Switched capacitor filter circuit having reduced offsets and allowing for offset compensation without a closed feedback loop

An apparatus including a switched capacitor filter circuit having reduced offsets and allowing for offset compensation without a closed feedback loop, comprising:

• a chopper stabilized amplified filter circuit that receives one or more chop control signals, receives and low pass filters an input data signal and provides a low pass filtered signal with an out of band signal frequency component which is at a frequency of said one or more chop control signals and represents an offset and 1/f noise of said chopper stabilized amplified filter circuit, wherein said chopper stabilized amplified filter circuit includes
• a switched capacitor circuit that receives a plurality of switch control signals, and
• a chopper stabilized amplifier circuit, coupled to said switched capacitor circuit, that receives said one or more chop control signals, provides said low pass filtered signal and includes
• an input switching circuit that receives said one or more chop control signals and receives and conveys an input signal with a first plurality of alternating signal polarities,
• a telescopic amplifier circuit, coupled to said input switching circuit, that receives and amplifies said input signal and provides an output signal, and
• an output switching circuit, coupled to said telescopic amplifier circuit, that receives said one or more chop control signals and receives and conveys said output signal with a second plurality of alternating signal polarities,
• wherein said switched capacitor circuit and said chopper stabilized amplifier circuit are operatively coupled together to receive and low pass filter said compensated data signal and provide said low pass filtered signal;
• an output filter circuit, coupled to said chopper stabilized amplified filter circuit, that receives and filters said low pass filtered signal and provides a filtered output data signal in which said out of band signal frequency component is substantially reduced in magnitude;
• an analog-to-digital conversion (ADC) circuit, coupled to said output filter circuit, that receives and converts said filtered output data signal and provides a digital output signal;
• and
• a capacitive feedback circuit, coupled between said output switching circuit and said telescopic amplifier circuit, that receives said plurality of switch control signals and capacitively couples said low pass filtered signal to a portion of said telescopic amplifier circuit;
• wherein as a result of said providing of said low pass filtered signal and said filtered output data signal by said chopper stabilized amplified filter circuit and said output filter circuit, respectively, said digital output signal includes a residual offset within one least significant bit (LSB) of a value of said digital output signal.

An apparatus including a switched capacitor filter circuit having reduced offsets and allowing for offset compensation without a closed feedback loop, comprising:

• a chopper stabilized amplified filter circuit that receives one or more chop control signals, receives and low pass filters an input data signal and provides a low pass filtered signal with an out of band signal frequency component which is at a frequency of said one or more chop control signals and represents an offset and 1/f noise of said chopper stabilized amplified filter circuit;
• an output filter circuit, coupled to said chopper stabilized amplified filter circuit, that receives and filters said low pass filtered signal and provides a filtered output data signal in which said out of band signal frequency component is substantially reduced in magnitude;
• and
• an analog-to-digital conversion (ADC) circuit, coupled to said output filter circuit, that receives and converts said filtered output data signal and provides a digital output signal;
• a digital signal combining circuit, coupled to said switched capacitor filter circuit, that receives and combines said digital output signal and an offset compensation signal and provides a compensated data signal;
• and
• an offset compensation circuit, coupled to said digital signal combining circuit and said switched capacitor filter circuit, that receives said digital output signal, measures said residual offset and provides said offset compensation signal, wherein said offset compensation signal corresponds to said residual offset;
• wherein as a result of said providing of said low pass filtered signal and said filtered output data signal by said chopper stabilized amplified filter circuit and said output filter circuit, respectively, said digital output signal includes a residual offset within one least significant bit (LSB) of a value of said digital output signal.

A method which includes switching a plurality of capacitors to filter a signal with reduced offsets and allowing for offset compensation when filtering said signal without a closed feedback loop, comprising the steps of:

• receiving an input data signal;
• receiving one or more chop control signals, low pass filtering said input data signal and generating a low pass filtered signal with an out of band signal frequency component which is at a frequency of said one or more chop control signals and represents an offset and 1/f noise;
• filtering said low pass filtered signal and generating a filtered output data signal in which said out of band signal frequency component is substantially reduced in magnitude;
• and
• converting said filtered output data signal and generating a digital output signal;
• wherein said digital output signal includes a residual offset within one least significant bit (LSB) of a value of said digital output signal.

A method which includes switching a plurality of capacitors to filter a signal with reduced offsets and allowing for offset compensation when filtering said signal without a closed feedback loop, comprising the steps of:

• receiving an input data signal;
• receiving one or more chop control signals, low pass filtering said input data signal and generating a low pass filtered signal with an out of band signal frequency component which is at a frequency of said one or more chop control signals and represents an offset and 1/f noise, by
• receiving a plurality of switch control signals and switching one or more capacitors,
• chopper stabilizing an amplifier circuit with said one or more chop control signals by
• receiving said one or more chop control signals and receiving and conveying another input signal with a first plurality of alternating signal polarities,
• receiving and telescopically amplifying said another input signal and generating an output signal, and
• receiving said one or more chop control signals and receiving and conveying said output signal with a second plurality of alternating signal polarities;
• integrating said compensated data signal and generating said low pass filtered signal;
• filtering said low pass filtered signal and generating a filtered output data signal in which said out of band signal frequency component is substantially reduced in magnitude;
• converting said filtered output data signal and generating a digital output signal;
• and
• receiving said plurality of switch control signals and capacitively feeding back said low pass filtered signal during said telescopically amplifying of said input signal;
• wherein said digital output signal includes a residual offset within one least significant bit (LSB) of a value of said digital output signal.

A method which includes switching a plurality of capacitors to filter a signal with reduced offsets and allowing for offset compensation when filtering said signal without a closed feedback loop, comprising the steps of:

• receiving an input data signal;
• receiving one or more chop control signals, low pass filtering said input data signal and generating a low pass filtered signal with an out of band signal frequency component which is at a frequency of said one or more chop control signals and represents an offset and 1/f noise;
• filtering said low pass filtered signal and generating a filtered output data signal in which said out of band signal frequency component is substantially reduced in magnitude;
• converting said filtered output data signal and generating a digital output signal;
• combining said digital output signal and an offset compensation signal and generating a compensated data signal;
• and
• receiving said digital output signal, measuring said residual offset and generating said offset compensation signal, wherein said offset compensation signal corresponds to said residual offset;
• wherein said digital output signal includes a residual offset within one least significant bit (LSB) of a value of said digital output signal.