I took first notice of Prof. Tsividis?s work around 1977, when my UCLA students and I started to work on switched-capacitor (SC) circuits. These circuits may perform the same functions (filtering, equalization, amplification) as the traditional active-RC ones, but are more suitable for integrated MOS implementation, since their frequency responses depend only on the ratios of capacitances, which can be accurately controlled in fabricated devices. A key component of SC circuits is the operational amplifier (opamp). The design of CMOS opamps was a new challenge, and the UC Berkeley researchers (with Yannis in the forefront) were the leaders in meeting it. I learnt a great deal from Yannis?s December 1976 JSSC papers [1] [2], and even called him on the telephone a few times to get help with our SC projects. He was most helpful, and we succeded in our design.