Clock offset compensator
First Claim
1. A device that communicates with a host, comprising:
- a transmitter;
a receiver;
a clock generator that generates a signal having a local clock frequency;
a clock recovery circuit that communicates with said receiver and that recovers a host clock frequency from data received from said host by said receiver;
a frequency offset circuit that communicates with said clock recovery circuit and said clock generator and that generates a frequency offset based on said clock frequency and said recovered host clock frequency;
a frequency compensator that compensates a frequency of said transmitter using said frequency offset,wherein said frequency compensator includes a low pass filter that communicates with said frequency offset circuit, said frequency compensator includes an accumulator that communicates with said low pass filter and that generates a phase offset, said frequency compensator includes an interpolator that receives a local phase from said clock generator and said phase offset from said accumulator, and said interpolator outputs a compensated clock signal to said transmitter;
a summer having a first input that communicates with an output of said lowpass filter and an output that communicates with an input of said accumulator; and
a frequency modulation generator that communicates with a second input of said summer and that selectively generates a spread spectrum modulation signal when spread spectrum operation is enabled and a constant signal when spread spectrum operation is disabled.
7 Assignments
0 Petitions
Accused Products
Abstract
A device communicates with a host and includes a transmitter, a receiver and a clock generator that generates a signal having a local clock frequency. A clock recovery circuit communicates with the receiver and recovers a host clock frequency from data received from the host by the receiver. A frequency offset circuit communicates with the clock recovery circuit and the clock generator and generates a frequency offset based on the clock frequency and the recovered host clock frequency. A frequency compensator compensates a frequency of the transmitter using the frequency offset. The host and the device may communicate using a serial ATA standard. Frequency compensation can be performed during spread spectrum operation.
-
Citations
35 Claims
-
1. A device that communicates with a host, comprising:
-
a transmitter; a receiver; a clock generator that generates a signal having a local clock frequency; a clock recovery circuit that communicates with said receiver and that recovers a host clock frequency from data received from said host by said receiver; a frequency offset circuit that communicates with said clock recovery circuit and said clock generator and that generates a frequency offset based on said clock frequency and said recovered host clock frequency; a frequency compensator that compensates a frequency of said transmitter using said frequency offset, wherein said frequency compensator includes a low pass filter that communicates with said frequency offset circuit, said frequency compensator includes an accumulator that communicates with said low pass filter and that generates a phase offset, said frequency compensator includes an interpolator that receives a local phase from said clock generator and said phase offset from said accumulator, and said interpolator outputs a compensated clock signal to said transmitter; a summer having a first input that communicates with an output of said lowpass filter and an output that communicates with an input of said accumulator; and a frequency modulation generator that communicates with a second input of said summer and that selectively generates a spread spectrum modulation signal when spread spectrum operation is enabled and a constant signal when spread spectrum operation is disabled. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A communication system including:
-
a host including a host transmitter, a host receiver, and a host clock generator that generates a signal having a host clock frequency; a device that communicates with said host using a serial ATA standard and that includes a device transmitter, a device receiver, a device clock generator that generates a local clock frequency, a clock recovery circuit that recovers said host clock frequency from data received from said host by said device receiver, a frequency offset circuit that generates a frequency offset based on said local clock frequency and said recovered host clock frequency, and a frequency compensator that compensates a frequency of said device transmitter using said frequency offset, wherein said frequency compensator includes a low pass filter that communicates with said frequency offset circuit, said frequency compensator includes an accumulator that communicates with said low pass filter and that generates a phase offset, and said frequency compensator includes an interpolator that receives a local phase from said device clock generator and said phase offset from said accumulator; a summer having a first input that communicates with an output of said low pass filter and an output that communicates with an input of said accumulator; and a frequency modulation generator that communicates with a second input of said summer and that selectively generates a spread spectrum modulation signal when spread spectrum operation is enabled and a constant signal when spread spectrum operation is disabled. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. A frequency offset compensator for a device that communicates with a host, comprising:
-
a clock data recovery and frequency offset calculator that generates a frequency offset; a frequency modulation generator that generates a spread spectrum modulation signal when spread spectrum operation is enabled; and a summer that adds said frequency offset and an output of said frequency modulation generator to generate a summed frequency offset; a conversion circuit that converts said summed frequency offset to a phase offset. - View Dependent Claims (15, 16)
-
-
17. A device that communicates with a host, comprising:
-
transmitting means for transmitting data to said host;
receiving means for receiving data from said host;clock generating means for generating a signal having a local clock frequency; clock recovery means for recovering a host clock frequency from data received from said host by said receiving means; frequency offset means for generating a frequency offset based on said clock frequency and said recovered host clock frequency; frequency compensating means for compensating a frequency of said transmitting means using said frequency offset, wherein said frequency compensating means includes filtering means for filtering an output of said frequency offset means, said frequency compensating means further includes accumulating means that communicates with said filtering means for generating a phase offset, and said frequency compensating means further includes interpolating means that receives a local phase from said clock generating means and said phase offset from said accumulating means for generating a compensated clock signal for said transmitting means; frequency modulation generating means for selectively generating a spread spectrum modulation signal when spread spectrum operation is enabled and a constant signal when spread spectrum operation is disabled; and summing means for summing an output of said filtering means and said frequency modulation generating means and having an output that communicates with an input of said accumulating means. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
-
24. A communication system including:
-
a host including host transmitting means for transmitting data, host receiving means for receiving data, and host clock generating means for generating a signal having a host clock frequency; a device that communicates with said host using a serial ATA standard and that includes device transmitting means for transmitting data, device receiving means for receiving data, device clock generating means for generating a local clock frequency, clock recovery means for recovering said host clock frequency from data received from said host by said device receiving means, frequency offset means for generating a frequency offset based on said local clock frequency and said recovered host clock frequency, and frequency compensating means for compensating a frequency of said device transmitting means based on said frequency offset, wherein said frequency compensating means includes filtering means for filtering said frequency offset, said frequency compensating means further includes accumulating means that communicates with said filtering means for generating a phase offset, and said frequency compensating means includes interpolating means for receiving a local phase from said device clock generating means and said phase offset from said accumulating means; frequency modulation generating means for selectively generating a spread spectrum modulation signal when spread spectrum operation is enabled and a constant when spread spectrum operation is disabled; and summing means for summing an output of said filtering means and said frequency modulation generating means and having an output that communicates with an input of said accumulating means. - View Dependent Claims (25, 26, 27, 28, 29)
-
-
30. A frequency offset compensator for a device that communicates with a host, comprising:
offset calculating means for generating a frequency offset;
frequency modulation generating means for generating a spread spectrum modulation signal when spread spectrum operation is enabled;
summing means for generating a summed frequency offset by summing said frequency offset and said spread spectrum modulation signal; and
conversion means for converting said summed frequency offset to a phase offset.- View Dependent Claims (31, 32)
-
33. A method for providing frequency offset compensation for a device that communicates with a host, comprising:
-
generating a frequency offset; generating a spread spectrum modulation signal when spread spectrum operation is enabled; summing said frequency offset and said spread spectrum modulation signal to generate a summed frequency offset; and converting said summed frequency offset to a phase offset. - View Dependent Claims (34, 35)
-
Specification