Pipeline analog-to-digital converter with common mode following reference generator

A pipeline analog-to-digital converter (ADC) comprising:

• more than one cascaded stages each for resolving at least one bit of an analog voltage, each stage but the last having an analog input, one or more reference voltage inputs, and one or more digital outputs, the analog voltage coupled to the analog input of the first stage, each stage but the last also having an analog output connected to the analog input of the next stage, each stage but the last including an operational amplifier that includes one or more differential amplifiers having an inherent common mode voltage;
• a reference generator to globally generate the one or more reference voltages for a plurality of the stages, the reference generator including means for tracking the inherent common mode voltage of the differential amplifiers such that the generated reference voltages are relative the inherent common mode voltages of the differential amplifiers;
• and
• combining means for combining the digital outputs of the stages and producing the digital representation of the input voltage.

A modem for a wireless local area network to receive and process an analog signal from a radio receiver, the modem including:

• one or more pipeline analog-to-digital converters to digitize the analog signal from the radio receiver to form digitized received signals;
• each pipeline analog-to-digital converter including:
• more than one cascaded stages each for resolving at least one bit of the analog signal, each stage but the last having an analog input, one or more reference voltage inputs, and one or more digital outputs, the analog signal coupled to the analog input of the first stage, each stage but the last also having an analog output connected to the analog input of the next stage, each stage but the last including an operational amplifier that includes one or more differential amplifiers having an inherent common mode voltage;
• a reference generator to globally generate the one or more reference voltages for a plurality of the stages, the reference generator including a circuit to track the inherent common mode voltage of the differential amplifiers such that the generated reference voltages are relative the inherent common mode voltages of the differential amplifiers;
• and
• a combiner having the digital outputs of the stages as input and producing the digitized received signal representation of the input signal;
• and
• a receive signal processor to process the digitized received signals, the processing including demodulating the digitized received signals.