ADC32RF83 datasheet(127/138 Pages) TI

127 / 138 page

Input Frequency (MHz)

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1500

-110

-100

-90

-80

-70

-60

-50

-40

-30

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-10

D001

Input Frequency (MHz)

300

600

900

1200

1500

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

D003

CHx_INP

CHx_INM

1:1

(Optional)

0.1 F

1:1

(Optional)

0.1 F

TI Device

CIN

RIN

127

ADC32RF80, ADC32RF83

www.ti.com

SBAS774A – MAY 2016 – REVISED DECEMBER 2016

Product Folder Links: ADC32RF80 ADC32RF83

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Typical Application (continued)

9.2.1 Design Requirements

9.2.1.1 Transformer-Coupled Circuits

Typical applications involving transformer-coupled circuits are discussed in this section. To ensure good

amplitude and phase balance at the analog inputs, transformers (such as TC1-1-13 and TC1-1-43) can be used

from the dc to 1000-MHz range and from the 1000-MHz to 4-GHz range of input frequencies, respectively. When

designing the driving circuits, the ADC input impedance (or SDD11) must be considered.

By using the simple drive circuit of Figure 262, uniform performance can be obtained over a wide frequency

range. The buffers present at the analog inputs of the device help isolate the external drive source from the

switching currents of the sampling circuit.

Figure 262. Input Drive Circuit

9.2.2 Detailed Design Procedure

For optimum performance, the analog inputs must be driven differentially. This architecture improves common-

mode noise immunity and even-order harmonic rejection. A small resistor (5 Ω to 10 Ω) in series with each input

pin is recommended to damp out ringing caused by package parasitics, as shown in Figure 262.

9.2.3 Application Curves

Figure 263 and Figure 264 show the typical performance at 100 MHz and 1780 MHz, respectively.

SNR = 61.8 dBFS, SINAD = 61.2 dBFS,

HD2 = 71 dBc, HD3 = 75 dBc, SFDR = 71 dBc,

THD = 68 dBc, IL spur = 77 dBc, worst spur = 73 dBc

Figure 263. FFT for 100-MHz Input Frequency

SNR = 57.9 dBFS, SINAD = 57.1 dBFS,

HD2 = 63 dBc, HD3 = 66 dBc, SFDR = 63 dBc,

THD = 60 dBc, IL spur = 79 dBc, worst spur = 77 dBc

Figure 264. FFT for 1780-MHz Input Frequency

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