Shared Operational Transconductance Amplifier Pipelined ADC Incorporating a Sample/Hold Amplifier and Multiple MDAC Stages

In a pipelined ADC having first and second ADC input connections for together receiving a differential input signal, a method comprising:

• a) providing an operational transconductance amplifier (OTA) having a differential input and a differential output, and a first quantizer connection;
• b) for each ADC input connection;
• 1) providing a plurality of input signal sampling capacitors, a first feedback capacitor, a second lead of the feedback capacitor being coupled to second leads of the input signal sampling capacitors;
• 2) coupling a first lead of the feedback capacitor to a first voltage, coupling the second leads of the input signal sampling capacitors to a second common mode voltage, and coupling first leads of the input signal sampling capacitors to a respective one of the ADC input connections;
• 3) decoupling the first leads of the input signal sampling capacitors from the respective one of the ADC input connections and decoupling the second leads of the input signal sampling capacitors from the second common mode voltage;
• 4) coupling the second leads of the input signal sampling capacitors to a respective one of the differential inputs of the OTA and coupling a respective output of the OTA to the first leads of the input signal sampling capacitors and to an input to a first quantizer;
• c) latching an output of the first quantizer;
• and,
• d) for each ADC input connection;
• 1) coupling the first lead of the first feedback capacitor to the output of the OTA, and coupling the first lead of each of the input signal sampling capacitors to a positive or a negative voltage responsive to the output latched in the first quantizer.