Data Sheet

AD4020

Rev. A | Page 21 of 36

REF

VDD

VIO

GND

IN+

IN–

SDI

SCK

SDO

CNV

AD4020

1.8V TO 5V

+IN

–IN

R4

1kΩ

DIFFERENTIAL

AMPLIFIER

R1

1kΩ

V–

AMP

0

1.8V

10µF

R3

1k

Ω

V+

–OUT

+OUT

R2

1kΩ

R

R

0.1µF

HOST

SUPPLY

C

C

REF

V+ = +5V

LDO

10kΩ

10kΩ

4.096V

0.1µF

0.1µF

3-WIRE/4-WIRE

INTERFACE

DIGITAL HOST

(MICROPROCESSOR/

FPGA)

Figure 36. Typical Application Diagram for Single-Ended to Differential Conversion with a Fully Differential Amplifier

Single to Differential Driver

For applications using a single-ended analog signal, either

bipolar or unipolar, the ADA4940-1 single-ended to differential

driver allows a differential input to the device. The schematic is

shown in Figure 36.

High Frequency Input Signals

The AD4020 ac performance over a wide input frequency range

is shown in Figure 37 and Figure 38. Unlike other traditional

SAR ADCs, the AD4020 maintains exceptional ac performance

for input frequencies up to the Nyquist frequency with minimal

performance degradation.

102

96

90

100

92

94

98

88

17.0

15.5

16.5

14.5

15.0

16.0

14.0

1k

100k

10k

900k

INPUT FREQUENCY (Hz)

ENOB

SINAD

SNR

Figure 37. SNR, SINAD, and ENOB vs. Input Frequency

–90

–105

–95

–115

–110

–100

–120

120

105

115

95

100

110

90

1k

100k

10k

900k

INPUT FREQUENCY (Hz)

THD

SFDR

Figure 38. THD and SFDR vs. Input Frequency