Apparatus for input amplifier stage

Claim 2

An amplifier having an output, comprising in combination: a high gain, low noise differential input stage including inverting input transistor means and non-inverting second transistor means, the base of the second transistor means to be controlled by a predetermined voltage wherein the emitter cross-sectional area of the second transistor is significantly greater than the emitter cross-sectional area of the input transistor; means for biasing the input transistor means and the second transistor means to substantially equal base to emitter voltages, thereby dividing the quiescent emitter current between the input transistor means and the second transistor means in substantially the same ratio as the emitter cross-sectional areas; and means for providing feedback from the output to the base of the input transistor means.

Claim 3

An amplifier according to claim 1 wherein the emitter cross-sectional area of the second transistor is approximately ten times greater than the emitter cross-sectional area of the input transistor.

Claim 4

An amplifier according to claim 1 further comprising a signal source connected to the base of the input transistor means.

Claim 5

An amplifier according to claim 3 wherein the signal source is a photo detector.

Claim 6

An amplifier according to claim 1 to be used with means for generating a reference voltage, wherein the means for providing feedback comprises in combination: first impedance means connecting the output to the base of the input transistor; and second impedance means connecting the reference voltage to the common connection of the first impedance means and the input transistor means.

Claim 7

An amplifier according to claim 1 to be used with means for generating a reference voltage, wherein the means for providing feedback comprises in combination: a capacitor, wherein the voltage across the capacitor is responsive to the voltage output of the amplifier averaged over a period of time; a first current divider branch connected to the base of the input transistor means and having a predetermined quiescent current; resistance means connecting the reference voltage to the common connection of the first current branch and the input transistor means for providing current to the first current divider branch; and a second current divider branch connected to the first current divider branch at the end opposite the resistance means and the input transistor means, wherein the current in the second current divider branch is controlled by the voltage across the capacitor, the quiescent current in the second branch being significantly greater than the quiescent current in the first branch, whereby the combination of the capacitor, the first current divider branch and the second current divider branch act as an automatic gain control circuit connected in a feedback relationship to the amplifier.

Claim 8

An amplifier according to claim 6 further comprising a signal source connected to the base of the input transistor means.

Claim 9

An amplifier according to claim 7 wherein the signal source is a photo detector.

Claim 10

An amplifier having an output, comprising in combination: a high gain, low noise differential input stage including inverting input transistor means and non-inverting second transistor means to be controlled by a predetermined voltage; means for biasing the input transistor means and the second transistor means wherein the quiescent current is substantially different in the second transistor means from the quiescent current in the input transistor means; and means for providing feedback from the output to the base of the input transistor means.

Claim 11

An amplifier having an output, comprising in combination: a high gain, low noise differential input stage including inverting input transistor means and non-inverting second transistor means to be controlled by a predetermined voltage; means for biasing the input transistor means and the second transistor means wherein the quiescent current is substantially different in the second transistor means from the quiescent current in the input transistor means; and means for providing feedback from the output to the base of the input transistor means.

Claim 12

An amplifier according to claim 9 further comprising a signal source connected to the base of the input transistor means.

Claim 13

An amplifier according to claim 10 wherein the signal source is a photo detector.

Claim 14

An amplifier according to claim 9 to be used with means for generating a reference voltage, wherein the means for providing feedback comprises in combination: first impedance means connecting the output to the base of the input transistor; and second impedance means connecting the reference voltage to the common connection of the first impedance means and the input transistor means.

Claim 15

An amplifier having an output, to be used with means for generating a reference voltage, comprising in combination: a high gain, low noise differential input stage including inverting input transistor means and non-inverting second transistor means to be controlled by a predetermined voltage; means for biasing the input transistor means and the second transistor means wherein the quiescent current is substantially different in the second transistor means from the quiescent current in the input transistor means; a capacitor, wherein the voltage across the capacitor is responsive to the voltage output of the amplifier averaged over a period of time; a first current divider branch connected to the base of the input transistor means and having a predetermined quiescent current; resistance means connecting the reference voltage to the common connection of the first current branch and the input transistor means for providing current to the first current divider branch; and a second current divider branch connected to the first current divider branch at the end opposite the resistance means and the input transistor means, wherein the current in the second current divider branch is controlled by the voltage across the capacitor, the quiescent current in the second branch being significantly greater than the quiescent current in first branch, whereby the combination of the capacitor, the first current divider branch and the second current divider branch act as an automatic gain control circuit connected in a feedback relationship to the amplifier.

Claim 16

An amplifier having an output, to be used with means for generating a reference voltage, comprising in combination: a high gain, low noise differential input stage including inverting input transistor means and non-inverting second transistor means to be controlled by a predetermined voltage; means for biasing the input transistor means and the second transistor means wherein the quiescent current is substantially different in the second transistor means from the quiescent current in the input transistor means; a capacitor, wherein the voltage across the capacitor is responsive to the voltage output of the amplifier averaged over a period of time; a first current divider branch connected to the base of the input transistor means and having a predetermined quiescent current; resistance means connecting the reference voltage to the common connection of the first current branch and the input transistor means for providing current to the first current divider branch; and a second current divider branch connected to the first current divider branch at the end opposite the resistance means and the input transistor means, wherein the current in the second current divider branch is controlled by the voltage across the capacitor, the quiescent current in the second branch being significantly greater than the quiescent current in first branch, whereby the combination of the capacitor, the first current divider branch and the second current divider branch act as an automatic gain control circuit connected in a feedback relationship to the amplifier.

Claim 17

An amplifier according to claim 13 further comprising a signal source connected to the base of the input transistor means.

Claim 18

An amplifier according to claim 14 wherein the signal source is a photo detector.