Varicap diode quality measurement - has coaxial line excited via antenna connected to HF source for application of overvoltage

摘要

The varicap diode is measured to select suitable components and to reject components which will ultimately be unsatisfactory. This is performed by the application of an over voltage when excited at a very high freouency. The varicap diode (1) is connected to terminals (A,B) on a coaxial line comprising a cylinder (10) and inner conductor (11). The remote end of the line is closed by an adjustable capacitor (12) and is coupled to a variable d.c. voltage (13) via a protective inductor (14). The line is excited via an antenna (15) connected to a high frequency source (16). A receiving antenna (17) detects the field inside the line and applies the value to a memory circuit (19) via an amplifier. A circuit (20) compares the value with a reference to select the diode for a particular category.