JPH04258015A - Peaking suppression amplifier - Google Patents

Abstract

PURPOSE:To automatically suppress peaking with respect to the peaking suppression amplifier which suppresses peaking caused in a rectangular wave with an output of an amplifier amplifying the rectangular wave of a digital signal. CONSTITUTION:A varactor diode 1 is connected in parallel with an output of the amplifier, to which a peak detection circuit 2 detecting a peak level of an output waveform and a mean value detection circuit 3 detecting a mean value of an output waveform are connected, and an error amplifier 4 to obtain a difference between the peak level obtained by the peak detection circuit 2 and the mean value obtained by the mean value detection circuit 3 is connected to an output of the peak detection circuit 2 and an output of the mean value detection circuit 3. Moreover, an error amplifier 5 to obtain a difference between a difference between a value obtained by the error amplifier 4 and a value V1 being a difference of the maximum value and the mean value when an output waveform of the said amplifier 4 is a normal rectangular wave, and an output of the error amplifier 5 is given as a bias voltage of the varactor diode 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peaking suppression amplifier that automatically suppresses peaking that occurs in a rectangular wave at the output of an amplifier that amplifies the rectangular wave of a digital signal.

The band of an amplifier for amplifying a rectangular digital signal of, for example, 100 MHz, which changes from 1 level to 0 level, is set to be as wide as 600 MHz, for example, in order not to destroy the waveform.

For this reason, depending on the characteristics of the transistor used in the amplifier, peaking occurs at the rise and fall points of the rectangular wave. It is desired to provide an amplifier that can suppress this peaking without much effort.

0004

2. Description of the Related Art FIG. 4 is a circuit diagram and waveform diagram of a conventional peaking suppression amplifier. The amplifier in Figure 4 receives an ECL level signal as shown in (A) where the 1 level is 0V and the 0 level is -0.8V, and the output is -0.8V and 0 level as shown in (B). It outputs an ECL level signal with a level of -1.6V, and consists of a differential amplifier consisting of resistors R1 and R2, transistors Tr1 and Tr2, and constant current source 6, and a buffer amplifier consisting of transistor Tr3 and resistor R9. ing.

In this case, transistors Tr1, Tr2,
Due to the characteristics of Tr3, peaking may occur at the rising and falling points of the rectangular wave as shown in the output waveform in (B).

For this purpose, resistors R10 and R10 are connected to the output of the amplifier.
Capacitor C3 is inserted to prevent this peaking.

[0007]

[Problem to be solved by the invention] However, in order to find the values of the resistor R10 and capacitor C3 that suppress this peaking, it is necessary to replace them with different values many times to find the appropriate values, which is a hassle. There are problems with this.

An object of the present invention is to provide a peaking suppression amplifier that can automatically suppress peaking.

[0009]

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. As shown in FIG. 1, a voltage variable capacitance diode 1 is connected in parallel to the output of an amplifier that amplifies a rectangular wave of a digital signal, and a peak detection circuit 2 that detects the peak value of the output waveform and the average value of the output waveform are connected in parallel. An average value detection circuit 3 that detects is connected, and the peak value obtained by the peak detection circuit 2 and the average value detection circuit 3 are connected to the output of the peak detection circuit 2 and the output of the average value detection circuit 3. A first error amplifier 4 is connected to calculate the difference between the average value obtained by the first error amplifier 4 and the output of the first error amplifier 4. A second error amplifier 5 is connected to calculate the difference between the maximum value and the average value V1 when the waveform is a normal rectangle, and the output of the second error amplifier 5 is connected to the voltage variable capacitance diode 1. Give it as a bias voltage.

0010

[Operation] According to the present invention, the peak value of the output rectangular wave of the output of the amplifier is detected by the peak detection circuit 2, and the average value of the output waveform is detected by the average value detection circuit 3. The difference between the peak value and the average value is determined by the first error amplifier 4 and the second
input to the error amplifier 5.

The second error amplifier 5 calculates the difference between the value obtained by the first error amplifier 4 and the voltage V1, which is the difference between the maximum value and the average value in the case of a rectangular wave with no output peaking. ,
Find the value of the difference between the maximum value of the rectangular wave and the peak value caused by peaking, and apply this value of voltage as the bias voltage of voltage variable capacitance diode 1 to change the capacitance. In other words, the peak value caused by peaking is automatically controlled to almost disappear.

[0012] That is, since peaking can be automatically suppressed, it is possible to eliminate the trouble of suppressing peaking.

[0013]

Embodiment FIG. 2 is a circuit diagram of a peaking suppression amplifier according to an embodiment of the present invention, and FIG. 3 is a waveform diagram of an example in the case of FIG.

In FIG. 2, a resistor R11 and a voltage variable capacitance diode (varicap) 1 are connected in parallel to the output of the amplifier shown in FIG. An average value detection circuit 3 having a circuit, a transistor Tr5,
A peak detection circuit 2 having a circuit consisting of resistors R5 and R6, a diode D, and a capacitor C2 for determining the peak is connected, and the outputs of the average value detection circuit 3 and the peak detection circuit 2 are as follows.
A transistor T that calculates the difference between the peak value determined by the peak detection circuit 2 and the average value determined by the average value detection circuit 3.
An error amplifier 4 made up of R6, resistors R7 and R8, and an operational amplifier 7 is connected.

Further, the output of the error amplifier 4 is connected to the error amplifier 4.
An error amplifier 5 having an operational amplifier 8 is connected to calculate the difference between the output of the amplifier and the power supply V3 which provides the voltage V1 which is the difference between the maximum value and the average value in the case of a rectangular wave output of the amplifier without peaking. The output of the amplifier 5 is applied to the voltage variable capacitance diode 1 as a bias voltage.

As in the case of the conventional example shown in FIG.
Assuming that a rectangular wave with an ECL level as shown in Figure 2 is input, and the output of the amplifier becomes a square wave with peaking of -0.4V as shown in Figure 3(B), the values of each part in the case of Figure 2 are This will be explained using the waveform diagram in FIG.

The peak detection circuit 2 detects -0.4 of the peak value.
V is detected, and the average value detection circuit 3 detects the average value of -1.2V.
is detected and inputted to the error amplifier 4, which calculates the difference of 0.8V and inputs it to one input of the error amplifier 5.

The other input of the error amplifier 5 has the signal shown in FIG.
) The difference between the average value -1.2V and the maximum value -0.8V of the rectangular wave with no peaking as shown in 0.4V is determined in advance and added from the power supply V3, so the output is 0.4V of the difference. 4
V, this voltage is given as the bias voltage of the voltage variable capacitance diode 1, the capacitance of the voltage variable capacitance diode 1 increases, the peak value becomes low, and the error amplifier 5
output voltage becomes smaller.

When the peak value disappears by repeating such an operation, the output voltage of the error amplifier 5 becomes 0, and at this point, the change in the capacitance value of the voltage variable capacitance diode 1 stops. In other words, since peaking can be automatically suppressed, time and effort can be eliminated.

[0020]

As described in detail above, according to the present invention, a peaking suppression amplifier capable of automatically suppressing peaking can be obtained, and the effort of suppressing peaking can be saved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a circuit diagram of a peaking suppression amplifier according to an embodiment of the present invention;

[Fig. 3] is an example waveform diagram in the case of Fig. 2;

FIG. 4 is a circuit diagram and waveform diagram of a conventional peaking suppression amplifier;

[Explanation of symbols]

1 is a voltage variable capacitance diode, 2 is a peak detection circuit; 3 is an average value detection circuit; 4 and 5 are error amplifiers, 6 is a constant current source, 7 and 8 are operational amplifiers, Tr1 to Tr6 are transistors, R1 to R10 are resistors, C1 to C3 are capacitors, D is a diode, V3 indicates a power supply.

Claims (1)

[Claims] 1. A peak detection circuit (2) that connects a voltage variable capacitance diode (1) in parallel to the output of an amplifier that amplifies a rectangular wave of a digital signal, and detects the peak value of the output waveform; An average value detection circuit (3) that detects the average value of is connected to the output of the peak detection circuit (2) and the output of the average value detection circuit (3). a first error amplifier (4) that calculates the difference between the peak value obtained by the calculation and the average value obtained by the average value detection circuit (3);
and further connect the output of the first error amplifier (4) to the value obtained by the first error amplifier (4), the maximum value and the average when the output waveform of the amplifier is a normal rectangle. A second error amplifier (5) is connected to calculate the difference between the difference value and the value (V1), and the output of the second error amplifier (5) is used as the bias voltage of the voltage variable capacitance diode (1). A peaking suppression amplifier characterized in that it provides a peaking suppression amplifier.