Rail-to-rail output circuit of high-speed fully differential amplifier and high-speed fully differential amplifier

Abstract

The invention provides a rail-to-rail output circuit of a high-speed fully-differential amplifier and the high-speed fully-differential amplifier. The structural design of a high-speed transconductance amplification stage and a novel complementary common-emitter push-pull output stage is combined; therefore, high-speed transconductance amplification and buffering can be carried out on a differential signal output by a pre-stage of the amplifier, and rail-to-rail output close to a positive/negative power supply is realized; through a feedback network arranged between the output end and the input end, the frequency roll-off can be effectively compensated, and the output stability is improved; the rail-to-rail output circuit is realized based on a complementary bipolar process and an all-longitudinal transistor, and high-speed amplification and rail-to-rail output are realized while a high-speed operational amplifier is ensured to be applied by reducing power supply voltage, so the signal-to-noise ratio and the speed/bandwidth index of the rail-to-rail output circuit are not influenced.

Description

technical field [0001] The invention relates to the technical field of semiconductor integrated circuit design, in particular to a rail-to-rail output circuit of a high-speed full differential amplifier and a high-speed full differential amplifier. Background technique [0002] Amplifiers are an integral part of most circuits, and their performance largely determines the performance of the entire circuit or even the system. With the popularization of battery-powered portable devices, working under low-voltage and low-power consumption conditions has gradually become an essential requirement for the system. The most immediate effect of lowering the supply voltage is a reduction in the output signal amplitude, which results in a significant reduction in the signal-to-noise ratio. Compared with single-ended output amplifiers, the differential output amplitude of fully differential output amplifiers can be doubled, which can greatly improve the signal-to-noise ratio of the syst...

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Problems solved by technology

[0004] ①, such as figure 1 In the NPN emitter follower output stage shown in (a), the positive saturation voltage drop of this output structure is much larger than the negative phase saturation voltage drop, and the negative slew rate is severely limited, so it is impossible to achieve rail-to-rail output and large slew rate;

[0005] ②, such as figure 1 The NPN and PNP complementary follower outputs shown in (b), the output swing of this output structure h

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