Phased locked loop with voltage controlled oscillator

Claim 2

In a phase locked loop, a phase comparator for receiving the input signal and providing an output, filtering means coupled to the output of the phase comparator and providing a filtered output serving as a frequency control signal and a voltage controlled oscillator coupled between the output of the filtering means and the phase comparator, said voltage controlled oscillator comprising multivibrator means including first and second transistors, each having a base, collector and emitter, diode means connected to the collector of said first and second transistors for maintaining the voltage swings at the collectors of said first and second transistors equal and at the forward junction voltage of said diode means and means for varying the frequency of oscillation of said multivibrator means in response to said frequency control signal including variable current source means coupled to the emitters of said first and second transistors said current source means being responsive to said frequency control signal to vary the amount of current produced by said current source means to vary the output signal of the multivibrator means said phase comparator including at least two transistors, said comparator comparing the phase of the output signal of the multivibrator with the input signal for providing a difference signal indicative of the phase difference between such signals, said two transistors of said phase comparator also serving as said diode means of said multivibrator, said filtering means filtering said difference signal and providing said frequency control signal which is applied to said current source means, whereby the frequency of the output signal of said multivibrator is identical to the frequency of said input signal.

Claim 3

A phase locked loop as in claim 1 wherein said transistors of said multivibrator and said phase comparator are cascade connected together with a common biasing means for supplying biasing voltage to said transistors of said multivibrator and said phase comparator.

Claim 4

A phase locked loop as in claim 2 in which said transistors of said voltage controlled oscillator and said phase comparator are fed from a common current supply.

Claim 5

A phase locked loop as in claim 1 in which the transistor pairs of said multivibrator and said phase comparator form a balanced circuit for eliminating spurious signals.

Claim 6

A phase locked loop as in claim 1 in which said phase comparator includes two additional transistors for producing a doubly balanced circuit system, said additional two transistors being coupled to said first-named two transistors to form a bipolar analog multiplier to doubly balance said system cancelling out DC offset bias and any product of the input signal with said DC bias which exists in such circuit.

Claim 7

A phase locked loop as in claim 1 together with a semiconductive substrate in which the substantial majority of the components of the phase comparator and the voltage controlled oscillator are integrated.

Claim 8

In a phase locked loop, a phase comparator for receiving the input signal and providing an output, filtering means coupled to the output of the phase comparator and providing a filtered output serving as a frequency control signal and a voltage controlled oscillator coupled between the output of the filtering means and the phase comparator, said voltage controlled oscillator comprising multivibrator means including first and second transistors each having a base, Collector and emitter, diode means connected to the collector of said first and second transistors for maintaining the voltage swings at the collectors of said first and second transistors equal and at the forward junction voltage of said diode means and means for varying the frequency of oscillation of said multivibrator means in response to said frequency control signal including variable current source means coupled to the emitters of said first and second transistors, said current source means being responsive to said frequency control signal to vary the amount of current produced by said current source means to vary the output signal of the multivibrator whereby said output signal has a frequency variation which is linearly proportional to said variation of said current source means said current source means including a common constant current source coupled to a current divider network having three legs, two of the legs being coupled to said emitters of said transistors of said multivibrator and a third leg carrying the remainder of the current of said common constant current source, and said current source means also including means responsive to said frequency control signal coupled to said three legs of said current divider network for varying the current in said two legs coupled to said emitters of said multivibrator transistors in an opposite sense relative to said variation of current in said third leg in response to said variation in the magnitude of said frequency control signal whereby said common current source is maintained constant and said differential variation of currents of said legs stabilizes the temperature characteristics of said current source means.

Claim 9

In a phase locked loop, a phase comparator for receiving the input signal and providing an output, filtering means coupled to the output of the phase comparator and providing a filtered output serving as a frequency control signal and a voltage controlled oscillator coupled between the output of the filtering means and the phase comparator, said voltage controlled oscillator comprising multivibrator means including first and second transistors each having a base, Collector and emitter, diode means connected to the collector of said first and second transistors for maintaining the voltage swings at the collectors of said first and second transistors equal and at the forward junction voltage of said diode means and means for varying the frequency of oscillation of said multivibrator means in response to said frequency control signal including variable current source means coupled to the emitters of said first and second transistors, said current source means being responsive to said frequency control signal to vary the amount of current produced by said current source means to vary the output signal of the multivibrator whereby said output signal has a frequency variation which is linearly proportional to said variation of said current source means said current source means including a common constant current source coupled to a current divider network having three legs, two of the legs being coupled to said emitters of said transistors of said multivibrator and a third leg carrying the remainder of the current of said common constant current source, and said current source means also including means responsive to said frequency control signal coupled to said three legs of said current divider network for varying the current in said two legs coupled to said emitters of said multivibrator transistors in an opposite sense relative to said variation of current in said third leg in response to said variation in the magnitude of said frequency control signal whereby said common current source is maintained constant and said differential variation of currents of said legs stabilizes the temperature characteristics of said current source means.

Claim 10

A phase locked loop as in claim 7 wherein the means for varying said currents in said legs includes a transistor in each of said legs, said frequency control signal being applied between the base of the transistor of said third leg and the tied bases of the transistors of said first and second legs whereby the voltage mode of said frequency control signal is converted to a current mode signal.

Claim 11

In a phase locked loop, a phase comparator for receiving the input signal and providing an output, filtering means coupled to the output of the phase comparator and providing a filtered output serving as a frequency control signal and a voltage controlled oscillator coupled between the output of the filtering means and the phase comparator, said voltage controlled oscillator comprising multivibrator means including first and second transistors each having a base, collector and emitter, means connected to the collector of said first and second transistors for maintaining the voltage swings at the collectors of said first and second transistors equal and independent of the current level of said transistors and means for varying the frequency of oscillation of said multivibrator means in response to said frequency control signal including variable current source means coupled to the emitters of said first and second transistors, said current source means being responsive to said frequency control signal to vary the amount of current produced by said current source means to vary the output signal of the multivibrator whereby said output signal has a frequency variation which is linearly proportional to said variation of said current source means, said current source means including a common constant current source coupled to a current divider network having three legs, two of the legs being coupled to said emitters of said transistors of said multivibrator and a third leg carrying the remainder of the current of said common constant current source, and said current source means also including means responsive to said frequency control signal coupled to said three legs of said current divider network for varying the current in said two legs coupled to said emitters of said multivibrator transistors in an opposite sense relative to said variation of current in said third leg in response to said variation iN the magnitude of said frequency control signal whereby said common current source is maintained constant and said differential variation of currents of said legs stabilizes the temperature characteristics of said current source means.

Claim 12

In a phase locked loop, a phase comparator for receiving the input signal and providing an output, filtering means coupled to the output of the phase comparator and providing a filtered output serving as a frequency control signal and a voltage controlled oscillator coupled between the output of the filtering means and the phase comparator, said voltage controlled oscillator comprising multivibrator means including first and second transistors each having a base, collector and emitter, means connected to the collector of said first and second transistors for maintaining the voltage swings at the collectors of said first and second transistors equal and independent of the current level of said transistors and means for varying the frequency of oscillation of said multivibrator means in response to said frequency control signal including variable current source means coupled to the emitters of said first and second transistors, said current source means being responsive to said frequency control signal to vary the amount of current produced by said current source means to vary the output signal of the multivibrator whereby said output signal has a frequency variation which is linearly proportional to said variation of said current source means, said current source means including a common constant current source coupled to a current divider network having three legs, two of the legs being coupled to said emitters of said transistors of said multivibrator and a third leg carrying the remainder of the current of said common constant current source, and said current source means also including means responsive to said frequency control signal coupled to said three legs of said current divider network for varying the current in said two legs coupled to said emitters of said multivibrator transistors in an opposite sense relative to said variation of current in said third leg in response to said variation iN the magnitude of said frequency control signal whereby said common current source is maintained constant and said differential variation of currents of said legs stabilizes the temperature characteristics of said current source means.