Interfacing the VCA8613 with High-Speed ADCs
The VCA8613 is an 8-channel variable gain amplifier ideally suited for portable and mid-range ultrasound applications. Each channel consists of a Low Noise Amplifier (LNA) and a Variable Gain Amplifier (VGA). The VGA contains two parts: a voltage-controlled attenuator (VCA) and a programmable gain amplifier (PGA). The PGA output feeds directly into an integrated 2-pole low-pass Butterworth filter. This integrated filter prevents the need for an external filter between the VCA and the analog-to-digital converter (ADC). This application report reviews different methods of interfacing the VCA8613 with various ADCs, particularly the ADS512x and ADS527x families.