Digital clock frequency multiplier
View Patent ↗A digital clock frequency multiplier ( 100 ) for increasing an input frequency of an input clock signal includes a generator ( 102 ) that receives the input clock signal and a high frequency digital signal. The generator ( 102 ) divides a count (N hf ) of a number of cycles of the high frequency digital signal in one period of the input clock signal by a predetermined multiplication factor (MF) for generating an output clock signal. The output clock signal has a predetermined output frequency.
1. A digital clock frequency multiplier for increasing an input frequency of an input clock signal, the digital clock frequency multiplier comprising:
a generator that receives the input clock signal and a high frequency digital signal and divides a count (N hf ) of a number of cycles of the high frequency digital signal in one period of the input clock signal by a predetermined multiplication factor (MF) for generating an output clock signal having a predetermined output frequency, wherein the generator includes:
a first counter that receives the input clock signal and the high frequency digital signal and generates the count N hf ;
a divider coupled to the first counter that divides the count N hf by the predetermined multiplication factor (ME) to determine a number of cycles (C) of the high frequency digital signal in one period of the output clock signal;
a first latch coupled to the divider that stores predetermined values of the number of cycles C;
a second counter that receives the high frequency digital signal and counts the cycles thereof;
a comparator, coupled to the second counter and the first latch, that compares the counted cycles from the second counter with the predetermined values of the number of cycles C stored in the first latch;
an edge generator coupled to the comparator for generating pulse signals when the counted cycles from the second counter are equal to the predetermined values of the number of cycles C stored in the first latch; and
an output clock generator coupled to the edge generator for receiving the pulse signals and generating the output clock signal therefrom.
2. The digital clock frequency multiplier of claim 1 , wherein the predetermined multiplication factor has a value ranging from about 2 to about 1023.
3. The digital clock frequency multiplier of claim 1 , wherein the first latch stores values equal to the number of cycles C and half the number of cycles C/2.
4. The digital clock frequency multiplier of claim 3 , wherein the output clock generator combines the pulse signals generated when the counted cycles from the second counter are equal to the number of cycles C and half the number of cycles C/2 to generate the output clock signal.
5. The digital clock frequency multiplier of claim 1 , wherein the generator further comprises a frequency divider coupled to the output clock generator for dividing an output frequency of the output clock signal by two.
6. The digital clock frequency multiplier of claim 5 , wherein the generator further comprises a multiplexer coupled to the output clock generator and the frequency divider for selecting the output clock signal having the predetermined output frequency based on the predetermined multiplication factor.
7. The digital clock frequency multiplier of claim 1 , wherein the divider increments the number of cycles C when a value of a remainder (R) from the division performed by the divider is greater than one-half.
8. The digital clock frequency multiplier of claim 1 , herein the count N hf is updated at predetermined intervals in one clock cycle of the input clock signal.
9. The digital clock frequency multiplier of claim 8 , wherein the predetermined intervals are based on voltage and temperature (VT) variations.
10. A digital clock frequency multiplier for increasing an input frequency of an input clock signal, the digital clock frequency multiplier comprising:
a generator that receives the input clock signal and a high frequency digital signal and divides a count (N hf ) of a number of cycles of the high frequency digital signal in one period of the input clock signal by a predetermined multiplication factor (MF) for generating an output clock signal having a predetermined output frequency, wherein the generator includes:
a first counter that receives the input clock signal and the high frequency digital signal and generates the count N hf ;
a divider coupled to the first counter that divides the count N hf by the predetermined multiplication factor to determine a number of cycles (C) of the high frequency digital signal in one period of the clock signal;
a first latch coupled to the divider that stores predetermined values of the number of cycles C and C/2;
a second counter that receives the high frequency digital signal and counts the cycles thereof;
a comparator coupled to the first latch and the second counter that compares the counted cycles from the second counter with the predetermined values of the number of cycles C stored in the first latch;
an edge generator coupled to the comparator for generating pulse signals when the counted cycles from the second counter are equal to the predetermined values of the number of cycles C and C/2 stored in the first latch; and
an output clock generator coupled to the edge generator for receiving the pulse signals and generating the output clock signal therefrom.
11. The digital clock frequency multiplier of claim 10 , wherein the predetermined multiplication factor MF has a value ranging from about 2 to about 1023.
12. The digital clock frequency multiplier of claim 10 , wherein the count N hf is updated at predetermined intervals in one clock cycle of the input clock signal.
13. A method for generating an output clock signal, the method comprising:
receiving an input clock signal and a high frequency digital signal;
generating a count (N hf ) of a number of cycles of the high frequency digital signal in one period of the input clock signal;
dividing the count N hf by a predetermined multiplication factor (MF) to determine a number of cycles (C) of the high frequency digital signal in one period of the output clock signal;
generating an edge for each cycle at C and C/2;
combining the generated edges to generate the output clock signal having a predetermined output frequency; and
incrementing the number of cycles C when a value of a remainder (R) from the division is greater than half.
14. The method for generating an output clock signal of claim 13 , further comprising latching the count N hf .
15. The method for generating an output clock signal of claim 14 , further comprising updating the count N hf at predetermined intervals in one clock cycle of the input clock signal.