Temperature and voltage compensation for transistorized vco control circuit

Claim 2

In combination with a transistorized DC amplifier energized by a source of supply voltage and connected between a source of input voltage and a load, a circuit to compensate for ambient temperature and supply voltage variations comprising a transistorized regulator energized by said source of supply voltage and having an output terminal connected to a reference terminal of said load, said load comprising a voltage responsive variable reactance means having a control terminal connected to the output of said DC amplifier and a reference terminal comprising the reference terminal of said load connected to the output of said regulator and a voltage-controlled oscillator connected to said control terminal of said variable reactance means and having phase and frequency control means including said variable reactance means, and circuit means connecting the output of said regulator as a source of bias voltage for said DC amplifier.

Claim 3

The combination of claim 1 wherein said variable reactance means comprises a varactor, and said regulator comprises a transistor having collector, base and emitter electrodes, a first resistance means connected between the collector electrode of said regulator transistor and said source of supply voltage, a second resistance means connected between the emitter of said regulator transistor and ground, and a third resistance means connected in a feedback path between the collector and base electrodes of said regulator transistor, the collector of said regulator transistor being connected to the reference terminal of said varactor and through said bias circuit means to the input of said transistorized DC amplifier for providing base bias voltage therefor, and the amount of compensation provided by said regulator being determined by the selected values of said first, second and third resistance means.

Claim 4

The combination of claim 2 further including a phase detector having fIrst and second input means and an output, means for coupling a feedback signal from the output of said oscillator to the first input means of said phase detector, and means for applying a reference signal to the second input means of said phase detector, and wherein: the output of said phase detector is connected to the input of said DC amplifier as said source of input voltage; said phase detector provides a high-input impedance for said DC amplifier; and said circuit means for providing base bias voltage to said DC amplifier comprises means connecting the collector of said regulator transistor to the first input means of said phase detector, a DC circuit path through said phase detector from its first input means to its output, and the connection of the output of said phase detector to the input of said DC amplifier; said combination thereby comprising a temperature- and voltage-compensated phase lock loop in which said phase detector is operative in response to an undesired difference in phase between said reference signal and said feedback signal to produce an error signal which is applied via said DC amplifier to said varactor for controlling the phase and frequency of said oscillator.

Claim 5

The combination of claim 3 wherein said DC amplifier is a transistorized Darlington amplifier.

Claim 6

The combination of claim 1 further including a phase detector having first and second input means and an output, said detector output being connected to the input of said DC amplifier as said source of input voltage, means for coupling a feedback signal from the output of said oscillator to the first input means of said phase detector, and means for applying a reference signal to the second input means of said phase detector, said combination thereby comprising a temperature- and voltage-compensated phase lock loop in which said phase detector is operative in response to an undesired difference in phase between said reference signal and said feedback signal to produce an error signal which is applied via said DC amplifier to said variable reactance means for controlling the phase and frequency of said oscillator.

Claim 7

The combination of claim 5 wherein said circuit means for providing bias voltage to said DC amplifier comprises means connecting the output of said regulator to the first input means of said phase detector, a DC circuit path through said phase detector from its first input means to its output, and the connection of the output of said phase detector to the input of said DC amplifier.

Claim 8

The combination of claim 6 wherein said means connecting the output of said regulator to the first input means of said phase detector includes a variable-voltage divider for adjusting the bias applied to said DC amplifier in the absence of a reference signal to thereby establish the free-running frequency of said oscillator.

Claim 9

In a color television receiver including means for deriving chrominance information signals from a subcarrier signal modulated by the chrominance information, said means including a chroma amplifier, a demodulator, and a phase lock loop including a phase detector connected to said chroma amplifier and a voltage controlled oscillator connected to said demodulator and to said phase detector, a circuit for controlling said oscillator comprising: a transistorized DC amplifier having an input connected to said phase detector and an output; a transistorized regulator having an output; a source of supply voltage connected to said DC amplifier and said regulator for energization thereof; a voltage responsive variable reactance means having an input connected to the output of said DC amplifier and an output connected to said oscillator for controlling the phase and frequency thereof; and circuit means connecting the output of said regulator to said variable reactance means and as a source of bias voltage for said DC amplifier for compensating for ambient temperature and supply voltage variations.

Claim 10

In a color television receiver including means for deriving chrominance information signals from a subcarrier signal modulated by the chrominance information, said means including a chroma amplifier, a demodulator, and a phase lock loop including a phase detector connected to said chroma amplifier and a voltage controlled oscillator connected to said demodulator and to said phase detector, a circuit for controlling said oscillator comprising: a transistorized DC amplifier having an input connected to said phase detector and an output; a transistorized regulator having an output; a source of supply voltage connected to said DC amplifier and said regulator for energization thereof; a voltage responsive variable reactance means having an input connected to the output of said DC amplifier and an output connected to said oscillator for controlling the phase and frequency thereof; and circuit means connecting the output of said regulator to said variable reactance means and as a source of bias voltage for said DC amplifier for compensating for ambient temperature and supply voltage variations.

Claim 11

The circuit of claim 8 wherein said variable reactance means includes a varactor diode connected between the output of said DC amplifier and the output of said regulator.

Claim 12

The circuit of claim 9 wherein said transistorized regulator is a transistor amplifier the gain of which is selected to maintain a substantially constant voltage difference across said varactor diode over selected ranges of supply voltage and ambient temperature variations when the voltage provided at the input of said DC amplifier by said phase detector is constant.

Claim 13

The circuit of claim 8 wherein said circuit means connecting the output of said regulator as a source of bias voltage for said DC amplifier includes means connecting the output of said regulator to said phase detector, said phase detector providing a DC bias path therethrough to the input of said DC amplifier.