JPS5863202A - High frequency pulse power amplifier - Google Patents

Abstract

PURPOSE:To improve the efficiency of a high frequency pulse power amplifier using normally-ON element, by having a working state only with the input of a high frequency signal. CONSTITUTION:A high frequency applied to a high frequency input terminal 1 is detected by a high frequency signal detecting circuit 2, and this information is reported to a bias control circut 4. Based on this information, the circuit 4 turns on and off of the bias current and applies a bias to a power amplifier 3 only while the high frequency signal is applied. As a result, the amplifier 3 can be actuated only when the high frequency signal is applied to the amplifier 3. Thus a high frequency pulse signal can be amplified with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flat frequency pulse power amplifier in the microwave band. - as GaAs Ml
i;Relates to improving the efficiency of high-frequency pulse power amplifiers using elements such as S FETs that operate in a mu-class bias state.

Generally, a semiconductor amplification element such as a piezoelectric transistor or FET is used for the purpose of amplifying a high frequency signal, and a high frequency amplifier is constructed by combining this with a high frequency matching circuit and a DC bias circuit.

Especially when operating efficiency is an issue, such as in power amplifiers,7
In the example using Nosta, the operating state at
- It is normal to make it grade C.

Only when this C@dynamic operation bulky high frequency signal is input, the DC bias current flows, and the input is 0N like the flattened a pulse signal.
- It is possible to amplify signals that are turned OFF with efficiency divided by their efficiency.

On the other hand, Ga45 FETs have made remarkable progress in recent years.
Products with performance that surpasses that of the D81 Piborad 2 in the frequency band above GHz are being announced.1. It has been used in various amplifiers and oscillators. 1. Shikashi, this Ga
Aa FET operates in class C, which is different from bipolar transistor! It's difficult to make it work, and it usually moves like crazy! I have to. The DC bias current flows even when the am frequency signal is not input in Class A operation, and the current changes little regardless of the presence or absence of the high frequency signal input.

for example,! 4 wave number 3 GkIm output = zow.

r in ■ 6 dB drain efficiency 30% 1 DC voltage ■ D,
=12.5VIZ) Let us consider the case when the jw width transducer is operated with high frequency pulses. When the duty factor of the input signal is 1ch, 10%, and 100ch, the required DC power does not change much at 67W, and the peak output is 20W.
However, the average output power is 0.2W, 2W, and 20W, respectively. In other words, the overall efficiency is 0.3%, 3
fi, 309G and de, -te (it can be seen that the smaller the factor is, the lower it is. Therefore, when amplifying a high frequency pulse signal, the overall efficiency will be extremely poor. Furthermore, the class C operation Pipo 2 transistor Compared to the case of multipliers, there are many design issues to consider, such as heat dissipation and power capacity.

The present invention eliminates the above-mentioned drawbacks and improves the overall efficiency of a high-frequency pulse power amplifier in the microphone frequency band by activating it only when a high-frequency signal is input. Obtain high frequency/lump voltage amplifier t! I - To serve as a purpose.

Embodiments of the present invention will be described below with reference to the drawings.

The high frequency/odd pulse operating power FIT amplifier shown in Figure 1 is as follows:
The device is equipped with a high frequency signal detection circuit 2 and a bias control circuit 4 for controlling bias current, and is configured such that a drain current flows only when a high frequency signal is input.

That is, as shown in FIG. 1, when a high frequency is applied to the frequency input terminal 1, the high frequency signal detection circuit 2 detects this and notifies the bias control circuit 4 of this information. Based on this information, the bias control circuit 1164 turns on the bias current (O
N), the power amplifier 3 is turned off, and the power amplifier 3 is biased only while the frequency signal is applied.

Therefore, the amplification fitJ can be activated only when the -frequency signal is applied to the amplifier 3, and the high frequency nodal signal can be efficiently amplified. Of course, in the above circuit, due to the difference in the time it takes for the frequency signal to reach the input terminal 1 to the amplifier 3 and the time it takes for the high frequency signal detection circuit 2 and the bias control circuit 4'ft to flow, the high frequency/l pulse Although the width of the fist is observed to be narrower, it is possible to insert a delay line 7 between the high frequency signal detection circuit 2 and the amplifier 3 as shown in Fig. 2, or as shown in Fig. aI3.
When the amplifier section is multi-stage amplified, it is conceivable to use the delay time of the pre-stage amplifier 8 to minimize fluctuations in the -frequency Δ pulse width. 4. Of course, the bias condition of the preamplifier 8 is set to the normal class A operating state.

In this example, the preamplifier 8 operates in class A operation, and the bias current in this portion flows regardless of the presence or absence of a signal. However, the amount is small and it has little effect on overall efficiency.

As described above, according to the present invention, it is possible to obtain a high-frequency /4-ipolar transistor using a normally-on type element such as a GaAs WEB WET, which has obtained performance superior to a /4-ipolar transistor in the frequency band of 3 to 4 G cells or higher. The efficiency of the Luss power amplifier can be improved, and a highly efficient Luss power amplifier can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG.
FIG. 3 is a schematic diagram showing other embodiments of the present invention. 1...^Frequency input terminal, 2...High frequency signal detection circuit, 3...Power booster, 4...Bias control circuit, 5
...DC power supply terminal, 6...High frequency output terminal, 1...
・Delay line, 8...Pre-stage tank Il! i! Profit.

Claims (1)

[Claims] In high-frequency Noculus power amplifiers using normally-on transistors such as GaAs MES FIT,
A high frequency wave/elbow power increaser comprising a high frequency signal detection circuit and a bias control circuit, and activating citranssis through the bias control circuit only when a high frequency signal is input to the power amplifier 1. - vessel.