Capacitance multiplier circuit

A transimpedance amplifier (TIA) circuit, comprising:

• an amplifier coupled between a pair of RC filters, each filter configured to filter a signal generated by the amplifier;
• a pair of first output branches, each coupled to a respective filter output;
• and
• a pair of second output branches, each in parallel with a corresponding first output branch,
• wherein each first output branch is configured to sense an output current (iout) through its corresponding filter, and each second output branch is configured to multiply the sensed iout as a function of an integer multiplier K, wherein K is greater than 1 and configured to feed back the multiplied iout to the respective filter inputs to realize a larger effective capacitance in the TIA circuit.

An apparatus including a capacitance multiplier circuit, comprising:

• a filter having a resistor (R) in parallel with a capacitor (C);
• a first signal path coupled to a filter output;
• and
• a second signal path coupled to an input to the filter,
• wherein a current output through the filter (iout) is split between the two paths, sensed in the first path and multiplied in the second path, the multiplied current being fed back from the second path to the filter input to increase the effective capacitance of the capacitor (C).

A method for capacitance multiplying comprising:

• sensing a current (iout) from a filter in a first path, wherein the filter includes an input coupled to a resistor (R) in parallel with a capacitor (C);
• multiplying the sensed current (iout) in a second path by a multiplier K, wherein K is greater than 1, and wherein the second path is in parallel with the first path;
• and
• feeding back the multiplied current from the second path to the filter input to increase the effective capacitance of capacitor (C).

An apparatus for capacitance multiplying comprising:

• means for sensing a current (iout) from a filter in a first path, wherein the filter includes an input coupled to a resistor (R) in parallel with a capacitor (C);
• means for multiplying the sensed current (iout) in a second path by a multiplier K, wherein K is greater than 1, and wherein the second path is in parallel with the first path;
• and
• means for feeding back the multiplied current from the second path to the filter input to increase the effective capacitance of capacitor (C).