Claims
- 1. A programmable damping circuit for controlling damping factor of a phase-locked loop, the programmable damping circuit comprising:
- a phase detector having an input for receiving an input signal of said programmable damping circuit;
- a charge pump coupled to an output of said phase detector;
- a loop filter consisting of a capacitor coupled directly to a first terminal at an output of said charge pump, and at a second terminal to ground;
- a summing node coupled to said first terminal of said loop filter capacitor;
- a variable gain amplifier having an input coupled to said output of said phase detector, said variable gain amplifier having an output coupled to said summing node, said variable gain amplifier having a gain controlled by a control signal, wherein a voltage of an output signal provided by said summing node is adjusted by controlling said gain of said variable gain amplifier for controlling said damping factor of said phase-locked loop.
- 2. The circuit of claim 1 wherein said charge pump comprises a transconductance element.
- 3. The circuit of claim 2 wherein said phase detector is a type B phase detector.
- 4. The circuit of claim 1 wherein said phase detector is a type B phase detector.
- 5. The circuit of claim 3 wherein said type B phase detector is used in a sampled data system.
- 6. The circuit of claim 3 wherein said sampled data system is a Partial Response Maximum Likelihood channel for hard disk drives.
- 7. The circuit of claim 1 wherein said charge pump is a transconductance type charge pump.
- 8. The circuit of claim 3 wherein said charge pump is a transconductance type charge pump.
- 9. The circuit of claim 4 wherein said type B phase detector is used in a sampled data system.
- 10. The circuit of claim 9 wherein said sampled data system is a Partial Response Maximum Likelihood channel for hard disk drives.
- 11. The circuit of claim 4 wherein said charge pump is a transconductance type charge pump.
Parent Case Info
This is a continuation of application Ser. No. 08/241,271 filed on May 9, 1994 and now abandoned.
US Referenced Citations (4)
Continuations (1)
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Number |
Date |
Country |
Parent |
241271 |
May 1994 |
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