JPS609365B2 - Negative impedance repeater with equalization function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative impedance repeater having an equalization function.

When transmitting a wideband signal, the higher the frequency of the signal, the greater the attenuation, so it is necessary to equalize the transmitted signal by emphasizing the high frequency range with a repeater.

Conventionally, repeaters were constructed using a 2-wire to 4-wire conversion method, and LC
Equalization was performed using an equalizer made up of elements and a cascade connection of emitter peaking circuits of transistors using RC elements. However, the repeater has 2 wires -
2-wire negative impedance repeaters have more advantages than 4-wire conversion systems. Conventional examples of 2-wire negative I impedance repeaters that have equal-equal function are differential type. There is a method that uses a fixed impedance converter consisting of an operational amplifier, makes the impedance connected to it negative and positive, and gives the impedance element a Takagi increasing characteristic.

In this case, the impedance element must include an inductance element in order to have high-frequency increasing characteristics, but it is difficult to adjust the frequency characteristics of the inductance element, and it is difficult to adjust the frequency characteristics of the inductance element. It is not easy to provide such frequency characteristics. The purpose of the present invention is to
It is an object of the present invention to provide a negative impedance repeater that can easily realize not only first-order but also high-order equalization performance using RC elements.

In the repeater of the present invention, certain conditions are specified for the amplification constant of the amplifier of each negative impedance circuit in the non-impedance repeater which is formed by coupling sub-impedance circuits to the series limb and the parallel limb of a hybrid transformer. There is a characteristic in that.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a basic configuration diagram of a negative impedance repeater. In Figure 1, T is a hybrid transformer, Ts is its series leg transformer (series transformer), and TP
is a parallel limb transformer (parallel transformer). The winding ratio of the series transformer Ts is 11:21, and the winding ratio of the parallel transformer TP is 10 nP. 1Zs is a negative impedance circuit of the series limb (series impedance circuit), 1ZF is a negative impedance circuit of the parallel limb (parallel impedance circuit), and these impedance circuits 1Zs and 1ZP are the series transformer Ts and the parallel Connected to the secondary side of transformer TP. The series impedance circuit 1Zs is formed by connecting the input and output terminals of an amplifier AMPs with a high input impedance and a gain of 10 As (As>0) through a resistor Rs. The configuration of the parallel impedance circuit-ZP is also similar. A negative impedance circuit is generally represented as shown in FIG. 2, and if attention is paid to the input and output of the amplifier AMP of this circuit, the following relationship holds true.

v.

Urko(10A)V,N'1}1...i(
V...-V side T〉Poison (2) ^Z...≦¥・;:-grave (3) Applying this result to the series impedance circuit -Zs and the parallel impedance circuit -ZP in Figure 1, we get ZS=
(4) ZP= (5) is obtained.

At this time, the image impedance of the repeater is Z.

=Time =;'' If it is assumed that this matches the characteristic impedance Ro of the transmission line, then the gain of the repeater is given by the following equation.

■, {From formula 7, As and Ap are kept constant, As
It can be seen that by giving a high-frequency attenuation characteristic to the repeater gain K, the repeater gain K can be given a high-frequency emphasis characteristic, that is, an equalization function, while maintaining the matching condition.

Such an impedance circuit can be realized, for example, by a circuit as shown in FIGS. 3a and 3b, which is constructed using an operational amplifier.

In FIG. 3, a is a series impedance circuit and b is a parallel impedance circuit. Since the input impedance of these circuits is expressed by each, As and AP are respectively expressed as follows: RS2'CS: RP3'CP (12) RS2'/RS2 = RP3'/RP3 (13
), it is possible to give As a Takagi damping characteristic while satisfying the constant condition of As·AP=.

That is, it is possible to give the gain K of the repeater a Takagi emphasis characteristic while maintaining matching. In formula (2), R
Since the value of ZP does not change even if P and the next numerator term are interchanged, the parallel impedance circuit may be constructed as shown in FIG. The above is an example of realizing a first-order equalization function, but to realize a second-order equalization function, a series impedance circuit and a parallel impedance circuit are required.
It can be done as shown in Figures a and b. Thus, the present invention
In an amplifier with a gain of 10 A for a negative impedance circuit, the amplification constant A is set to have a Takagi attenuation characteristic for the negative impedance circuit in the series limb, so an RC element can be used without using an inductance element. Only 1
Next, of course, a negative impedance repeater is obtained in which a high-order equalization function can be easily realized.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of a negative impedance repeater, Fig. 2 is a basic configuration diagram of a sub-impedance circuit, and Figs. 3 to 5 are implementations of a negative I impedance circuit in a repeater of the present invention. This is an example. TH...Hybrid transformer, Ts...Series transformer, TP...Parallel transformer, -Zs,
- ZP...Member impedance circuit, AMP...
・Amplifier, R...Resistance. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 In a repeater in which negative impedance circuits are connected to the secondary sides of the series and parallel limbs of a hybrid transformer, both negative impedance circuits are connected between an amplifier with a gain of 1+A and the input and output terminals of this amplifier. and a feedback impedance connecting the negative impedance circuit of the negative impedance circuit on the series side while keeping the ratio of the value of the feedback impedance in the double negative impedance circuit and the gain constant A of the amplifier constant. A negative impedance repeater characterized in that the gain constant A of has high-frequency attenuation characteristics.