Low power stabilized voltage divider network
A voltage divider network in combination with a voltage multiplier circuit voltage biases the electrodes of a photomultiplier tubes or related device. The circuit exploits the several voltage levels produced at successive stages of a voltage multiplier circuit in order to optimize the voltage divider network with respect to power consumption, current draw from the power supply, operating stability, and linear operation of the photomultiplier tube.
1. A photomultiplier tube comprising:
a photocathode;
first and second dynodes;
an anode; and
an electrode biasing circuit comprising
a voltage multiplier circuit adapted for connection to a source of electric power, said voltage multiplier circuit having first and second voltage taps for providing first and second tap voltages;
a first stage voltage divider network operatively connected to the first voltage tap of said voltage multiplier circuit; and
a second stage voltage divider network operatively connected to the second voltage tap of said voltage multiplier circuit;
said first stage voltage divider being operatively connected to said photocathode and to said first dynode for providing biasing voltages thereto, and said second stage voltage divider network being operatively connected to said second dynode and to said anode for providing biasing voltages thereto.
2. The photomultiplier tube of claim 1 wherein the first stage voltage divider network comprises an electrical resistor connected between said photocathode and said first dynode and the second stage voltage divider network comprises a second electrical resistor connected between said second dynode and said anode.
3. The photomultiplier tube claim 1 wherein the first dynode comprises a plurality of first dynodes and the second dynode comprises a plurality of second dynodes and said first stage voltage divider network is operative connected to each of said plurality of first dynodes for providing biasing voltages thereto and said second voltage divider network is operatively connected to each of said plurality of second dynodes for providing biasing voltages thereto.
4. The photomultiplier tube of claim 3 wherein the first stage voltage divider network comprises a first plurality of electrical resistors each connected between adjacent first dynodes and the second stage voltage divider network comprises a second plurality of electrical resistors each connected between adjacent second dynodes.
5. The photomultiplier tube of claim 1 wherein the first stage voltage divider network comprises an electrical resistor connected between said photocathode and said first dynode and the second stage voltage divider network comprises a transistor connected in an emitter-follower configuration between said second dynode and said anode.
6. The photomultiplier tube of claim 3 wherein the first stage voltage divider network comprises a plurality of electrical resistors each connected between adjacent first dynodes and the second stage voltage divider network comprises a plurality of transistors each connected in an emitter-follower configuration between adjacent second dynodes.
7. The photomultiplier of claim 6 wherein the second stage voltage divider network comprises a current source operatively connected to said plurality of transistors.
8. The photomultiplier tube of claim 7 wherein said current source comprises a bipolar transistor that provides a substantially constant collector current to said plurality of transistors when in operation.
9. The photomultiplier tube of claim 7 wherein said current source comprises a field-effect transistor that provides a substantially constant collector current to said plurality of transistors when in operation.
10. The photomultiplier tube of claim 7 wherein the current source comprises a transistor, a Zener diode, and one or more resistors which are connected such that in operation, the transistor is biased to provide a substantially constant collector current to said plurality of transistors.