A common application for the TRF0208-SP is driving a high-speed ADC that has a differential input (such as the ADC12DJ5200-SP or AFE7950-SP). Conventionally passive baluns are used to drive giga-samples-per-second (GSPS) ADCs as a result of the low availability of high-bandwidth, linear amplifiers. The TRF0208-SP is typically configured as a single-ended to differential (S2D) RF amplifier that has excellent bandwidth flatness, gain, and phase imbalance comparable to or exceeding costly passive RF baluns.

Figure 7-1 shows a typical interface circuit for ADC12DJ5200-SP. Depending on the ADC and system requirement, this circuit can be simplified or can be more complex.

Figure 7-1 Interfacing With the ADC12DJ5200-SP

Figure 7-1 shows two sections of the circuit between the driver amp and the ADC: namely, the matching pad (or attenuator pad) and the antialiasing filter. Use small-form-factor, RF-quality, passive components for these circuits. The output swing of the TRF0208-SP is designed to drive these ADCs full-scale, while at the same time not overdrive the ADC. This functionality avoids the need for any voltage limiting device at the ADC.

Figure 7-2 shows a typical interface circuit for the AFE7950-SP, where the TRF0208-SP is the S2D amplifier.

A. AFE matching network – component type (L or C) and values depend on channel (A, B, C, D, FB1, and FB2) and frequency band.

Figure 7-2 Interfacing With the AFE7950-SP