Low leakage local oscillator system
First Claim
1. Local oscillator apparatus comprising communication signal terminals (LNA_IN, LNA_INX;
- RF_OUT, RF_OUTN) for a communication signal, controlled frequency oscillator means (204;
404) for producing a local oscillator signal, reference frequency means (210;
410) for producing a reference frequency signal, feedback loop means (207-209;
407-409) for selecting and adjusting the frequency (fVCO) of said local oscillator signal relative to the frequency (fxtal) of said reference frequency signal, said feedback loop means (207-209;
407-409) including fractional-number dividing means (208;
408) for dividing said reference frequency by a programmable fractional number and supplying a feedback signal (VTUNE) to control the frequency (fVCO) of said oscillator means (204;
404), first frequency divider means (205;
405) for dividing the frequency of said local oscillator signal by a first division factor (M) to produce a conversion signal, where the frequency (FILO) of said conversion signal is at least approximately equal to the frequency (fRF) of said communication signal, and conversion means (202, 203;
402, 403) responsive to said conversion signal for converting between said communication signal and a base-band signal, characterised in that second frequency divider means (206;
406) for dividing the frequency of said local oscillator signal by a second division factor (N) is connected in said feedback loop means (207-209;
407-409) between said controlled frequency oscillator means (204;
404) and said fractional-number dividing means (208;
408) so that said fractional-number dividing means (208;
408) is responsive to the relative values of said reference frequency divided by said programmable fractional number and said frequency of said local oscillator signal (fVCO) divided by said second division factor (N), where the first division factor (M) is different to the second division factor (N) and the ratios between said first and second division factors (M/N, N/M) are fractional.
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Accused Products
Abstract
Local oscillator apparatus comprising communication signal terminals (LNA IN, LNA INX; RF OUT,RF OUTN) for a communication signal, especially in a receiver or a transmitter, and a controlled frequency oscillator (204; 404) for producing a local oscillator signal. The local oscillator also includes a reference frequency generator (210; 410) and a feedback loop (208;408) for selecting and adjusting the frequency (fVCO) of the local oscillator signal relative to the frequency (fxtal) of said reference frequency signal. A first frequency divider (205; 405) divides the frequency of the local oscillatr signal by a first division factor (M) to produce a conversion signal, where the frequency (FILO) of said conversion signal is at least approximately equal to the frequency (fRF) of the communication signal, and conversion means (202,203; 402, 403) responsive to the conversion signal converts between said communication signal and a base-band signal. A second frequency divider (206;406) divides the frequency of the local oscillator signal by a second division factor (N) and is connected in the feedback loop, where the first division factor (N) is different to the second division factor (M) and the ratios between said first and second division factors (M/N, N/M) are fractional.
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Citations
13 Claims
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1. Local oscillator apparatus comprising communication signal terminals (LNA_IN, LNA_INX;
- RF_OUT, RF_OUTN) for a communication signal, controlled frequency oscillator means (204;
404) for producing a local oscillator signal, reference frequency means (210;
410) for producing a reference frequency signal, feedback loop means (207-209;
407-409) for selecting and adjusting the frequency (fVCO) of said local oscillator signal relative to the frequency (fxtal) of said reference frequency signal, said feedback loop means (207-209;
407-409) including fractional-number dividing means (208;
408) for dividing said reference frequency by a programmable fractional number and supplying a feedback signal (VTUNE) to control the frequency (fVCO) of said oscillator means (204;
404), first frequency divider means (205;
405) for dividing the frequency of said local oscillator signal by a first division factor (M) to produce a conversion signal, where the frequency (FILO) of said conversion signal is at least approximately equal to the frequency (fRF) of said communication signal, and conversion means (202, 203;
402, 403) responsive to said conversion signal for converting between said communication signal and a base-band signal,characterised in that second frequency divider means (206;
406) for dividing the frequency of said local oscillator signal by a second division factor (N) is connected in said feedback loop means (207-209;
407-409) between said controlled frequency oscillator means (204;
404) and said fractional-number dividing means (208;
408) so that said fractional-number dividing means (208;
408) is responsive to the relative values of said reference frequency divided by said programmable fractional number and said frequency of said local oscillator signal (fVCO) divided by said second division factor (N), where the first division factor (M) is different to the second division factor (N) and the ratios between said first and second division factors (M/N, N/M) are fractional.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- RF_OUT, RF_OUTN) for a communication signal, controlled frequency oscillator means (204;
Specification