Voltage controlled oscillator with selectable frequency range

• US 6,504,441 B1
• Filed: 11/08/2000
• Issued: 01/07/2003
• Est. Priority Date: 11/08/2000
• Status: Expired due to Term

• Current Assignee: MACOM Connectivity Solutions, LLC (MACOM Technology Solutions Holdings, Inc.)
• Original Assignee: Applied Micro Circuits Corporation (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Eker, Mehmet M.
• Primary Examiner(s): Mis, David C.
• Application Number:
  US09/708,915
• Time in Patent Office: 790 Days
• Field of Search: 331/57, 331/178, 331/179, 331/34, 331/108.B, 331/135, 331/136, 331/137, 331/175, 331/177.R
• US Class Current: 331/136
• CPC Class Codes: H03B 23/00 Generation of oscillations periodically swept over a predetermined frequency range angle-modulating circuits in general H03C3/00

Abstract

A frequency sweep voltage controlled oscillator (VCO), with a selectable range of output frequencies is provided. The VCO includes a frequency range circuit to accept an input signal, differentially delay the signal, and selectably sum the delayed signals to provide signals in discrete frequency ranges. A frequency sweep circuit accepts the signal output from the frequency range circuit, differentially delays the signal, and sums the delayed signal in such a way as to modify the previously selected frequency range. A method for generating a signal from a frequency sweep VCO is also provided.

Claims

1. A voltage controlled oscillator comprising:

a frequency range circuit with an input for receiving a differential input signal and an input for receiving a range control command, the frequency range circuit for delaying the differential input signal in accordance with the range control command to form a delayed differential signal; and

a frequency sweep circuit with an input for receiving the delayed differential signal and an input for receiving a converted control signal, the frequency sweep circuit for further delaying the delayed differential signal in accordance with the converted control signal to produce a feedback signal provided as the differential input signal to the frequency range circuit, the frequency sweep circuit comprising;

an analog multiplexor with a control input for receiving the converted control signal; and

a plurality of delay sections connected in parallel between the frequency range circuit and the analog multiplexor;

the analog multiplexor responsive to the converted control signal for forming the feedback signal by combining delayed signals produced by the plurality of delay sections.

2. A voltage controlled oscillator in accordance with claim 1, wherein a total delay, equal to the sum of the delay of the frequency range circuit and the delay of the frequency sweep circuit, determine a frequency of oscillation of the voltage controlled oscillator.

3. A voltage controlled oscillator in accordance with claim 2 wherein the frequency sweep circuit includes a first delay section to delay the delayed differential signal by a first delay and a second delay section to delay delayed differential signal by a second delay, less than the first delay, the analog multiplexor having an output to supply the feedback signal that is a variable sum of the signals having the first and second delays.

4. A voltage controlled oscillator in accordance with claim 3 wherein the frequency range circuit includes an input connected to the output of the frequency sweep circuit, the frequency range circuit having a third delay section to delay the differential input signal a third delay and a fourth delay section to delay the differential input signal a fourth delay, less than the third delay.

5. A voltage controlled oscillator in accordance with claim 4, wherein the frequency range circuit further comprises digital multiplexor having a first signal input connected to the output of the third delay section, a second signal input connected to the output of the fourth delay section, a control input to accept the range control commands, the digital multiplexor producing the delayed differential signal by passing a signal produced at the output of a selected delay section of the third delay section and the fourth delay section to pass a selected signal having a delay in accordance with the range control command.

6. A voltage controlled oscillator in accordance with claim 5, wherein the analog multiplexor of the frequency sweep circuit comprises a first signal input connected to the output of the first delay section, a second signal input connected to the output of the second delay section, a control input to accept the converted control signal, the multiplexor producing the feedback signal that is a sum of the delayed signals produced by the first and second delay sections in accordance with the converted control signals.

7. A voltage controlled oscillator in accordance with claim 6, wherein the first delay section of the frequency sweep circuit includes a first sequence of series connected delay elements and the second delay section of the frequency sweep circuit includes a second sequence of series connected delay elements.

8. A voltage controlled oscillator in accordance with claim 7, wherein the third delay section of the frequency range circuit includes a sequence of at least one series connected delay element.

9. A voltage controlled oscillator in accordance with claim 8, wherein the another multiplexor of the frequency range circuit accepts a predetermined plurality of discrete range control commands and the another multiplexor supplies delayed differential signals in a corresponding plurality of discrete frequency ranges in response to the range control commands.

10. A method of producing an oscillating output signal, the method comprising:

providing a differential input signal;

producing a plurality of delayed signals from the differential input signal;

providing a frequency range command;

delaying the differential input signal in accordance with the frequency range command by selecting one of the plurality of delayed signals;

delaying further the selected delayed signal by a plurality of delays to produce a plurality of delayed differential signals;

providing a control signal; and

combining, in accordance with the control signal, the plurality of delayed differential signals to form the output signal.

11. A method in accordance with claim 10, wherein the delaying further comprises delaying the selected signal through a plurality of parallel delay sections to form the plurality of delayed differential signals.

12. A method in accordance with claim 11, wherein the control signal is a differential control signals and wherein the combining comprises combining the plurality of delayed differential signals in an analog multiplexor by combining at least a portion of each of the plurality of delayed differential signals in accordance with a voltage difference between two signals of the differential control signal.

13. A method in accordance with claim 12, wherein the delaying the differential input signal comprises delaying the differential signal through at least two delay sections.

14. A method in accordance with claim 13, wherein at least one of the delay sections provides no delay.

15. A method in accordance with claim 14, wherein the delaying the differential input signal further comprises:

selecting a selected signal produced at an output of one of the delay sections having a delay corresponding to the frequency range command.