SLASE67A January 2015 – August 2019 ADS54J54
PRODUCTION DATA.
The ADS54J54 analog signal inputs are designed to be driven differentially. The analog input pins have internal analog buffers that drive the sampling circuit. As a result of the analog buffer, the input pins present a high-impedance input across a wide frequency range to the external driving source, which enables great flexibility in the external analog filter design as well as excellent 50-Ω matching for RF applications. The buffer also helps isolate the external driving circuit from the internal switching currents of the sampling circuit, which results in a more constant SFDR performance across input frequencies.
The common-mode voltage of the signal inputs is internally biased to 2 V using 500-Ω resistors, which allows for AC coupling of the input drive network. Each input pin (INP, INM) must swing symmetrically between (VCM + 0.3125 V) and (VCM – 0.3125 V), resulting in a 1.25-Vpp (default) differential input swing. The input sampling circuit has a 3-dB bandwidth that extends up to 900 MHz.