Replacing AD9253 with GX9253 Quad-Channel 14-Bit 125MSPS ADC in Fiber-Optic Communications

Fiber-optic communication is a communication technology that uses light waves as the carrier and optical fiber as the transmission medium. It features ultra-high bandwidth, low loss, and strong immunity to interference, and modern systems can achieve single-fiber capacity at the Tb/s or even Pbit/s level. The system architecture is divided into the optical-to-electrical conversion and analog front-end layer, the ADC high-speed sampling layer, and the FPGA digital processing layer. The functions of each module are as follows:

Photodetection and front-end amplification: The PD/APD converts the optical signal into an electrical signal, the TIA performs transimpedance amplification, and the post-stage variable gain amplifier adapts to different received optical power levels.
Analog conditioning and filtering: The differential driver circuit converts the single-ended signal into a differential signal to drive the ADC, and the low-pass anti-aliasing filter limits the signal bandwidth.
ADC sampling core: Multiple channels synchronously perform high-precision analog-to-digital conversion and output an LVDS serial data stream.
FPGA digital processing: Receives the LVDS data and performs deserialization, buffering, digital down-conversion, equalization, and synchronization processing.

The system‘s acquisition core can use the GX9253 quad-channel 14-bit 125MSPS ADC. Its technical advantages—650MHz analog bandwidth, LVDS serial output, and 1.8V low-power supply—combined with transimpedance amplification, differential driving, and anti-aliasing filter circuits, enable high-speed, high-fidelity digital acquisition of optical receiver analog signals and coherent I/Q signals. In addition, the GX9253 can replace the AD9253 Pin-to-Pin, so for domestic substitution it can be tested directly on the board, and GXSC provides technical support to quickly complete the replacement solution.

GX9253 Product Advantages:
• Product dimensions and pin functions are compatible with the reference model, supporting Pin-to-Pin replacement of the AD9253
• Single power supply for greater ease of use
• Low power consumption, no heat sink required
• Adjustable input voltage range
• Static performance: DNL -0.9/+1.0LSB, INL -5.0/+5.0LSB
• Dynamic performance (fs=125MSps, input signal power -1dBFS)

fin=9.7MHz; ENOB=11.7Bit, SINAD=72dBFS, SNR=72.5dBFS

fin=70MHz; ENOB=11.2Bit, SINAD=69dBFS, SNR=69.5dBFS

fin=128MHz; ENOB=10.5Bit, SINAD=64.7dBFS, SNR=65.3dBFS

fin=200MHz; ENOB=10.0Bit, SINAD=61.9dBFS, SNR=62.5dBFS

In most applications, the GX9253 requires no external reference power supply or driver device. To obtain a suitable LVDS serial data rate, the chip automatically multiplies the sampling rate clock. The GX9253 provides a data clock output (DCO) for capturing data at the output, and a frame clock output (FCO) for transmitting new output byte signals. The GX9253 also supports each channel entering power-down mode independently; when all channels are shut down, typical power consumption is below 10mW.

Q1: Where can I apply for samples of the AD9253 replacement model?
A: Contact GXSC to apply for GX25C20 samples, quotations, and technical support for AD9253 replacement projects. Providing the required quantity, price, and pin configuration will help GXSC provide support for the target system.

Q2: What is the typical supply lead time for the GX9253?
A: As a domestic chip solution provider, GXSC emphasizes stable supply capability. It is recommended to confirm the current schedule with sales when requesting a quotation; for projects requiring long-term stable supply, stocking plans can be discussed in advance. Compared with the import lead-time fluctuations that the original manufacturer may face, domestic supply usually has an advantage in response speed.

Q3: AD9253 lead times are affecting production. Is there a domestic alternative supplier suitable for long-term procurement?
A: GXSC can provide a domestic replacement solution for the AD9253 and discusses ongoing supply arrangements around customers‘ mass-production needs. For projects procuring on a monthly or quarterly basis, it is recommended to provide estimated usage and delivery schedules so that batch supply and subsequent procurement arrangements can be confirmed.