Second order loop filter and multi-order delta sigma modulator including the same

A second order loop filter comprising:

• an operational amplifier comprising a first input, a second input, a first output and a second output;
• a first resistor connected between the first input and a first node;
• a second resistor connected between the first output and the first node;
• a third resistor connected between the first input and a first input signal;
• a fourth resistor connected between the second input and a second node;
• a fifth resistor connected between the second output and the second node;
• a sixth resistor connected between the second input and a second input signal;
• a first capacitor connected between the first node and the second node;
• a second capacitor connected between the second output and the first node;
• a third capacitor connected between the first input and the first output;
• a fourth capacitor connected between the first output and the second node;
• and
• a fifth capacitor connected between the second input and the second output,
• wherein the first and second inputs comprise differential inputs, the first and second outputs comprise differential outputs, and the first and second input signals comprise differential input signals.

A multi-order delta-sigma modulator comprising:

• a second order loop filter (LF) for integrating a difference between an input signal and an analog signal, and outputting the integrated signal;
• a quantizer for quantizing a signal output from the second order LF, and outputting the quantized signal;
• and
• a digital to analog converter (DAC) for converting the signal output from the quantizer into an analog signal, and outputting the analog signal,
• wherein the second order LF comprises:
• an operational amplifier comprising a first input, a second input for receiving a differential input of the first input, and an output;
• an inverter for inverting a signal output from the output of the operational amplifier, and outputting the inverted signal;
• a first resistor connected between the first input and a first node;
• a second resistor connected between the output of the operational amplifier and the first node;
• a third resistor connected between the first input and an input signal;
• a first capacitor connected between the second input and the first node;
• a second capacitor connected between the output of the operational amplifier and an output of the inverter;
• and
• a third capacitor connected between the output and the first input of the operational amplifier,
• wherein the second input is connected to a ground voltage.