Application of GX9245 as a Replacement for AD9245 in Spectrum Analyzers

Spectrum analyzers are the primary devices used for detecting and analyzing the frequency components of signals. From signal debugging in 5G communication base stations to electromagnetic compatibility testing during the development of electronic products, the performance of spectrum analyzers directly impacts the accuracy and efficiency of test results. The AD9245 is a widely used high-speed analog-to-digital converter in traditional spectrum analyzers, but the demand for domestic alternatives is growing increasingly urgent. This paper primarily introduces the technical solution for replacing the AD9245 with the GX9245, providing a feasible alternative for the key components of spectrum analyzers.

Spectrum analyzers require precise resolution of amplitude and phase information for signals of different frequencies. The GX9245 adopts a multi-stage differential pipeline architecture and is a single-channel 14-bit 80 MSPS analog-to-digital converter. At an 80 MHz sampling rate, the GX9245 achieves a signal-to-noise ratio of 72.8 dB and a spur-free dynamic range of 85 dB. DC specifications include ±1 LSB INL (typical), ±0.25 LSB DNL (typical), and no missing codes. Its high-speed sampling fully meets the dynamic signal capture requirements of spectrum analyzers.

The GX9245 employs advanced low-noise design technology to effectively reduce self-generated noise, with an input reference noise as low as 0.96 LSB RMS. Additionally, the GX9245 incorporates a high-performance sampling and holding circuit and an on-chip reference voltage source, powered by a 3V analog power supply. A separate output power supply can drive logic circuits operating at 2.1V to 3.6V. Its key performance features are as follows:

• 3V power supply

• Flexible input range: 1VP-P to 2VP-P

• 2.1V to 3.3V output power supply

• Low power consumption: 66mW (20MSPS); 218mW (80MSPS)

• 80MHz sampling, 30.5MHz input:  

   Signal-to-noise ratio (SNR): 72.83dB  

   Spurious-free dynamic range (SFDR): 85.62dB

• Differential non-linearity (DNL): ±0.25 LSB (typical)

• Input reference noise: 0.96 LSB RMS

• On-chip reference voltage source and sample-and-hold circuit