Combining sampling analog-to-digital converter with continuously integrating analog-to-digital converter

A method of producing a digital signal from an analog signal, comprising:

• receiving an input analog signal at an integrating analog-to-digital converter (ADC) and a high-speed ADC having a higher speed than the integrating ADC, wherein the integrating ADC comprises a digital filter;
• applying a digital filter to output samples of the high-speed ADC to produce filtered samples, the digital filter being matched to an aperture of the integrating ADC determined by the digital filter of the integrating ADC;
• finding differences between the filtered samples and output samples of the integrating ADC to produce error values based on a ratio of a sample rate of the integrating ADC to a sample rate of the high-speed ADC;
• and
• adding the error values to the output samples of the high-speed ADC to produce data samples of the input analog signal.

A circuit, comprising:

• a port connectable to a device under test (DUT) to receive an input signal;
• a first analog-to-digital converter (ADC) coupled to the port to receive the input signal;
• a second ADC coupled to the port to receive the input signal, the second ADC having a higher speed than the first ADC;
• and
• one or more processors configured to:
• apply a digital filter to output samples of the second ADC to produce filtered samples, the digital filter being matched to an aperture of the first ADC determined by a digital filter of the first ADC;
• subtract the filtered samples from output samples of the first ADC to produce differences;
• multiply the differences by a ratio of a sample rate of the first ADC to a sample rate of the second ADC to produce error values;
• and
• add the error values to the output samples of the second ADC to produce data samples of the input signal.

A method, comprising:

• receiving an input analog signal at a first analog-to-digital converter (ADC) and a second ADC having a higher sample rate than the first ADC, wherein the first ADC comprises a digital filter;
• applying a digital filter to output samples of the second ADC to produce filtered samples, the digital filter being matched to an aperture of the first ADC determined by the digital filter of the first ADC;
• finding differences between the filtered samples and output samples of the first ADC to produce error values based on a ratio of a sample rate of the first ADC to a sample rate of the second ADC;
• and
• adding the error values to the output samples of the second ADC to produce data samples of the input analog signal.