A 10-Gb/s Inductorless CMOS Limiting Amplifier With Third-Order Interleaving Active Feedback

Abstract

This paper presents an inductorless circuit technique for CMOS limiting amplifiers. By employing the third-order interleaving active feedback, the bandwidth of the proposed circuit can be effectively enhanced while maintaining a suppressed gain peaking within the frequency band. Using a standard 0.18-mum CMOS process, the limiting amplifier is implemented for 10-Gb/s broadband applications. Consuming a DC power of 189 mW from a 1.8-V supply voltage, the fabricated circuit exhibits a voltage gain of 42 dB and a -3-dB bandwidth of 9 GHz. With a 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sup> -1 pseudo-random bit sequence at 10 Gb/s, the measured output swing and input sensitivity for a bit-error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12 </sup> are 300 and 10 mV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , respectively. Due to the absence of the spiral inductors, the chip size of the limiting amplifier including the pads is 0.68times0.8 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> where the active circuit area only occupies 0.32times0.6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>