DAC1003D160 데이터 시트보기 (PDF) - NXP Semiconductors.

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DAC1003D160

Dual 10 bits DAC, up to 160 MHz, 2 x interpolation

NXP Semiconductors. 

NXP Semiconductors

DAC1003D160

Dual 10 bits DAC, up to 160 MHz, 2 x interpolation

7. Functional description

The DAC1003D160 is a segmented architecture composed of a 7-bit thermometer

sub-DAC and the remaining 3-bit in a binary weighted sub-DAC.

The device produces two complementary current outputs on both channels, respectively

pins IOUT/IOUTN and QOUT/QOUTN which need to be connected via a load resistor to

the ground.

Figure 3 shows the equivalent analog output circuit of one DAC, which consists of a

parallel combination of PMOS current sources and associated switches for each segment.

The cascade source configuration enables the increase of the output impedance of the

source and the improvement of the dynamic performance of the DAC by introducing less

distortion.

Figure 4 shows the internal reference configuration. In this case the bias current is given

by the output of the internal regulator connected to the inverting input of the internal

operational amplifiers, while external resistors RI and RQ are connected respectively to

pins IVIRES and QVIRES. Thus the output current of the two DACs is typically fixed to

20 mA with an appropriate choice of these resistors. This configuration is optimal for

temperature drift compensation because the band gap can be matched with the voltage

on the feedback resistors.

The relation between full-scale output current IO(fs) and the RI (RQ) is:

RI = 2----0---4-8--8-2---×--×---V-I---OG----(A-F--P--S-O-)---U---T- Ω

The output current can also be adjusted by imposing an external reference voltage to the

inverting input pin GAPOUT and disabling the internal band gap with pin GAPD set to

HIGH. At a voltage lower than 1.2 V the current can be set at values lower than 20 mA.

The input references at pins IVIRES and QVIRES may also be driven by separate

reference voltages to adjust independently the two DAC currents.

DAC1003D160

GAPD

AGND

GAPOUT

INTERNAL

BAND GAP

IOUT/QOUT

DAC1003D160

IOUTN/QOUTN

RI

IVIRES

I DAC current

sources array

RL

RL

AGND AGND

014aaa537

RQ QVIRES

Q DAC current

sources array

014aaa538

Fig 3. Equivalent analog output circuit

Fig 4. Internal reference configuration

DAC1003D160_2

Product data sheet

Rev. 02 — 13 August 2008

© NXP B.V. 2008. All rights reserved.

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