Abstract: A fully-differential two-stage operational amplifier circuit is provided, and it includes a first-stage amplification circuit, a second-stage amplification circuit, a common-mode signal acquisition circuit, a common-mode feedback circuit and a bias circuit. The first-stage amplification circuit has a telescopic structure and receives differential input signals INP and INN. The second-stage amplification circuit has a common-source structure and outputs differential output signals OUTP and OUTN. The common-mode signal acquisition circuit receives differential output signals, and outputs an operational amplifier output common-mode signal VCMO. The common-mode feedback circuit outputs common-mode feedback signals VB1 and VB2 to the first-stage amplifier circuit and the second-stage amplifier circuit respectively; The bias circuit outputs a bias voltage VB3 to the first-stage amplifier circuit, and outputs bias voltages VB4 and VB5 to the first-stage amplifier circuit respectively.

Abstract: This invention provides an accurate current mirror circuit in a low voltage headroom applied to common-anode laser drivers, including a reference current detection unit, a tail current source unit, and a control unit. The reference current detection unit generates a bias voltage and a reference voltage according to a reference current from the reference current source; the tail current source unit receives the bias voltage and generate a mirror current accordingly; the control unit receives the reference voltage and an output voltage corresponding to the mirror current and carry out a feedback regulation to the bias voltage accordingly. In this invention, the reference voltage and the output voltage are locked at same level, and then the bias voltage is mirrored to generate the mirror current outputted to the laser, thus avoiding the problem of inaccurate current output caused by the offset of the control unit in the low voltage headroom.

Abstract: This invention provides a multi-bit digitally controlled accurate current source circuit including a reference current detection unit, a voltage buffer unit, a digital logic control unit, a switch array unit, and a current source array unit. The reference current detection unit generates a first bias voltage according to a reference current; the voltage buffer unit receives the first bias voltage, and generate a buffer voltage accordingly; the digital logic control unit receives the buffer voltage, and generate a digital control signal accordingly; the switch array unit receives the digital control signal, and generate on-off signals accordingly; and the current source array unit receives and responds to the on-off signals so as to control turn-on and turn-off of the current sources in the current source array unit. In this invention, by adding only one voltage buffer, a cascode current source if formed, and an area saving accurate current source is realized.

Abstract: This invention provides a multi-bit digitally controlled accurate current source circuit including a reference current detection unit, a voltage buffer unit, a digital logic control unit, a switch array unit, and a current source array unit. The reference current detection unit generates a first bias voltage according to a reference current; the voltage buffer unit receives the first bias voltage, and generate a buffer voltage accordingly; the digital logic control unit receives the buffer voltage, and generate a digital control signal accordingly; the switch array unit receives the digital control signal, and generate on-off signals accordingly; and the current source array unit receives and responds to the on-off signals so as to control turn-on and turn-off of the current sources in the current source array unit. In this invention, by adding only one voltage buffer, a cascode current source if formed, and an area saving accurate current source is realized.

Abstract: This invention provides an accurate current mirror circuit in a low voltage headroom applied to common-anode laser drivers, including a reference current detection unit, a tail current source unit, and a control unit. The reference current detection unit generates a bias voltage and a reference voltage according to a reference current from the reference current source; the tail current source unit receives the bias voltage and generate a mirror current accordingly; the control unit receives the reference voltage and an output voltage corresponding to the mirror current and carry out a feedback regulation to the bias voltage accordingly. In this invention, the reference voltage and the output voltage are locked at same level, and then the bias voltage is mirrored to generate the mirror current outputted to the laser, thus avoiding the problem of inaccurate current output caused by the offset of the control unit in the low voltage headroom.