OPA GX8138 Replaces AD8138 in Spectrum Analysers

Spectrum analyser in the intermediate frequency signals usually need to be properly amplified to improve signal strength for subsequent processing. Need to use high-performance differential amplifiers to be collected to amplify the IF signal and some of the weak signal enhancement, etc., GXSC low-noise differential amplifier GX8138 has excellent performance indicators, can be used to replace the AD8138 applied in the spectrum analyser.

GX8138 has a high gain bandwidth product, such as -3dB bandwidth up to 300MHz, can effectively amplify the IF signal, to ensure that the signal strength and quality in the transmission and processing process, so that it meets the subsequent circuit on the amplitude of the signal requirements. For some weak input signals, the GX8138 can amplify them to a level that can be processed while maintaining signal integrity and accuracy. Its low noise characteristics help to reduce the noise introduced during the amplification process and improve the signal-to-noise ratio of the signal, thus enabling the spectrum analyser to detect and analyse weak signals more accurately.

The GX8138 can be used as a single-ended to differential amplifier or differential to differential amplifier, is as easy to use as a typical operational amplifier, and greatly simplifies differential signal amplification and driving.The GX8138 utilises both internal common-mode feedback and external gain feedback to provide relatively good gain and phase matching.

With good distortion performance, the GX8138 is an ideal driver for ADCs in communication systems, driving 10-bit to 16-bit converters at higher frequencies. The high bandwidth and IP3 characteristics make it suitable for use as a gain module in IF and baseband signal chains. Excellent detuning and dynamic performance make the device well suited for a variety of signal processing and data acquisition applications. Key features are as follows:

- Adjustable common mode voltage and externally adjustable gain

- Spurious-free dynamic range (SFDR): -91dBc (5MHz input); -81dBc (20MHz input)

-3dB bandwidth: 300MHz (G=+1)

- 0.01% Build-up time: 20ns

- Voltage swing rate: 1000V/μs

- Fast overdrive recovery: 8ns

- Low input voltage noise: 3.5nV/√Hz

- Offset voltage: 0.5mV (typical)

- Wide supply voltage range: +3V to ±5V

- Low power consumption: 130mW(5V)

- 0.1dB gain flatness up to 40MHz

- Available in 8-pin SOIC and MSOP packages