Crystal oscillator having input/output pins selectively used for analog or digital signals
First Claim
1. An analog and digital electronic circuit, comprising:
- a power lead, an input/output pin, and a switching circuit, the power lead coupled to the switching circuit and the switching circuit coupled to the input/output pin;
a first operating mode allowing analog communication with the analog and digital electronic circuit via the input/output pin when a first signal is applied to the power lead to control the switching circuit; and
a second operating mode allowing digital communication with the analog and digital electronic circuit via the input/output pin when a second signal is applied to the power lead to control the switching circuit.
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Accused Products
Abstract
A digital temperature compensated crystal oscillator (10) with pin multiplex control which includes: four analog I/O pins, a signal multiplex method which allows switchable digital communication via at least two of the analog I/O pins (20,28), and an external mode selector (12) which operates through the power leads. Changes in the power voltage level selects the TCXO (10) to operate in a normal or communication operating mode. In the normal operating mode the TCXO operates in a normal analog manner. In the communication mode, the analog functions of the I/O pins (20,28) are switched out and digital functions are allowed on the same I/O pins (20,28). The use of the same I/O pins (20,28) for switchable analog and digital signals saves size and cost, and prevents the inadvertent access to the digital functions of the TCXO (10) by customers in the field.
83 Citations
21 Claims
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1. An analog and digital electronic circuit, comprising:
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a power lead, an input/output pin, and a switching circuit, the power lead coupled to the switching circuit and the switching circuit coupled to the input/output pin; a first operating mode allowing analog communication with the analog and digital electronic circuit via the input/output pin when a first signal is applied to the power lead to control the switching circuit; and a second operating mode allowing digital communication with the analog and digital electronic circuit via the input/output pin when a second signal is applied to the power lead to control the switching circuit.
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2. A temperature compensated crystal oscillator circuit, comprising:
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a crystal oscillator electrically coupled to a first and a second I/O pin via respective first and second analog lines; a control logic circuit and an interface circuit electrically coupled to a digital data-in line, a digital data-out line, and a digital clock-input; a first and a second I/O control having respective first and second control lines each of which are electrically coupled to the control logic circuit; the first I/O control is electrically coupled to the first I/O pin and switchably connects the first I/O pin between the digital data-in line and the digital data-out line each of which are electrically coupled to the interface circuit; the second I/O control is electrically coupled to the second I/O pin and switchably connects the second I/O pin to the digital clock-input line which is coupled to the interface circuit; and the interface circuit is adapted to input a digital data-in signal from the first I/O pin via the first I/O control, receive a digital clock-input signal from the second I/O pin via the second I/O control, and output a digital data-out signal to the first I/O pin via the first I/O control, the digital clock-input line for clocking the data-in and data-out signals respectively into and out of the interface circuit. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A temperature compensated crystal oscillator circuit, comprising:
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a crystal oscillator electrically coupled to a first and a second I/O pin via respective first and second analog lines; a control logic circuit and a serial interface circuit electrically coupled to a digital serial data-in line, a digital serial data-out line, and a digital shift-clock-input line; a first and a second I/O control having respective first and second control lines each of which are electrically coupled to the control logic circuit; the first I/O control is electrically coupled to the first I/O pin and switchably connects the first I/O pin between the digital serial data-in line and the digital serial data-out line each of which are electrically coupled to the serial interface circuit; the second I/O control is electrically connected to the second I/O pin and switchably connects the second I/O pin between a digital shift-clock-input line which is coupled to the serial interface circuit and an analog RF output line which is coupled to an output of the crystal oscillator, the crystal oscillator is adapted to receive an analog tuning signal from the first I/O pin via the first I/O control and a DC warp line which electrically connects the first I/O pin to the crystal oscillator; the serial interface circuit is adapted to receive a digital serial data-in signal from the first I/O pin via the first I/O control, receive a control, and transmit a digital serial data-out signal to the first I/O pin via the first I/O control, the digital shift-clock-input signal for clocking the serial data-in and data-out signals into and out of the serial interface circuit; a mode selector is electrically coupled to the control logic circuit, the mode selector generating a switching signal which directs the control logic circuit to switch the first and second I/O controls via the first and second control lines, respectively; a first control potential generated by the mode selector causing the second I/O control to couple the analog output of the crystal oscillator to the second I/O pin; and a second control potential generated by the mode selector causing the first I/O control to couple the first and I/O pin to the serial interface circuit through one of the digital serial data-in and data-out lines, and causing the second I/O control to couple the digital shift-clock-input signal between the second I/O pin and the serial interface circuit. - View Dependent Claims (15, 16, 17, 18)
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19. A method for providing multiplexed analog and digital communication on an I/O pin of a temperature compensated crystal oscillator, comprising the steps of:
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providing a temperature compensated crystal oscillator including a power lead, an I/O pin, and a switching circuit having at least a first and second operating mode, the switching circuit being electrically coupled to the power lead and the I/O pin; applying a first control potential to the power lead such that the switching circuit switches to the first operating mode which allows analog communication with the temperature compensated crystal oscillator on the I/O pin; and applying a second control potential to the power lead such that the switching circuit switches to the second operating mode which allows digital communication with the temperature compensated crystal oscillator on the I/O pin. - View Dependent Claims (20)
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21. A communication device, comprising:
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a receiver circuit; a local oscillator circuit for generating local oscillator signals including a reference oscillator comprising; a power lead, an I/O pin, and a switching circuit, the power lead coupled to the switching circuit and the switching circuit coupled to the I/O pin; a first operating mode allowing analog communication with the reference oscillator via the I/O pin when a first signal is applied to the power lead to control the switching circuit; and a second operating mode allowing digital communication with the reference oscillator via the I/O pin when a second signal is applied to the power lead to control the switching circuit.
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Specification