Application of the GXSC ADC as a Replacement for the AD4020 in Automated Test Equipment

Automated test equipment relies on high-precision analog acquisition chains, timing control units, and data processing to achieve automated, high-speed, and standardized testing of the electrical parameters of devices under test. The equipment’s excitation source outputs standard voltage and current excitation signals to the device under test. The analog response signals fed back from the device undergo front-end conditioning, impedance matching, and noise reduction and shaping before being converted into digital form at high speed by a high-precision ADC. The data is then filtered, calibrated, and analyzed to determine parameters, ultimately resulting in the automatic output of pass/fail test results.

The high precision and high speed of the GXSC ADC enable it to accurately acquire test signals, meeting the data accuracy and acquisition speed requirements of automated test equipment. Furthermore, this analog-to-digital converter can replace ADI’s AD4020, allowing for rapid implementation of chip replacement solutions. This domestically produced ADC uses a single power supply (VDD), with the reference voltage (VREF) applied externally and configurable independently of the supply voltage. Its power consumption varies linearly with throughput, and it offers multiple throughput options, including 1.8 MSPS, 1 MSPS, and 500 kSPS.

Key Features of the GXSC ADC:

1. Reduced Input Rebound: Significantly reduces input rebound, lowering the input current to 0.5 μA/MSPS. At 1 MSPS, the sampling phase accounts for ≥77% of the cycle time.

2. Accurate First Conversion: No delay or pipeline delay ensures data timeliness and accuracy.

3. Input Range Compression: Suitable for single-supply operation, eliminating the need for a negative supply to the ADC driver amplifier while retaining the full ADC code range.

4. Input Overvoltage Clamping Protection: Capable of absorbing up to 50 mA of current, protecting the ADC input from overvoltage events, reducing interference with the reference pin, and eliminating the need for external protection diodes.

5. Fast Conversion: Allows for lower SPI clock rates, reducing digital I/O power consumption, expanding digital host options, and simplifying data transmission across digital isolation.

GXSC ADC High-Performance Features:

Wide differential analog input range: ±VREF, with VREF ranging from 2.4 V to 5.1 V.

High resolution: Guaranteed 20-bit resolution with no lost codes.

Excellent dynamic performance: At fIN = 1 kHz and VREF = 5 V, SNR reaches 100.5 dB with THD of -123 dB; at fIN = 900 kHz, SINAD is 89 dB.

Wide oversampling dynamic range: 104 dB at OSR = 2 and 131 dB at OSR = 1024.