RT1025

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DS1025-01

July

2022

20

PPG Channel - Dynamic Power Down Mode : PRF = 64 to 4096 SPS and duty = 1.5 to 25%

Phase1 SAMPLED1

Phase2 SAMPAMB1

Phase3 SAMPLED2

Phase4 SAMPAMB2

Phase1 CONVLED1

Phase2 CONVAMB1

Phase3 CONVLED2

Phase4 CONVAMB2

ADC RESET

ADC / FE PWD

1/PRF

PPG

TX signal

Ambient

PPG1

PPG2

LED1 (N)

LED2 (N)

AMB1 (N) AMB2 (N)

LED1 (N+1)

AMB1 (N+1) AMB2 (N+1)

LED2 (N+1)

ECG Channel

Below figure shows show the analog/digital parts of

ECG system. The ECG channel supports two-electrode

(2E) mode and right leg drive (RLD) mode, and acts as

a buffer between human and circuit. It integrates a

programmable gain amplifier (PGA), a right leg drive

amplifier, and a 24-bit sigma-delta analog-to-digital

converter (ADC) to sense and digitize the ECG signal.

The PGA is a differential input/differential output, and

has seven gain settings (1, 2, 3, 4, 6, 8, and 12). The

sampling frequency of ECG ADC is adjustable from

64Hz to 4096Hz. There are two extra samples (data = 0)

when doing first time sample ECG.

ECG

PGA

ECG

ADC

CIC

FILTER

INP_ECG

INN_ECG

PGA_Gain

ECG

SRAM

VRLD