PULSE LOGARITHMIC AMPLIFIER WITH AUTOMATIC ADJUSTMENT OF AMPLIFICATION IN THE FREQUENCY RANGE FROM 1 MHZ TO 8 GHZ

At present, the overload problem of pulsed radar receivers of signals reflected from targets is particularly relevant, which is caused by the appearance of new types of radio engineering systems for various purposes. To protect amplifiers against overload, a number of methods are used: automatic gain control (AGC) depending on the level of the input signal, separation of the dynamic range into parts and multichannel amplification, the usage of amplifiers with a logarithmic amplitude characteristic, etc. Good results are obtained by a combination of logarithmic gain and signal AGC. The paper describes a pulsed logarithmic amplifier with inertial automatic adjustment of the signal gain factor, operating in the frequency range from 1 MHz to 8 GHz. The functional and the principal electrical circuits are shown. A small-scale experimental model of the device was developed using a modern element base which greatly expanded the possibilities of its application. The physical basis for selecting the necessary bandwidth, which allows avoiding the distortion of radio pulses spectra and the dynamic mode of operation of the inertial AGC, is considered. Experimentally obtained amplitude characteristics are given. The parameters of the layout are as follows: the gain factor K₀ in the linear section ~53 dB; the dynamic range of input signals ~55 dB; input and output resistance R_in » R_out = 50 Ohm; supply voltage ±12 V (consumption current of 100 mA), ±5 V (consumption current of 20 mA)