Replacing the AD7626: GX7626 16-Bit 10MSPS ADC for Spectrum Analysis Applications

A spectrum analyzer is an instrument used to study the spectral structure of electrical signals. Its basic task is to resolve weak signal components in the presence of noise and distortion. This task imposes dual constraints on the analog-to-digital converter: a sufficiently high sampling rate to cover the target frequency band, and sufficiently low noise and distortion to maintain dynamic range. The GX7626 16-bit 10MSPS SAR analog-to-digital converter can replace the AD7626 pin-to-pin in spectrum analysis applications.

The GX7626 SAR architecture provides good noise performance and linearity. The GX7626 integrates a high-speed 16-bit sampling ADC, an internal conversion clock, and an internal buffered reference source. On the rising edge of CNV±, the device samples the voltage difference between the IN+ and IN− pins. The voltages on these pins swing within the range of 0V to REF and its inverse, with a reference voltage of 4.096V, which can be generated internally or provided externally. All conversion results are obtained through an LVDS self-clocked serial interface or an echo-clock serial interface, thereby reducing external hardware connections.

GX7626 Features:

Throughput rate: 10MSPS

Signal-to-noise ratio (SNR): 82dB

Linearity (SFDR): 101dB

Integral nonlinearity (INL): ±2LSB

Differential nonlinearity (DNL): ±0.5LSB

Power consumption: 277mW

Reference voltage: 4.096V

Serial LVDS interface

Self-clocked mode

Echo-clock mode

Conversion control (CNV signal) selectable via LVDS or CMOS

32-pin 5mm×5mm QFN package

Operating temperature range: −40°C to +85°C

Summary: The value of the GX7626 in spectrum analysis applications lies not in pursuing the highest sampling rate, but in providing a high-dynamic-range digitization front end through the inherent linearity and latency-free characteristics of the SAR architecture, combined with 10MSPS throughput sufficient to cover the intermediate frequency band.