Application of GXSC Single-Channel 14-Bit 80MSPS Analog-to-Digital Converter as a Replacement for AD9245 in Spectrum Analyzers

A spectrum analyzer is primarily used to analyze the spectral characteristics of signals. It can display key parameters such as frequency distribution, power, level, and bandwidth, aiding engineers in assessing signal quality and identifying interference sources. The input signal for a spectrum analyzer is typically an electrical signal, but it can also measure the spectrum of other signals like sound waves and optical waves through appropriate sensors.

The signal acquisition process of a spectrum analyzer requires the analog-to-digital converter (ADC) to possess wideband coverage, high dynamic range capture, and low-distortion conversion capabilities. The GXSC ADC, manufactured using advanced CMOS technology, offers high integration and precise conversion performance, fully meeting the design requirements for spectrum analysis.

The GXSC analog-to-digital converter is a monolithic integrated, single-supply 14-bit ADC featuring a high-performance sample-and-hold amplifier and voltage reference. The chip employs a differential multi-stage pipelined architecture with output error correction logic to deliver 14-bit accuracy and ensure no missing codes across the full temperature range, maintaining stable spectral resolution capability.

The broadband fully differential SHA supports multiple selectable input ranges and wide input common-mode ranges, including single-ended applications. It is suitable for multiplexed systems that switch full-scale voltage levels in continuous channels, as well as for sampling single-channel inputs at frequencies far above the Nyquist rate. A single-ended clock input controls all internal conversion cycles, while the duty cycle stabilization circuit (DCS) compensates for clock duty cycle variations while maintaining excellent ADC overall performance. The digital output data is represented in offset binary or two‘s complement format, with an overrange (OTR) signal indicating input overflow conditions, which, combined with the most significant bit, determines whether the overflow is low or high.

Advantages of GXSC Analog-to-Digital Converter Products:

The plastic QFN32 package is compatible with the imported product AD9245.

Single-channel 20MSPS/40MSPS/65MSPS/80MSPS

Integrated on-chip voltage reference and sample-and-hold circuit

Low power consumption: 210mW@80MSPS

Input signal amplitude: 1Vpp to 2Vpp

Offset binary or two‘s complement data format

On-chip integrated clock duty cycle stabilization circuit

Flexible energy-saving power-off mode

Static performance: DNL: 0.5/+0.5 LSB, INL: -2.0/+2.0 LSB

Differential analog input bandwidth: 500MHz

Dynamic performance:

-fin=5MHz，ENOB=11.3Bit,SNDR=70.0dB,SNR=71.0dB

-fin=70MHz，ENOB=11.1Bit,SNDR=69.0dB,SNR=69.5dB

-fin=100MHz，ENOB=10.7Bit,SNDR=66.5dB,SNR=67.0dB