Elimination of dummy detector on optical detectors using input common mode feedback
View Patent ↗A voltage reference forces a constant voltage at the inputs to an amplifier, thereby negating a need for a dummy detector on the non-active input of the amplifier.
1. A circuit to amplify an electrical signal comprising:
a photo-detector to provide an input signal;
a first amplifier to receive an input signal from the photo-detector and to amplify the input signal to form an output signal, the first amplifier comprising an active input to receive the input signal and a non-active input; and
a second amplifier to force a constant voltage at the active and non-active input of the first amplifier, thereby negating a need for a dummy detector on the non-active input of the first amplifier;
wherein the second amplifier maintains an input common mode voltage at an approximately constant level.
2. The circuit of claim 1 , wherein the photo-detector comprises a photo diode.
3. A circuit to amplify an electrical signal comprising:
a photo-detector to provide an input signal;
a first amplifier to receive an input signal from the photo-detector and to amplify the input signal to form an output signal, the first amplifier comprising an active input to receive the input signal and a non-active input; and
a second amplifier to force a constant voltage at the active and non-active input of the first amplifier, thereby negating a need for a dummy detector on the non-active input of the first amplifier;
further comprising a reference voltage, V reference, to provide a reference voltage to a non-inverting input of the second amplifier.
4. The circuit of claim 3 , wherein the second amplifier senses input common mode voltage of the first amplifier to determine an output signal to force a constant voltage at the active and non-active inputs of the first amplifier.
5. A circuit to amplify an electrical signal comprising:
a photo-detector to provide an input signal;
a first amplifier to receive an input signal from the photo-detector and to amplify the input signal to form an output signal, the first amplifier comprising an active input to receive the input signal and a non-active input; and
a second amplifier to force a constant voltage at the active and non-active input of the first amplifier, thereby negating a need for a dummy detector on the non-active input of the first amplifier;
wherein the first amplifier is a transimpedance amplifier.
6. The circuit of claim 1 , wherein the output of the first amplifier is used in a laser-based device.
7. The circuit of claim 6 , wherein the laser-based device is a compact disc (CD) drive.
8. The circuit of claim 6 , wherein the laser-based device is a digital versatile disc (DVD) drive.
9. The circuit of claim 3 , wherein the photo-detector comprises a photo diode.
10. The circuit of claim 5 , wherein the photo-detector comprises a photo diode.
11. The circuit of claim 3 , wherein the output of the first amplifier is used in a laser-based device.
12. The circuit of claim 5 , wherein the output of the first amplifier is used in a laser-based device.
13. a circuit comprising:
a photo-detector;
a transimpedance amplifier operably connected to the photo-detector; and
a second amplifier having a first input being the input common mode voltage of the transimpedance amplifier and a second input being a reference voltage, the output of the second amplifier providing feedback to the transimpedance amplifier.
14. The circuit of claim 12 , wherein the second amplifier drives the input common mode voltage of the transimpedance amplifier to an approximately constant level.
15. The circuit of claim 12 , wherein the output of the first amplifier is used in a laser-based device.
16. The circuit of claim 15 , wherein the laser-based device is a compact disc (CD) drive.
17. The circuit of claim 15 , wherein the laser-based device is a digital versatile disc (DVD) drive.