The Logarithmic Amplifier with I/O Characteristic Approaching Horizontal Line
A special logarithmic amplifier, which input signal dynamic range is 0-90 dB and output signal dynamic range is 1-1.2 times, is described in the key point of the current design compared with conventional methods. The I/O characteristic of the logarithmic amplifier shows approximately a horizontal line. Instead of the main intermediate frequency amplifier circuit with automatic gain control of radar, the special logarithmic amplifier was applied to track the plane and test it in airport. It is superior to common automatic gain control circuit for its much lower failure rate, inexpensive in some occasion, especially the perfect function of anti-jamming ability. Experimental results and data analysis illustrating the performance of the design are presented. Meanwhile, this circuit can be applied in military and civil products that need automatic control system of open loop.
Tianbiao Zhang and Jerry Tian
H. Wang and G. H. Liu, "The Logarithmic Amplifier with I/O Characteristic Approaching Horizontal Line", Advanced Materials Research, Vol. 298, pp. 257-261, 2011