Patent ID: 6222473
Filing Date: 2001-04-24
Classification: H03M

Abstract:
An m-bit resolution digital to analog converter (DAC) to convert a digital input signal into a voltage range of an analog voltage output signal, the DAC comprising:a plurality of digital input lines and an analog output line; andan inverted switched R-2R ladder coupled to the plurality of digital input lines for receiving the digital input signal, the inverted switched R2R ladder generating an intermediate analog voltage signal on an intermediate output line in response to the digital input signal, the intermediate output line coupled to the analog output line, the inverted switched R2R ladder comprisinga most significant bit (MSB) switch leg for selectively coupling 2.sup.m-1 /2.sup.m of the voltage range to the intermediate output line to generate the intermediate analog voltage signal in response to the digital input signal,a least significant bit (LSB) switch leg for selectively coupling 1/2.sup.m of the voltage range to the intermediate output line to generate the intermediate analog voltage signal in response to the digital input signal, anda termination leg coupled in parallel with the LSB switch leg, the termination leg having a continuously turned ON switch in series with a resistor, the resistor having an increased resistance to provide linearity over the voltage range and the m-bit resolution.