SBAS745B December 2015 – January 2023 ADS54J66
PRODUCTION DATA
The ADS54J66 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 very 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, thus resulting in a more constant SFDR performance across input frequencies.
The common-mode voltage of the signal inputs is internally biased to 1.9 V using 600-Ω resistors which allows for ac coupling of the input drive network. Each input pin (INP, INM) must swing symmetrically between (VCM + 0.475 V) and (VCM – 0.475 V), resulting in a 1.9-VPP (default) differential input swing. The input sampling circuit has a 3-dB bandwidth that extends up to 900 MHz.