GXSC AFE Replaces ADS1283/ADS1284 for Seismic Monitoring Applications

Seismic monitoring utilizes the propagation law of seismic waves excited by way of artificial sources within elastic different strata to explore the geological situation underground. Through the node equipment to record and analyze the characteristics of the data, can more accurately determine the depth and morphology of these interfaces, to determine the lithology of the strata. Accurate monitoring of seismic activity and timely issuance of early warnings are essential for reducing earthquake disaster losses. In the seismic monitoring system, high-performance AFE plays a key role.

The GXSC high-performance AFE is an extremely high-performance, single-chip, high-resolution analog-to-digital converter that meets the stringent requirements of seismic monitoring equipment. The dual-channel multiplexer can be used for signal measurement and ADC test signal input switching. The signal test mode can test the chip noise floor by shorting the internal inputs for easy runtime equipment diagnostics.The PGA features high input impedance and low noise for direct connection to geophones and hydrophones.

A dual-channel multiplexer, a low-noise programmable gain amplifier (PGA), a multi-order sigma-delta modulator, and digital filter combinations are included internally.

The AFE has excellent noise, linearity and distortion performance. The modulator output is filtered and extracted by an on-chip digital filter to produce a set-rate sample data output. The digital filters provide data rates from 250 to 4000 SPS. The high-pass filter (HPF) has a programmable turn frequency and bypass mode. On-chip gain and offset calibration registers support calibration of the sampled data. The synchronization input pin controls the timing of the ADC conversion. The shutdown input pin places the ADC in power-down power-saving mode.

AFE Application Characteristics:

- High Resolution Mode.

-18mW (PGA=1/2/4/8)

-129dB DNR (250SPS, PGA=1)

- Typical Distortion THD: -122dB

- Common Mode Rejection Ratio CMRR: ≥110dB

- Dual Channel Multiplexer

- Hardware over-range detection

- Digital Filter: SINC+FIR+IIR (optional)

- Filters with linear or minimum phase options

- Bypassable programmable high pass filter HPF

- Sample synchronization control inputs

- Enhanced electrostatic and analog input pulse protection

- Offset and gain calibration

- Programmable differential amplifier: 1/2/4/8/16/32/64x voltage amplification

- Digital supply: 3.3V or 1.8V; analog supply: single 5V or ±2.5V