LT6236 datasheet(23/50 Pages) LINER

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LTC2372-16

237216f

For more information www.linear.com/LTC2372-16

Maximizing SNR with a Single-Ended to Differential

Conversion

A single-ended input signal may be converted to a fully

differential signal prior to driving the MUX analog inputs

of the LTC2372-16 to take advantage of the higher SNR

of the LTC2372-16 in the fully differential input range.

The LT6350 ADC driver shown in Figure 9a can be used

to convert a 0V to 4.096V input signal to a fully differential

±4.096V output signal. The RC time constant is larger in

this case to limit the high frequency noise contribution

of the LT6350. This topology provides a 2.5dB increase

in SNR over single-ended operation and achieves the full

data sheet SNR performance of the fully differential input

range of 96dB as shown in the FFT plot in Figure 9b. The

maximum supply current of 10.4mA makes the LT6350 a

good companion to the low power LTC2372-16.

Figure 9a. LT6350 Converting a 0V to 4.096V Single-Ended Signal to a ±4.096V Fully Differential Signal

applicaTions inForMaTion

Figure 9b. 32k Point FFT fSMPL = 500ksps,

fIN = 1kHz for Circuit Shown in Figure 9a

Maximizing SNR for Eight Single-Ended Inputs Using

a Shared Amplifier Between MUXOUT+/– and ADCIN+/–

While converting a single-ended signal to a fully differ-

ential signal offers the benefit of higher SNR, two input

channels are required per single-ended input, leading to

a reduced number of single-ended input signals that can

be interfaced to the LTC2372-16. Performing the sin-

gle-ended to differential conversion using the LT6237

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7

COM

MUX CHANNELS

CH0 AND CH1

SELECTED

MUXOUT+/–

SHORTED TO

ADCIN+/–

LTC2372-16

16-BIT ADC CORE

–

237216 F09a

3300pF

LT6350

VCM = 2.048V

4.096V

OUT2

–

3300pF

–

4.096V

OUT1

4.096V

V+

V–

+–

RINT

3300pF

SNR = 96dB

THD = –108.2dB

SINAD = 95.8dB

SFDR = 110.5dB

FREQUENCY (kHz)

100

150

200

250

–180

–160

–140

–120

–100

–80

–60

–40

–20

237216 F09b

LT6236 Datasheet(PDF) 23 Page - Linear Technology

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