Modified CMOS Cherry-Hooper amplifiers with source follower feedback in 0.35/spl mu/m technology

A CMOS Cherry-Hooper amplifier that is modified to include source follower feedback is described. A small signal model that uses only the most dominant capacitances is used to derive the transfer function of the circuit. The gain is significantly higher than that of the standard MOS Cherry-Hooper stage. Design techniques based on the analysis are suggested for broadband applications. A test circuit, fabricated in a 0.35 /spl mu/m CMOS technology, has 9.4dB gain and 880 MHz bandwidth while consuming 6.0 mA from a 3.3 V supply. Eye diagrams of the test chip at 630 MS/s show good eye opening, giving confidence to the new amplifier´s large signal performance. In addition, a six stage main amplifier using the modified Cherry-Hooper stages was fabricated in a 0.18 /spl mu/m CMOS technology. It draws 44mA from a 1.8 V supply. It has 39 dB single-ended gain, 2.1 GHz bandwidth, and 14.2 dB noise figure.