Super555

The fastest 555 timer chip is TI's TLC 555, a CMOS chip with a fastest oscillation frequency of 2MHz. The purpose of this project is to build a high-speed 555 timer using high-speed components, with an oscillation frequency far exceeding that of traditional 555 chips, suitable for high-speed signal applications. Of course, the primary goal is to learn the design circuitry of the 555 chip, paying tribute to the great analog chip designer Hans Kamenhinid!
 
The internal circuitry of the 555 timer includes three resistor dividers, two comparators, an RS flip-flop with a reset pin, an output driver (OUT), and a discharge transistor.
 
This project implements this circuitry using high-speed components based on the functional diagram above. The comparators use the MAX962 dual comparator, and the RS flip-flop is constructed using NOR gates. The reset pin is not implemented (this could be achieved using a flip-flop chip with a reset pin, such as the 74LVC74). The discharge transistor used was a 9018, but experiments showed that this transistor was not very suitable due to its slow response. It can be replaced with a high-speed OC gate device, such as a 74LVC74HC1G06/07 (thanks to Bilibili fan "Hergolan-Thuringen" for the suggestion). A high-speed comparator could also be a TLV3502, which is more affordable (thanks to Bilibili fan "DualMono" for the suggestion).
 
The circuit has been verified, and the highest measured oscillation frequency is 70MHz.
 
A demonstration video can be viewed on Bilibili: https://www.bilibili.com/video/BV1FU4y187jG