Low noise frontends for lidar receiver and methods for controlling the same comprising a multiplexing circuit for selectively connecting each photodetector to a shared amplifier
An optical signal detection system includes a plurality of photodetectors configured to detect optical signals reflected from an environment surrounding the optical signal detection system and convert the optical signals into electrical signals. The optical signal detection system also includes an amplifier coupled to the plurality of photodetectors. The amplifier is shared by the plurality of photodetectors and configured to generate an output signal by amplifying an individual electrical signal converted by a corresponding photodetector. The optical signal detection system further includes a multiplexing circuit configured to selectively establish a connection between one of the plurality of photodetectors and the amplifier to amply the electrical signal converted by that photodetector.
1. An optical signal detection system, comprising:
a plurality of photodetectors configured to detect optical signals reflected from an environment surrounding the optical signal detection system and convert the optical signals into electrical signals;
an amplifier coupled to the plurality of photodetectors, wherein the amplifier is shared by the plurality of photodetectors and configured to generate an output signal by amplifying an individual electrical signal converted by a corresponding photodetector; and
a multiplexing circuit configured to selectively establish a connection between one of the plurality of photodetectors and the amplifier to amplify the electrical signal converted by that photodetector.
2. The optical signal detection system of claim 1 , wherein the amplifier comprises a plurality of input branches arranged in parallel, each of the plurality of input branches being coupled to one of the plurality of photodetectors.
3. The optical signal detection system of claim 2 , wherein the multiplexing circuit comprises a plurality of switches, at least one of the plurality of switches is arranged in one of the plurality of input branches and configured to control the connection between one of the plurality of photodetectors and the amplifier.
4. The optical signal detection system of claim 3 , wherein the at least one of the plurality of switches is connected in series with an input transistor configured to couple one of the plurality of photodetectors to the amplifier.
5. The optical signal detection system of claim 3 , wherein the at least one of the plurality of switches comprises an N-type metal-oxide-semiconductor field-effect transistor or a P-type metal-oxide-semiconductor field-effect transistor.
6. The optical signal detection system of claim 2 , wherein the plurality of input branches are connected to a low-impedance node of the amplifier.
7. The optical signal detection system of claim 1 , wherein the electrical signals comprise at least one of a voltage signal or a current signal.
8. The optical signal detection system of claim 1 , comprising:
a feedback network comprising a plurality of feedback branches connected in parallel, at least one of the plurality of feedback branches comprising a pair of switches connected in series, wherein an output terminal of the at least one of the photodetectors is connected between the pair of switches.
9. The optical signal detection system of claim 8 , wherein the pair of switches are configured to:
feedback the output signal to the output terminal of the at least one of the photodetectors when the multiplexing circuit establishes the connection between the at least one of the photodetectors and the amplifier; and
ground the output terminal of the at least one of the photodetectors when the multiplexing circuit does not establish the connection between the at least one of the photodetectors and the amplifier.
10. A method of processing optical signals, comprising:
detecting, by a plurality of photodetectors, the optical signals reflected from an environment surrounding an optical signal detection system;
converting, by the plurality of photodetectors, the optical signals into electrical signals;
selectively establishing, by a multiplexing circuit, a connection between one of the plurality of photodetectors and an amplifier, wherein the amplifier is coupled to and shared by the plurality of photodetectors; and
generating, by the amplifier, an output signal by amplifying an individual electrical signal converted by the photodetector establishing the connection with the amplifier.
11. The method of claim 10 , wherein the amplifier comprises a plurality of input branches arranged in parallel, each of the plurality of input branches being coupled to one of the plurality of photodetectors.
12. The method of claim 11 , further comprising:
controlling, by a switch of the multiplexing circuit, the connection between one of the plurality of photodetectors and the amplifier, wherein the switch is arranged in one of the plurality of input branches of the amplifier.
13. The method of claim 11 , wherein the plurality of input branches are connected to a low-impedance node of the amplifier.
14. The method of claim 10 , comprising:
feeding back, by a feedback network, the output signal to an output terminal of the photodetector establishing the connection with the amplifier.
15. The method of claim 10 , comprising:
grounding the output terminal of the photodetector when the multiplexing circuit does not establish the connection between the photodetector and the amplifier.
16. A multi-channel operational amplifier circuit, comprising:
a plurality of input channels configured to receive input signals generated by a plurality of photodetectors;
an amplification unit coupled to the plurality of photodetectors through the plurality of input channels, wherein the amplification unit is shared by the plurality of input channels and configured to generate an output signal by amplifying an individual input signal received by a corresponding input channel; and
a multiplexing circuit configured to select one of the plurality of input channels for the amplification unit to amplify the input signal received by that input channel.
17. The multi-channel operational amplifier circuit of claim 16 , wherein the amplification unit comprises a plurality of input branches arranged in parallel, each of the plurality of input branches being coupled to one of the plurality of input channels.
18. The multi-channel operational amplifier circuit of claim 16 , wherein the multiplexing circuit comprises a plurality of switches, at least one of the plurality of switches being configured to control the selection of the one of the plurality of input channels.
19. The multi-channel operational amplifier circuit of claim 18 , wherein the at least one of the plurality of switches is connected in series with an input transistor configured to couple one of the plurality of photodetectors to the amplification unit.
20. The multi-channel operational amplifier circuit of claim 17 , wherein the plurality of input branches are connected to a low-impedance node of the amplification unit.