Digital-to-analog conversion circuit and digital-to-analog conversion method

Abstract

The present invention relates to a digital-to-analog conversion circuit and a digital-to-analog conversion method thereof. The digital-to-analog conversion circuit converts a digital input signal into an analog signal, including: a PWM encoding circuit, which performs 3-stage PWM encoding on a modulated output signal And generate a first and a second PWM signal, wherein the digital-to-analog conversion circuit generates a modulated output signal according to the input signal, and within a PWM period, corresponding to each value of the modulated output signal, the first and the second PWM signal are respectively having a first and second predetermined number of rising edges and falling edges, wherein the duty ratios of the first and second PWM signals are both a minimum duty ratio greater than 0 when the modulated output signal is equal to an intermediate value; and a The current signal conversion circuit generates a 3-level current signal according to the first and second PWM signals, wherein when the first and second PWM signals represent a zero-order code, the current signal is a zero-order current, and its noise is smaller than other order currents.

Description

technical field [0001] The present invention relates to a digital-to-analog conversion circuit, in particular to a digital-to-analog conversion circuit capable of reducing intersymbol interference (Intersymbol interference, ISI) and noise when the input level is low. The invention also relates to a digital-to-analog conversion method. Background technique [0002] Generally speaking, in a continuous time current digital-to-analog conversion circuit (continuous time currentDAC), inter symbol interference (ISI) is used to indicate that the current cell (current cell) is between different input values, because for example but not Limited to errors caused by imperfect factors such as asymmetrical switching or clock skew, in order to solve this problem, an additional ISI cancellation circuit is often used in the prior art to reduce ISI, which will increase cost. [0003] In addition, high-efficiency DAC circuits often need to use multi-bit sigma-Deltamodulation circuits, and in...

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Problems solved by technology

[0004] In the 2-stage current mode DAC circuit commonly used in the prior art, another common problem is that the current unit in the DAC circuit will continue to output noise on the output signal of the DAC circuit even when the input signal is 0 , so when the input signal is relatively small, the noise in the current unit becomes the main factor affecting the performance of the DAC circuit

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