Temperature stabilized CMOS oscillator circuit
First Claim
1. A temperature stabilized CMOS oscillator circuit having stabilized gain over temperature comprising:
- a crystal oscillator for providing an output signal said crystal oscillator further comprising a CMOS oscillator transistor; and
a bias circuit connected to the crystal oscillator as a current source to provide a supply current to the CMOS oscillator transistor and to vary the supply current over temperature to provide the stabilized gain, wherein the bias circuit further comprises;
a primary current mirror connected to the crystal oscillator to provide a supply current to the CMOS oscillator transistor; and
a secondary current mirror connected to the primary current mirror to divert current from the primary current mirror to vary the supply current over temperature.
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Abstract
A temperature stabilized CMOS oscillator circuit modifies the gain of a CMOS oscillator transistor to cancel the gain variation over temperature using a bias circuit. The bias circuit utilizes a combination of two current mirrors to establish a temperature compensating supply current to a CMOS oscillator transistor. A primary current mirror and a temperature variable resistor establish a current in the current mirror output to the CMOS oscillator transistor. A secondary current mirror and a temperature variable resistor divert current from the primary current mirror over temperature to vary the current mirror output to the CMOS oscillator transistor to compensate for its gain variation.
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Citations
7 Claims
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1. A temperature stabilized CMOS oscillator circuit having stabilized gain over temperature comprising:
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a crystal oscillator for providing an output signal said crystal oscillator further comprising a CMOS oscillator transistor; and
a bias circuit connected to the crystal oscillator as a current source to provide a supply current to the CMOS oscillator transistor and to vary the supply current over temperature to provide the stabilized gain, wherein the bias circuit further comprises;
a primary current mirror connected to the crystal oscillator to provide a supply current to the CMOS oscillator transistor; and
a secondary current mirror connected to the primary current mirror to divert current from the primary current mirror to vary the supply current over temperature. - View Dependent Claims (2, 3, 4)
a primary pair of CMOS transistors connected as a current mirror current source; and
a resistor with a low positive temperature coefficient connected to the primary pair of CMOS transistors to set a primary current mirror current that sets the supply current.
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4. The temperature stabilized CMOS oscillator of claim 3 wherein the secondary current mirror comprises:
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a secondary pair of CMOS transistors connected as a secondary current mirror current source; and
a resistor with a high positive temperature coefficient connected to the secondary pair of CMOS transistors to set a secondary current mirror current that diverts current from the primary current mirror current.
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5. A temperature stabilized CMOS oscillator circuit having stabilized gain over temperature comprising:
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a crystal oscillator for providing an output signal said crystal oscillator further comprising a CMOS oscillator transistor;
a primary current mirror connected to the crystal oscillator to provide a supply current to the CMOS oscillator transistor; and
a secondary current mirror connected to the primary current mirror to ,divert current from the primary current mirror to vary the supply current over temperature to provide the stabilized gain. - View Dependent Claims (6, 7)
a primary pair of CMOS transistors connected as a current mirror current source; and
a resistor with a low positive temperature coefficient connected to the primary pair of CMOS transistors to set a primary current mirror current that sets the supply current.
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7. The temperature stabilized CMOS oscillator of claim 6 wherein the secondary current mirror comprises:
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a secondary pair of CMOS transistors connected as a secondary current mirror current source; and
a resistor with a high positive temperature coefficient connected to the secondary pair of CMOS transistors to set a secondary current mirror current that diverts current from the primary current mirror current.
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Specification