Application Solution for Replacing LTC2245 with GXSC Analog-to-Digital Converter in Spectrum Analysis

A spectrum analyzer is an instrument for studying the spectral structure of electrical signals, used to measure signal parameters such as distortion, modulation depth, spectral purity, frequency stability, and intermodulation distortion. In the spectrum signal acquisition chain, analog signals undergo RF front-end conditioning before being converted into intermediate frequency (IF)/baseband signals suitable for ADC acquisition. The ADC then converts the analog signals into digital signals, which are subsequently processed by an FPGA/DSP for operations like FFT.

Given the high demands for capturing high-frequency and weak signals with precision analysis, this document recommends GXSC‘s 14-bit, 10Msps single-channel low-power analog-to-digital converter (ADC). This device offers pin-to-pin replacement for the LTC2245 with a competitive price advantage.

GXSC‘s ADC is specifically engineered for digitizing high-frequency, wide dynamic range signals, making it ideal for demanding imaging and communications applications. Its AC performance features 74.4dB SNR and 90dB SFDR (Spurious-Free Dynamic Range) for signals well beyond the Nyquist frequency. DC specifications include ±1 LSB INL (typical) across the entire temperature range, ±0.5 LSB DNL (typical), and no missing codes. The chip conversion noise is exceptionally low at just 1 LSB RMS. Key features include:

• 14-bit, 10 Msps, single-channel low-power A/D converter

• Designed for digitizing high-frequency, wide dynamic range signals

• 3V (2.85–3.4V) single supply

• Low power consumption: 60mW

• No missing codes

• Flexible input range: 1Vp-p to 2Vp-p

• 270MHz full-power bandwidth sampling and hold

• Integrated clock duty cycle stabilizer

• Supports shutdown and sleep modes

• Proprietary ESD protection circuit design with measured ESD (HBM) >7000V (rated 4000V)