State-of-the-art III-V semiconductor devices for microwave/mm-wave and optoelectronic applications

High-speed limiting amplifiers are widely used in data transmission systems. First, limiting amplifiers can be used in die clock recovery circuit including a passive filter (1) to suppress the amplitude variation of the clock signal detected from the input data Second, a limiting amplifier can be used as the main amplifier of an optical data receiver(2). In comparison with gain controlled amplifiers (3), in which the amplitude of the data stream is regulated manually or by means of a voltage detected from the data stream, die amplitude regulating function of a limiting amplifier directly acts on each single bit. A limiting amplifier can therefore suppress both of the fast and slow amplitude variations. There exists no time constant problem in a limiting amplifier as in a gain controlled one. In addition the design of a limiting amplifier is simpler. Third, limiting amplifiers can be used as input and output butlers in a lot of data- and clock-processing circuits. Therefore, the design of a limiting amplifier with a high speed, a high gain and a wide dynamic range is a basic task for the realization of high-speed data transmission systems. A limiting amplifier fabricated using Si-bipolar technology. can be operated at 15 Gb/s with a power consumption of 720 mW (4). An AIGaAs/GaAs HBT limiting amplifier can be operated up to 15 GHz with a power consumption of 1.5 W (5). The limiting amplifier presented in this paper shows a higher bandwidth but needs a much lower dc power.