Solid-state optical receiver driver system and method for testing a solid-state optical receiver driver system

Abstract

Embodiments of the invention relates to a Solid-state optical receiver driver system, particularly for automotive applications, comprising at least one optical receiver channel, the optical receiver channel being connectable to a respective optical receiver, which is characterized in that the solid-state optical receiver driver system further comprises at least one test signal generation unit, for providing a test signal to the at least one optical receiver channel. The invention further relates to a method for testing a solid-state optical receiver driver system.

Claims

1. A solid-state optical receiver driver system, comprising: at least one optical receiver channel, the optical receiver channel being connectable to a respective optical receiver; and at least one test signal generator unit that provides a test signal to the at least one optical receiver channel, wherein the optical receiver channel comprises a transimpedance amplifier and an analog-to-digital converter, and wherein the gain of the test signal generation unit matches the gain of the transimpedance amplifier of the optical receiver channel.

2. The solid-state optical receiver driver system according to claim 1, wherein each optical receiver channel comprises a separate test signal generation unit.

3. The solid-state optical receiver driver system according to claim 1, wherein the optical receiver channel comprises a multiplexer at the input, multiplexing between the signal of the corresponding optical receiver and the signal of the at least one test signal generation unit.

4. The solid-state optical receiver driver system according to claim 1, wherein the transimpedance amplifier of the optical receiver channel comprises a feedback resistor and wherein the test signal generation unit comprises a replica of this feedback resistor for gain matching the amplifier and the test signal generation unit.

5. The solid-state optical receiver driver system according to claim 1, wherein the test signal generation unit further comprises an output for providing the test signal of the test signal generation unit to an external unit.

6. A solid-state optical receiver driver system, comprising: at least one optical receiver channel, the optical receiver channel being connectable to a respective optical receiver; and at least one test signal generator unit that provides a test signal to the at least one optical receiver channel, wherein the test signal generation unit comprises a current based digital-to-analog converter and a current generation unit.

7. A method for testing a solid-state optical receiver driver system, comprising: generating a test signal within the solid-state optical receiver driver system; applying the generated test signal to at least one optical receiver channel of the solid-state optical receiver driver system; monitoring the output of the at least one optical receiver channel in response to the applied test signal; and comparing the output of the at least one optical receiver channel to an expected output of the at least one optical receiver channel, wherein the at least one optical receiver channel amplifies the input signal and converts the analog input signal to a digital output signal, and further comprising matching the gain of a test signal generation unit to the gain of an amplifier of the at least one optical receiver channel.

8. The method for testing a solid-state optical receiver driver system according to claim 7, wherein a separate test signal is generated for each optical receiver channel of the solid-state optical receiver driver system.

9. The method for testing a solid-state optical receiver driver system according to claim 7, wherein the steps of generating, applying, monitoring and comparing are executed for each optical receiver channel of the solid-state optical receiver driver system in parallel.

10. The method for testing a solid-state optical receiver driver system according to claim 7, further comprising multiplexing between the test signal and a signal of an optical receiver.

11. The method for testing a solid-state optical receiver driver system according claim 7, further comprising providing the test signal to an external unit.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 a block diagram of an optical receiver system according to the prior art,

(2) FIG. 2 a block diagram of an optical receiver system comprising a solid-state optical receiver driver system according to a first embodiment of the invention,

(3) FIG. 3 a block diagram of a solid-state optical receiver driver system according to a second embodiment of the invention for an optical receiver system,

(4) FIG. 4 a block diagram of a solid-state optical receiver driver system according to a third embodiment of the invention for an optical receiver system, and

(5) FIG. 5 a block diagram of a solid-state optical receiver driver system according to a fourth embodiment of the invention for an optical receiver system.

DETAILED DESCRIPTION

(6) FIG. 1 shows a block diagram of an optical receiver system 10 according to the prior art. Such an optical receiver system 10 is for example used in light detection and ranging (Lidar) systems, also called laser detection and ranging (Ladar) systems.

(7) Light detection and ranging systems measure the distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with the optical receiver system 10. Differences in laser return times and wavelength can then be used to make 3-D representations of the target. Recently such light detection and ranging systems have been used in autonomous vehicles, for detecting any obstacles in the surroundings of the vehicle. In such applications the accuracy and availability of the light detection and ranging system is essential.

(8) Alight detection and ranging system usually comprises at least one light source for emitting light to the surroundings of the light detection and ranging system and an optical receiver system 10 for detecting any light signal reflected and/or backscattered from a target in the surroundings of the light detection and ranging system.

(9) FIG. 1 shows a block diagram of an optical receiver system 10 according to the prior art for a light detection and ranging system. The optical receiver system 10 comprises a string 2 of optical receivers 3. This string 2 of optical receivers 3 is usually arranged in the front part of a vehicle. The optical receivers 3 receive the light signal reflected and/or backscattered from the target in the surroundings of the light detection and ranging system and convert these light signals into analog electrical signals.

(10) The optical receiver system 10 further comprises a solid-state optical receiver driver system 1 for receiving and processing the analog electrical signals of the string 2 of optical receivers 3. Advantageously the solid-state optical receiver driver system 1 is not located at the front part of the vehicle, but at a more remote location, due to the environmental stresses occurring in the front part of the vehicle. Therefore, the string 2 of optical receivers 3 is connected to the solid-state optical receiver driver system 1 by a cable 15.

(11) The solid-state optical receiver driver system 1 comprises a separate optical receiver channel 4 for each optical receiver 3 of the string of optical receivers 3. The separate optical receiver channels 4 are indicated by a dashed line in FIG. 1. Each optical receiver channel 4 is connected to one optical receiver 3 of the string 2 of optical receivers 3 by cable 15.

(12) Each optical receiver channel 4 for example comprises a transimpedance amplifier 7 for converting and amplifying the analog electrical signal of the optical receiver 3 and an analog-to-digital converter 8 for converting the amplified analog electrical signal of the optical receiver 3 to a digital signal.

(13) The digital signal can be further processed by an internal control unit (not shown) of the solid-state optical receiver driver system 1 or transmitted to an external control unit (not shown). Differences in the received laser return times and wavelength are used to calculate a 3-D representation of a target in the surroundings of the light detection and ranging system.

(14) FIG. 2 shows a block diagram of an optical receiver system 10 comprising a solid-state optical receiver driver system 1 according to a first embodiment of the invention. The optical receiver 10 shown in FIG. 2 differs from the optical receiver system 10 shown in FIG. 1 in that the solid-state optical receiver driver system 1 further comprises a test signal generation unit 5, for providing a test signal to the optical receiver channels 4. The test signal can be for example a rectangular or triangular pulse or a DC current.

(15) The test signal generation unit 5 generates a test signal within the solid-state optical receiver driver system 1. This test signal is applied to the optical receiver channels 4 of the solid-state optical receiver driver system 1. The test signal can be either applied to all optical receiver channels 4 at the same time or subsequently one after the other. The output of the optical receiver channels 4 in response to the applied test signal is monitored and compared to an expected output of the optical receiver channel 4 based on the applied test signal. This comparison can be performed by an internal or external control unit.

(16) In FIG. 3 a second embodiment of a solid-state optical receiver driver system 1 according to the invention is shown. The second embodiment shown in FIG. 3 differs from the first embodiment shown in FIG. 2 in that the solid-state optical receiver driver system 1 comprises a separate test signal generation unit 5 for each optical receiver channel 4. Thus, the optical receiver channels 4 are completely decoupled from one another, thereby reducing interferences and increasing the accuracy of the solid-state optical receiver driver system 1.

(17) Using a separate test signal generation unit 5 for each optical receiver channel 4 a test signal can be applied to each optical receiver channel 4 at the same time, without creating any interferences.

(18) FIG. 4 shows a third embodiment of a solid-state optical receiver driver system 1. In FIG. 4 only one optical receiver channel 4 with a corresponding test signal generation unit 5 is shown, but the solid-state optical receiver driver system 1 can comprise more optical receiver channels 4 and associated test signal generation units 5, as for example shown in FIG. 3.

(19) The optical receiver channel 4 of the solid-state optical receiver driver system 1 shown in FIG. 4 comprises a multiplexer 6 at the input, multiplexing between the signal of the corresponding optical receiver 3 ant the test signal of the test signal generation unit 5. The multiplexer decouples the test signal from the signal of the optical receiver 3, thereby reducing interferences between these signals and increasing the accuracy of the solid-state optical receiver driver system 1.

(20) Furthermore, according to the third embodiment of FIG. 4 the transimpedance amplifier 7 of the optical receiver channel 4 comprises a feedback resistor 9.

(21) The third embodiment of FIG. 4 of the solid-state optical receiver driver system 1 further shows more details with respect to the test signal generation unit 5. The test signal generation unit 5 comprises for example a digital-to-analog converter 12 and a current generator 13.

(22) Advantageously the gain of the test signal generation unit 5 matches the gain of the transimpedance amplifier 7 of the optical receiver channel 4. This is for example achieved by a resistor 11 of the current generation unit 13, which is a replica of the feedback resistor 9 of the amplifier 7 of the optical receiver channel 4.

(23) The current generation unit 13 provides a current with a defined amplitude, preferably for gain matching the amplifier 7 of the optical receiver channel 4. This current is provided to the digital-to-analog converter 12, which can simply forward this generated current to the multiplexer 6 of the optical receiver channel 4 as it is or scale it according the digital input code. Alternatively, the digital-to-analog converter can pulse the current of the current generation unit 13 to provide a rectangular pulse to the multiplexer 6 of the optical receiver channel 4 or the digital-to-analog converter can integrate the current provided by the current generation unit 13 over a capacitor to provide a triangular pulse to the multiplexer 6 of the optical receiver channel 4. Thus, preferably the digital-to-analog converter 12 is current based.

(24) In FIG. 5 a fourth embodiment of a solid-state optical receiver driver system 1 according to the invention is shown. The details of the current generation unit 13 of the test signal generation unit 5 have been masked by a black-box in comparison to the third embodiment of the invention shown in FIG. 4.

(25) Mainly the fourth embodiment shown in FIG. 5 differs from the third embodiment shown in FIG. 4 in that the test signal generation unit 5 further comprises an output 14 for the generated test signal. The output 14 can provide the generated test signal to an external unit, for example to compare the test signal with the results of the processing of the test signal by the optical receiver channel 4. 1 solid-state optical receiver driver system 1 2 string of optical receivers 3 optical receiver 4 optical receiver channel 5 test signal generation unit 6 multiplexer 7 amplifier 8 analog-to-digital converter 9 feedback resistor 10 optical receiver system 11 replica of feedback resistor 12 digital-to-analog converter 13 current generation unit 14 test signal output 15 cable