Continuous-time delta-sigma modulator, integrated circuit and method therefor

An integrated circuit comprising a continuous-time delta-sigma modulator (CTDSM), the CTDSM comprising:

• an operational transconductance amplifier (OTA) having an input port configured to receive an analog input signal and an output port;
• an input low pass filter network comprising at least one input resistor, R1, at least one first shunt capacitor, C1, and at least one feedback resistor, Rdac, each connected to the input port of the OTA;
• an output filter network comprising a shunt second resistor, R2, in parallel to a second shunt capacitor, C2, and coupled to the output port of the OTA;
• a quantizer connected to the output filter network and having an output connected to the input port of the OTA via the at least one feedback resistor, Rdac;
• and
• wherein the input port and the output port of the OTA are connected by a third feedforward-feedback capacitor, C3, arranged to provide a positive feedback path around the OTA.

A method of delta-sigma modulation by a continuous-time delta sigma modulator (CTDSM) having a single operational transconductance amplifier (OTA) comprising input port and output port, the method comprising:

• receiving an analog input signal;
• forming an input low pass filter network comprising at least one input resistor, R1, at least one first shunt capacitor, C1, and at least one feedback resistor, Rdac, connected to the input port of the OTA, wherein the analog input signal is arranged to pass through the input low pass filter network;
• forming an output low pass filter network comprising a shunt second resistor, R2, in parallel to a second shunt capacitor, C2, and coupled to the output port of the OTA;
• coupling a quantizer to the output low pass filter network;
• forming at least one negative feedback path from an output of the quantizer to the input port of the OTA via the at least one feedback resistor, Rdac;
• and
• connecting the output port of the single OTA to the input port of the single OTA by a third feedforward-feedback capacitor, C3;
• wherein the input port and the output port of the OTA are connected by the third feedforward-feedback capacitor, C3, arranged to provide a positive feedback path around the OTA.