High-Speed ADC Sets Input Common-Mode Range

Abstract: The input common-mode voltage range (VCM) is important in the design of communication receivers that include baseband-sampling, high-speed ADCs. A VCM is especially important for single-supply, low-voltage circuits with DC-coupled inputs. For single-supply circuits, the input signal that feeds the drive amplifier and ADC should be biased at a DC level well within the VCM range. This arrangement removes a performance hurdle for the amplifier and ADC, because they do not need to maintain low distortion and linearity at 0V. The application note presents a circuit that features the DC-coupled input configuration to the MAX1196 through an RF quadrature demodulator front-end circuit.