Voltage controlled oscillator

DETAILED DESCRIPTION I claim: 1.
A wide range voltage controlled oscillator comprising: a timing capacitor; means for selectively charging said capacitor; a voltage controlled current source for discharging said capacitor at a rate which is a function of an externally supplied control voltage; current bias circuitry including at least two transistors whose bases are connected together and whose emitters are provided with respective current value determining resistors, said bias circuitry including also means for applying a preselected current to the collector of a first one of said two transistors thereby to establish a corresponding current at the collector of a second one of said transistors; a differential, emitter-follower input circuit for controlling said charging means, said input circuit including at least two transistors which are similar in type to said bias circuitry transistors, the emitters of said input circuit transistors being connected in common to the collector of said second one of said current bias transistors, the base of one of said input circuit transistors being connected to a reference voltage source and the base of the other of said input transistors being connected to said capacitor; a buffer transistor similar in type to said bias circuitry transistors, the base of said buffer transistor being connected to the collector of said first bias circuit transistor and the emitter of said buffer transistor being connected to the base terminals of said first and second bias circuit transistors for applying bias current thereto whereby the collector current in said buffer transistor is proportional to the collector currents in said first and second input circuit transistors and inversely proportional to their gains; and current mirror means having an input connected to the collector of said buffer transistor and an output connected to the base of said second input circuit transistor thereby to provide to said second input transistor a compensated bias current which prevents said capacitor from being discharged by the base current drawn by said second input transistor, whereby the discharging of said capacitor is controlled essentially solely by said voltage controlled current source