Replacing the ADS4449 with the GXSC ADC in Active Antenna Arrays

Active antenna arrays operate on the principles of independent transmission and reception by each element, multi-channel synchronous sampling, and digital beamforming. By having multiple antenna elements receive spatial RF signals in parallel and utilizing backend digital algorithms, they achieve beam directional focusing, interference suppression, and multi-user MIMO multiplexing. These arrays offer the advantages of wide coverage, high spectrum utilization, and strong interference resistance.

Active antenna units feature built-in four-channel intermediate frequency (IF) acquisition. GXSC’s four-channel 14-bit analog-to-digital converter (ADC) can simultaneously acquire RF signals from multiple array elements and, in conjunction with beamforming chips, perform digital beamforming. It supports the design of miniaturized RF front-ends for large-scale arrays, fully meeting operators’ requirements for lightweight base station equipment.

Each channel of the GXSC ADC employs a multi-stage, differential pipelined architecture for its ADC core and integrates output error correction logic. Each ADC features high bandwidth and supports a variety of user-selectable input ranges. The ADC integrates a duty cycle correction circuit to stabilize the duty cycle of the internal clock signal, ensuring consistently excellent conversion performance. The ADC conversion data is output directly via two pairs of cross-coupled, multi-channel multiplexed 14-bit LVDS-level interface circuits.

GXSC ADC Product Advantages:

Compatible with the reference model ADS4449

Four-channel 250 MSPS

Low power consumption; no heat sink required

Built-in ADC duty cycle stabilizer (DCS)

Internal ADC reference voltage source

Single 1.8 V power supply

Programmable analog input range

Programmable swing LVDS output

Peak-to-peak input voltage range: 1.4 Vpp to 2.0 Vpp, typical: 1.75 Vpp

Supports 1.8V or 3.3V serial four-wire SPI interface control

Flexible power-saving and power-down modes

Available in a plastic BGA144 package with an operating temperature range of -55°C to +125°C.

Quiescent Performance: DNL: D0.75/+0.75 LSB, INL: 0.40/+4.0 LSB

Differential Analog Input Bandwidth: 400 MHz

Dynamic Performance:

- fin = 90 MHz, ENOB = 11.4 bits, SNDR = 70.3 dBFS, SNR = 70.6 dBFS

-fin = 140 MHz, ENOB = 11.2 bits, SNDR = 69.1 dBFS, SNR = 69.5 dBFS

-fin = 220 MHz, ENOB = 11.2 bits, SNDR = 69.2 dBFS, SNR = 69.4 dBFS

-fin=350 MHz, ENOB=10.6 bits, SNDR=65.8 dBFS, SNR=66.1 dBFS

This domestically produced analog-to-digital converter allows the chip to be flexibly set to power-down mode according to application requirements, significantly reducing power consumption. Programming for configuration and control is performed via a four-wire SPI serial interface.