A Sigma-Delta analog-to-digital converter (ADC) having a direct time filter (DTF) in the feed-back path of the Sigma-Delta loop of the ADC. A Sigma-Delta ADC having a modified DTF in the feed-back path of the Sigma-Delta loop of the ADC is also disclosed. The ADC may also include a noise reduction block that splits an incoming RF signal, samples one of the split signals with a primary ADC, corrects for gain and delay inaccuracies and inverts the signal, applies the inverted signal to a primary digital-to-analog converter (DAC), combines the output of the DAC with the second split signal, which is then applied to a difference ADC.