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Adaptive array sensor and electrical circuit therefore

Imported: 23 Feb '17 | Published: 22 Oct '02

Stéphane Bourquin, Peter Seitz

USPTO - Utility Patents

Abstract

The on-chip electrical circuit (

1) for the detection of modulated signals (I), e.g., light, comprises sensor means (PS), e.g., a photosensor, and feedback means (FB) including a low-pass frequency filter. The circuit (

1) further comprises a voltage-controlled current source (CS), the input of which is connected to the output of the feedback means (FB) and the output of which is connected in series with the photosensor (PS) in a common node. The common node is connected to the input of an amplifier (AMP). The output of the amplifier (AMP) may be connected to a rectifier (RF), followed by a low-pass filter (LPF). A plurality of such electrical detection circuits (

1) with parallel outputs can form a one-dimensional or two-dimensional array sensor for the coherent or heterodyne analog detection of intensity modulated optical signals simultaneously for all pixels with a high dynamic range. The array sensor may be used, e.g., in single or multiple wavelength interferometry, and especially in optical low-coherence tomography.

Description

DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail hereinafter relative to the attached schematic drawings.

FIG. 1 shows (a) a typical light intensity modulated signal reaching a pixel of a sensor, and (b) the desired electrical signal at the sensor output.

FIG. 2 shows a block diagram of a sensor circuit according to the invention.

FIG. 3 shows the intensity of an optical signal vs. time.

FIG. 4 shows the electrical signal at the output of an amplifier in the circuit of FIG. 2 vs. time.

FIG. 5 shows the electrical signal at the output of a rectifier in the circuit of FIG. 2 vs. time.

FIG. 6 shows the electrical signal at the output of the circuit of FIG. 2 vs. time.

FIG. 7 shows a one-dimensional arrangement of circuits according to the invention.

FIG. 8 shows a two-dimensional arrangement of circuits according to the invention.

FIG. 9 shows details of an embodiment of the sensor circuit according to the invention.

Claims

1. An electrical circuit for the adaptive detection of a modulated signal within a selected modulation frequency range, comprising:

2. The electrical circuit according to claim 1, wherein the sensor means comprises a photodiode.

3. The electrical circuit according to claim 1, wherein the amplifier means comprises a CMOS inverter amplifier.

4. The electrical circuit according to claim 1, wherein the low-pass filter comprises a capacitor and a PMOS transistor.

5. The electrical circuit according to claim 1, wherein the current source is a PMOS transistor connected between a fixed voltage and the sensor means.

6. The electrical circuit according to claim 1, further comprising rectifier means connected to the output of the amplifier.

7. The electrical circuit according to claim 6, wherein the rectifier means comprises a differential amplifier with a diode connected in the negative feedback, the anode of the diode being connected to the negative input node of the differential amplifier, a PMOS transistor being connected between the negative input of the differential amplifier and a fixed voltage, and the output node of the rectifier being the negative input node of the differential amplifier.

8. The electrical circuit according to claim 6, further comprising a low-pass filter connected to the output of the rectifier.

9. The electrical circuit according to claim 8, wherein the low-pass filter is a PMOS follower with the input connected to the output of the rectifier, a capacitor being connected between the output of the PMOS follower and a fixed voltage.

10. A one-dimensional or two-dimensional adaptive array sensor comprising a plurality of electrical circuits according to claim 1 with parallel outputs.

11. The one-dimensional or two-dimensional array sensor according to claim 10, comprising at least one on-chip address decoder for individually reading out each electrical circuit of a group of electrical circuits.

12. A method for adaptively detecting a modulated signal comprising the steps of;

13. The method according to claim 12, further comprising the steps of rectifying a part of the amplified electrical signal, and frequency filtering the rectified electrical signal.

14. The electrical circuit according to claim 1, wherein said integrator comprises a differential amplifier with a capacitor in the negative feedback and a PMOS transistor connected between the output of the low-pass filter and the negative input of the differential amplifier.