Constant current source

Claim 2

In combination: high input impedance voltage follower means having an input terminal connected to a load and having an output terminal isolated from said input terminal, said voltage follower meanS comprising a field effect transistor having a source, drain, and gate electrodes, said gate electrode connected to said input terminal and said source electrode connected to said output terminal; impedance means connected to said input terminal; a voltage source, said voltage source comprising a voltage regulator having a first terminal thereof connected to said voltage follower output terminal and having a second terminal thereof connected to a point common with said impedance means and said drain electrode of said field effect transistor in order to supply thereto a voltage signal regulated with respect to the voltage at said output terminal; and means connecting said voltage source between said output terminal and said impedance means, whereby a substantially constant voltage is developed across said impedance means for establishing a substantially constant current therethrough to said load.

Claim 3

The combination of claim 1 including: current regulating transistor means connected to said source electrode of said field effect transistor, said output terminal being located at a common point between said source electrode and said transistor means.

Claim 4

The combination of claim 1 wherein said load includes capacitance means connected to said input terminal and adapted to be charged by current supplied through said impedance means, the voltage across said capacitance means being translated to said output terminal to provide an output ramp voltage signal thereat.

Claim 5

In combination, impedance means, voltage regulator means, voltage follower means exhibiting high imput impedance and low output impedance and having at least an input terminal and an output terminal, said voltage follower means comprising a field effect transistor having source, drain, and gate electrodes, said gate electrode connected to the input terminal of said voltage follower means, said source electrode connected to the output terminal of said voltage follower means, and said drain electrode connected to a common junction with a first terminal of said impedance means and said voltage regulator means in order to receive a voltage signal therefrom, load means having a first terminal thereof connected to a common junction with a second terminal of said impedance means and said input terminal of said voltage follower means, said voltage regulator means connected from said output terminal of said voltage follower means to said first terminal of said impedance means, and constant current source means connected from said output terminal of said voltage follower means to a second terminal of said load means.

Claim 6

In combination, impedance means, voltage regulator means, voltage follower means exhibiting high imput impedance and low output impedance and having at least an input terminal and an output terminal, said voltage follower means comprising a field effect transistor having source, drain, and gate electrodes, said gate electrode connected to the input terminal of said voltage follower means, said source electrode connected to the output terminal of said voltage follower means, and said drain electrode connected to a common junction with a first terminal of said impedance means and said voltage regulator means in order to receive a voltage signal therefrom, load means having a first terminal thereof connected to a common junction with a second terminal of said impedance means and said input terminal of said voltage follower means, said voltage regulator means connected from said output terminal of said voltage follower means to said first terminal of said impedance means, and constant current source means connected from said output terminal of said voltage follower means to a second terminal of said load means.

Claim 7

The combination of claim 4, wherein said voltage regulator means comprises a diode means and a transistor means having collector, base and emitter electrodes, a first terminal of said diode means connected to said output terminal of said voltage follower means and a second terminal of said diode means connected at a common junction with the base electrode of said transistor means, the emitter electrode of said transistor means connected at a common junction with the first terminal of said impedance means and the drain electrode of said field effect transistor.

Claim 8

The combination of claim 4, wherein said load means is a capacitive means, said capacitive load means electrically connected in series with said impedance means, said voltage follower means connected to said capacitive load means at said common junction to detect a voltage across said load means and to produce an output signal representative of said voltage, and said voltage regulator means connected to receive said output signal from said voltage follower means and to supply a corresponding voltage signal to said impedance means at said first terminal thereof.