Low-power-consumption two-step feedforward adder circuit

Abstract

The invention discloses a low-power-consumption two-step feedforward adder circuit, comprising a four-input passive adder and a 2N-input active adder for providing feedforward accumulation signals for the four-input passive adder, wherein N is a natural number more than 1. In the invention, by combining the respective advantages of the active adder and the passive adder, the accumulation of integral feedforward input signals of all integrators in a modulator is realized by using the active adder, the addition between the feedforward accumulation signals and system feedforward signals is realized by using the passive adder, and thus, the problem of attenuation of voltage output signals is solved, the full magnitude of the system feedforward input signals can be made close to the magnitude of a power supply voltage, the property of high precision is achieved, the integral power consumption of the adder circuit is effectively reduced, the requirement on design of an operational amplifier and a multi-bit quantizer is lowered, and no static power consumption is generated; and the low-power-consumption two-step feedforward adder circuit is particularly suitable to the field of Sigma-delta analog-to-digital conversion.

Description

technical field [0001] The invention belongs to the technical field of microelectronic analog-to-digital conversion, and in particular relates to a low-power consumption two-step feed-forward addition circuit. Background technique [0002] With all kinds of portable electronic devices now coming to millions of households and various industrial applications, the demand for analog-to-digital converters as the interface between analog signals and digital signals is also increasing. The Sigma-delta modulator, as the main component in the analog-to-digital converter, is widely used due to its unique high precision. Such as figure 1 As shown, the feedforward structure is currently a mainstream structure of the Sigma-delta modulator, and the Sigma-delta modulator using the feedforward structure needs an adder to output the feedforward output of the integrators at all levels in the Sigma-delta modulator Added to the system feed-forward input signal. [0003] There are two types o...

AI Technical Summary

Problems solved by technology

The active adder is mainly composed of an operational amplifier. When the input signal increases, the output of this adder will also increase to the corresponding amplitude. In the case of full scale, the power consumption of the operational amplifier will become very large; at the same time , when the full-scale input reaches the supply voltage, the operational amplifier is saturated, and its non-linear error will increase, thereby affecting the accuracy

In order to avoid excessive nonlinear errors, the full-scale input of the active adder is generally designed to be smaller than the power supply voltage, but this will correspondingly reduce the range of the input signal

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