一种新颖的OTA结构的数模转换器

A Novel OTA Digital-Analog Converter

介绍了一种新颖结构的数模转换器,此转换器的设计核心是采用跨导运算技术,由CMOS运算跨导放大器(OTA)构成。此D/A转换器以模拟电流作为主要信号变量,以跨导运算放大器取代电压运算放大器,以基于OTA的有源元件取代部分无源元件,通过改变OTA的偏置电流,从而改变其互导增益gm和电压放大器增益Au,更适合于IC的集成。采用9个OTA构成一个8位的加法电路,8个OTA的互导增益gm对应8位的数字信号,8个MOS管作为开关运用由8位的数字信号控制,从而实现数字信号到模拟信号的转换。

This paper presents a novel digital-to-analog converter（DAC） of OTA topologies. It applies the technology of operational transconductance and is composed of CMOS operational transconductance amplifiers （OTA）. The analog current is the main variable in the DAC. The external passive devices are replaced by active devices. The gain of voltage amplifier Au and transconductance gmcan be changed by altering the bias current of the OTA. Therefore this converter is more suitable for IC integration. In this paper an eight-bit adder is composed of nine OTAs. The transconductance gm of eight OTAs corresponds to an eight-bit digital signal. The eight MOSFETs are used as switches and controlled by eight-bit digital signals. Thus the digital signal is convened into the analog signal.