Patent ID: 7567193

Claim:
An electronic circuit comprising: an active integrator including an operational amplifier, the operational amplifier having a first input terminal that receives a summed signal of an input signal and an analog feedback signal, and a second input terminal that receives a reference voltage; and a digital to analog converter (DAC) that converts a digital output of the electronic circuit to an analog signal and provides the analog feedback signal, the DAC comprising: a coupling capacitor; first switches that respectively connect first and second terminals of the coupling capacitor to the reference voltage, in response to a first control signal; at least one current source that generates a current, the current being constant when a voltage difference of two terminals of the current source is greater than a reference value, and the current decreasing when the voltage difference of the two terminals is smaller than the reference value; second switches that selectively connect the second terminal of the coupling capacitor to the current source, in response to a second control signal and the digital output, the second control signal having a non overlapping active period with respect to the first control signal; and a third switch that connects the first terminal of the coupling capacitor to the first input terminal of the operational amplifier, in response to the second control signal, the current source generating the current such that a first time point when the voltage difference is smaller than the reference value is earlier than a second time point when the second control signal is deactivated.