Non-linear transimpedance amplifier

Claim 2

A transimpedance amplifier having a broad dynamic range for amplifying an input signal over an extended range of levels and for providing an output signal representative of the input signal, the amplifier utilizing an externally generated reference voltage and an externally generated time varying signal, the amplifier comprising: (a) an accumulator for receiving the input signal, for accumulating a charge, and for generating an accumulator output signal representative of the charge accumulated; (b) a saturation sensing circuit in electrical communication with said accumulator for sensing accumulator saturation and for generating a saturation sensing circuit output signal representative of the time at which said accumulator becomes saturated; and (c) a compensation circuit in electrical communication with said accumulator and said saturation sensing circuit for supplementing the accumulator output signal in response to the saturation sensing circuit output signal and for generating a compensation circuit output signal; (d) wherein the compensation circuit output signal is representative of the input signal whether or not the input signal causes saturation of the accumulator.

Claim 3

The transimpedance amplifier as recited in claim wherein said accumulator comprises a reset integrator.

Claim 4

The transimpedance amplifier as recited in claim wherein said saturation sensing circuit comprises: (a) a comparator in electrical communication with said accumulator for comparing the accumulator output to the reference voltage and for generating a comparator output when the accumulator output is at a predetermined potential relative to the reference voltage; and (b) a sample and hold circuit in electrical communication with said comparator for receiving the external time varying signal and for generating a sample and hold circuit output signal representative of the amplitude of the time varying signal when the comparator output is generated.

Claim 5

The transimpedance amplifier as recited in claim wherein said compensation circuit receives a signal representative of the accumulator output signal and a signal representative of the sample and hold circuit output signal, and generates a compensation circuit output signal representative of the sum thereof.

Claim 6

The transimpedance amplifier as recited in claim wherein the reference voltage is representative of the accumulator output signal at accumulator saturation.

Claim 7

The transimpedance amplifier as recited in claim wherein the time varying signal is characterized by a decreasing amplitude.

Claim 8

The transimpedance amplifier as recited in claim wherein the time varying signal comprises a periodic linearly decreasing ramp signal.

Claim 9

The transimpedance amplifier as recited in claim wherein said accumulator comprises a capacitor for accumulating a charge representative of the input signal.

Claim 10

The transimpedance amplifier as recited in claim wherein said accumulator further comprises a switch for periodically discharging any charge accumulated upon said capacitor.

Claim 11

The transimpedance amplifier as recited in claim 9 wherein said compensation circuit output signal is a non-linear function of the input signal.

Claim 12

A transimpedance amplifier having a broad dynamic range for amplifying an input signal over an extended range of levels utilizing an externally generated reference voltage and an externally generated time varying signal, the amplifier comprising: (a) an accumulator for accumulating a charge representative of the input signal, and for generating an accumulator output signal representative of the accumulated charge; (b) a comparator in electrical communication with said accumulator for comparing the accumulator output to the reference voltage and for generating an output when the accumulator output is at a predetermined potential relative to the reference voltage; (c) a sample and hold circuit in electrical communication with said comparator for receiving the time varying signal and for generating a sample and hold output signal representative of the amplitude of the time varying signal when the comparator output is generated; (d) a summing circuit in electrical communication with said accumulator and said sample and hold circuit for receiving a signal representative of the accumulator output signal and a signal representative of the sample and hold output signal and for generating a summing circuit output signal representative of the sum thereof; (e) wherein the summing circuit output signal is representative of the input signal whether or not the input signal causes saturation of said accumulator.

Claim 13

A transimpedance amplifier having a broad dynamic range for amplifying an input signal over an extended range of levels utilizing an externally generated reference voltage and an externally generated time varying signal, the amplifier comprising: (a) an accumulator for accumulating a charge representative of the input signal, and for generating an accumulator output signal representative of the accumulated charge; (b) a comparator in electrical communication with said accumulator for comparing the accumulator output to the reference voltage and for generating an output when the accumulator output is at a predetermined potential relative to the reference voltage; (c) a sample and hold circuit in electrical communication with said comparator for receiving the time varying signal and for generating a sample and hold output signal representative of the amplitude of the time varying signal when the comparator output is generated; (d) a summing circuit in electrical communication with said accumulator and said sample and hold circuit for receiving a signal representative of the accumulator output signal and a signal representative of the sample and hold output signal and for generating a summing circuit output signal representative of the sum thereof; (e) wherein the summing circuit output signal is representative of the input signal whether or not the input signal causes saturation of said accumulator.

Claim 14

The transimpedance amplifier as recited in claim wherein the reference voltage is representative of the accumulator output signal at accumulator saturation.

Claim 15

The transimpedance amplifier as recited in claim 12 wherein the time varying signal is characterized by a decreasing amplitude.

Claim 16

The transimpedance amplifier as recited in claim 12 wherein the time varying signal comprises a periodic linearly decreasing ramp signal.

Claim 17

The transimpedance amplifier as recited in claim 12 wherein said accumulator comprises a capacitor for accumulating a charge representative of the input signal.

Claim 18

The transimpedance amplifier as recited in claim 15 wherein said accumulator further comprises a switch for periodically discharging any charge accumulated upon said capacitor.

Claim 19

The transimpedance amplifier as recited in claim 16 wherein the summing circuit output signal is a non-linear representation of the input signal.

Claim 22

The method as recited in claim 18 wherein the step of accumulating a charge representative of the input signal within an accumulator comprises accumulating a charge representative of the input signal within a reset integrator.

Claim 23

The method as recited in claim 19 wherein the step of sensing the time at which the accumulator becomes saturated comprises the step of comparing the accumulator output signal to a reference voltage.

Claim 24

The method as described in claim 20 wherein the step of supplementing the accumulator output signal comprises the steps of: (a) receiving a time varying signal and generating an offset signal representative of the amplitude of the time varying signal at a predetermined time relative to the time at which the accumulator becomes saturated; and (b) summing the accumulator output signal with said offset signal.

Claim 25

The method as described in claim 21 wherein the step of receiving a time varying signal comprises the step of receiving a signal having a decreasing amplitude.

Claim 26

The method as described in claim 21 wherein the step of receiving a time varying signal comprises the step of receiving a periodic linearly decreasing ramp signal.