2.2 Unraveling the practical mysteries behind RF converter front-ends
Industrial TI Tech Days session
Let’s face it: high-speed ADCs operate differently. Their analog inputs are voltage-input-sensitive devices that leave RF engineers scratching their heads about how to properly design the analog input front-end interface. Adding to this confusion, analog input interfaces are typically differential by nature and host a time-varying type of input impedance as the internal sampling switch opens and closes at the speed of light. This input impedance is thought to be a real resistive value across the ADC’s input bandwidth, but when plotted on a Smith chart, the trace curve just goes around and around. In this presentation, we will uncover some of the details of front-end tradeoffs that typically wreak havoc and give rise to poor performance.