Solid state RF oscillator-detector for flow cytometer
First Claim
1. A circuit for use in an apparatus for conducting electrical measurements of particles contained in a carrier fluid, that passes through an aperture in a measurement cell to which an electric field is applied, said circuit comprising a solid state RF Hartley oscillator-detector containing a plurality of solid state devices having respectively different transfer function characteristics, and an RF resonant circuit electrically coupled to said plurality of solid state devices and said measurement cell.
0 Assignments
0 Petitions
Accused Products
Abstract
A junction field effect transistor (JFET) RF oscillator-detector circuit generates an RF signal for an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a cytometer flow cell. The JFET oscillator includes a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, that are biased to operate at square law detection regions of their respective VDS vs. IDS characteristics. One JFET operates in Class C mode, while the other operates in Class AB mode. An RF resonant circuit is electrically coupled to the JFETs and to the measurement cell, and is operative to establish the frequency of an RF field applied to the measurement cell. An RF load change detection circuit is coupled to the RF resonator circuit and is operative to detect an RF load change associated with a modification of the RF field as a result of a particle within the measurement cell aperture.
-
Citations
23 Claims
- 1. A circuit for use in an apparatus for conducting electrical measurements of particles contained in a carrier fluid, that passes through an aperture in a measurement cell to which an electric field is applied, said circuit comprising a solid state RF Hartley oscillator-detector containing a plurality of solid state devices having respectively different transfer function characteristics, and an RF resonant circuit electrically coupled to said plurality of solid state devices and said measurement cell.
-
13. A junction field effect transistor (JFET) RF oscillator-detector circuit for use in an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a measurement cell to which an electric field is applied, said JFET RF oscillator comprising:
-
a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, and being biased to operate at square law detection regions of their respective VDS vs. IDS characteristics, a first JFET of said plurality of JFETs operating in a first class mode, and a second JFET of said plurality of JFETs operating in second class mode different from said first class mode;
an RF resonant circuit electrically coupled to said plurality of parallel-coupled JFETs and to said measurement cell, and establishing the frequency of an RF field applied to said measurement cell; and
an RF load change detection circuit coupled to said RF resonator circuit and being operative to detect an RF load change associated with a modification of said RF field as a result of a particle within said measurement cell aperture.
-
-
21. For use in an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a measurement cell to which an electric field is applied, a method of coupling an RF field to said measurement cell and deriving changes in said RF electric field associated with the presence of a particle within said measurement cell aperture, said method comprising the steps of:
-
(a) providing an RF oscillator that includes a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, and biased to operate at square law detection regions of their respective VDS vs. IDS characteristics, with a first JFET of said plurality of JFETs operating in a first class mode, and a second JFET of said plurality of JFETs operating in second class mode different from said first class mode, and an RF resonant circuit electrically coupled between said plurality of parallel-coupled JFETs and to said measurement cell, and being operative to establish the frequency of an RF field applied to said measurement cell; and
(b) coupling said RF resonator circuit to an RF load detection circuit that is operative to detect an RF load change associated with a modification of said RF field as a result of said presence of a particle within said measurement cell aperture. - View Dependent Claims (22, 23)
-
Specification