Semiconductor Manufacturing International (shanghai) Corporation

Semiconductor Manufacturing (shanghai) Corporation

Qianyu Yu

Josh Yang

Hao Liu

Zhibing Deng

The present invention provides a low jitter CMOS to CML converter, including: a differential circuit including differential pair transistors, a pair of loads and a biased transistor, each differential transistor of the differential pair transistors having an input terminal, an output terminal and a connection terminal. With the current compensation device, an additional current path may be provided for the current of the biased transistor which is used as a constant current source when the differential transistors are turned off, so that the peak tail current in the biased transistor current may be eliminated. Thus, the problem caused by the tail current that the common mode output voltages of the converter is unstable and has a high jitter may be solved.

Low jitter CMOS to CML converter

A parallel to serial conversion circuit includes a plurality of switching units and a voltage output unit providing an operating voltage for the switching units. Each of the plurality of switching units is operable to receive a first clock signal and a second clock signal which have the same frequency, a phase shift exists between the first clock signal and the second clock signal for each of the switching units, and a phase difference exists between the first clock signals received by adjacent two switching units of the plurality of switching units. The plurality of switching units receive data bits of parallel data in sequence according to the phase difference, particularly, each of the plurality of switching units receives one data bit within a time window corresponding to the phase shift. In comparison with the prior art, the inventive solution implement the parallel to serial conversion using a single system clock frequency, so that the complexity and power consumption of the system is reduced.

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Shanghai, China

Qianyu Yu