Multiplexer and Pre-filter

Multiplexers of INHMUX, INLMUX, VRHMUX, and VRLMUX can select the inputs of FTIN, INL, VRH, and VRL

to the ADC. Where FTIN and INL are outputs. These two signals will go through a RC pre-filter and then are

connected to the fully differential inputs, INH and INL, of the ADC. They can also bypass the RC filter by control

of BPFTR and FTR, and are connected to the ADC directly. The control registers control all the selections. The

control registers and the selections are shown in Tables 9, 10, 11, and 12.

Table 9. Setting of INH Multiplexer

Name

SMV

SGND

ADRF

ACBO

CMPH

AX2

AX3

SINH

0000

0011

0111

1000

1001

1011

1100

Table 10. Setting of INL Multiplexer

Name

SGND

AX2

AX3

SINL

000

101

110

Table 11. Setting of VRH Multiplexer

Name

ADRF

SMV

AX3

SRFH

00

10

11

Table 12. Setting of VRL Multiplexer

Name

AGND

SMV

AX3

SRFL

000

011

100

Multiplexer CMPH (CMPHMUX) can select signals to op amp ACBUF. The control registers and selections are

shown in Table 13.

Table 13. Setting of CMPH Multiplexer

Name

SMV

ADRF

AX2

SGND

AGND

VRH

VRL

SCMPH

0000

0011

0101

1100

1101

1110

1111

Operation Amplifier (Op Amp)

1) ACBUF Op Amp

Op amp of ACBUF, control switch of ACDIV and the external resistors can form a gain loop.