dividers However, they are for different frequency ranges and termination resistors executable.

1

RF power divider

2

custom RF power divider

3

signal input

4

RF divider

5

power amplifier

6

signal output

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - US 7123114 B2 [0003]

Claims (4)

Circuit arrangement for HF signal distribution, with a power divider ( 1 . 2 ) with three gates (a, b, c), characterized by at two of the gates (a, b, c) parallel to the line of the power divider ( 1 ) switches connected to ground (S1, S2). Circuit arrangement according to Claim 1, characterized that one switch (S1) to the switching state of the other switch (S2) is set engaging opposite switching state engaging. Circuit arrangement according to one of the preceding claims, characterized in that the circuit arrangement comprises a Wilkinson divider ( 2 ) with a two λ / 2 lines interconnecting resistor (R). Circuit arrangement according to claim 1 or 2, characterized in that the circuit arrangement is a Wilkinson divider with two interconnected λ / 2 lines, wherein in each λ / 2 line in each case a resistor with the value R = Z ₀ each λ / 2 Line arranged in two λ / 4 lines dividing and connected to ground and one of the λ / 2 lines is arranged parallel to another switch (S3).