Programmable phase locked loop circuit and method of programming same

Claim 1

A programmable phase locked loop circuit comprising: phase detection means being characterized by a phase error gain constant K p , and adapted for detecting the phase error between first and second input signals and generating as output a phase error signal representative of said phase error; a loop filter characterized by one or more phase margin contributing time constants T i and being operably associated with said phase detection means to receive as input said phase error signal and produce as output a control signal,each said phase margin contributing time constant T i being functionally dependent on an active element in said loop filter, and each said active element having a time constant contributing property functionally dependent on said phase error gain constant K p , and said phase error gain constant K p being proportional to a programmable current in said phase detection means, and said time constant contributing property of each said active element being functionally dependent on said programmable current; a variable frequency oscillator being characterized by an oscillator gain constant K o , and producing as output said second input signal having a frequency controlled by said control signal; said programmable phase locked loop circuit having, when programmed, a cross-over frequency, a phase margin at said cross-over frequency determined by said phase margin contributing time constants, and an open loop gain K m proportional to the product of said phase error gain constant K p and said oscillator gain constant; and programming means for programming the cross-over frequency of said programmable phase locked loop circuit and the phase margin thereof at said cross-over frequency, by adjusting said programmable current to one of a plurality of different programmable current values, whereby the cross-over frequency of said programmable phase locked loop circuit is automatically programmed to one of said plurality of different cross-over frequencies while the phase margin of said programmable phase locked loop circuit is maintained substantially constant at each of said plurality of different cross-over frequencies.

Claim 5

A method of electronically programming a programmable phase locked loop circuit, comprising the steps: (a) providing a device employing a programmable phase locked loop circuit, said programmable phase locked loop circuit including (1) phase detection means being characterized by a phase error gain constant K p , and adapted for detecting the phase error between first and second input signals and generating as output a phase error signal representative of said phase error, (2) a loop filter characterized by one or more phase margin contributing time constants T i and being operably associated with said phase detection means to receive as input said phase error signal and produce as output a control signal,each said phase margin contributing time constant T i being functionally dependent on an active element in said loop filter, and each said active element having a time constant contributing property functionally dependent on said phase error gain constant K p , and said phase error gain constant K p being proportional to a programmable current in said phase detection means, and said time constant contributing property of each said active element being functionally dependent on said programmable current, (3) a variable frequency oscillator being characterized by an oscillator gain constant K o , and producing as output said second input signal having a frequency controlled by said control signal, (4) said programmable phase locked loop circuit having, when programmed, a cross-over frequency, a phase margin at said cross-over frequency determined by said phase margin contributing time constants, and an open loop gain K m proportional to the product of said phase error gain constant K p and said oscillator gain constant, and (5) programming means for programming the cross-over frequency of said programmable phase locked loop circuit and the phase margin thereof at said cross-over frequency, by setting said programmable current to one of a plurality of different programmable current values, whereby the cross-over frequency of said programmable phase locked loop circuit is automatically programmed to one of said plurality of different cross-over frequencies while the phase margin of said programmable phase locked loop circuit is maintained substantially constant at each of said plurality of different cross-over frequencies; and (b) programming said cross-over frequency to a selected one of said plurality of different cross-over frequencies by solely setting said programmable current to one of said plurality of different programmable current values, whereby the cross-over frequency of said programmable phase locked loop circuit is automatically programmed to said selected cross-over frequency while the phase margin of said programmable phase locked loop circuit is maintained substantially constant.

Claim 6

A method of electronically programming a programmable phase locked loop circuit, comprising the steps: (a) providing a device employing a programmable phase locked loop circuit, said programmable phase locked loop circuit including (1) phase detection means being characterized by a phase error gain constant K p , and adapted for detecting the phase error between first and second input signals and generating as output a phase error signal representative of said phase error, (2) a loop filter characterized by one or more phase margin contributing time constants T i and being operably associated with said phase detection means to receive as input said phase error signal and produce as output a control signal,each said phase margin contributing time constant T i being functionally dependent on an active element in said loop filter, and each said active element having a time constant contributing property functionally dependent on said phase error gain constant K p , and said phase error gain constant K p being proportional to a programmable current in said phase detection means, and said time constant contributing property of each said active element being functionally dependent on said programmable current, (3) a variable frequency oscillator being characterized by an oscillator gain constant K o , and producing as output said second input signal having a frequency controlled by said control signal, (4) said programmable phase locked loop circuit having, when programmed, a cross-over frequency, a phase margin at said cross-over frequency determined by said phase margin contributing time constants, and an open loop gain K m proportional to the product of said phase error gain constant K p and said oscillator gain constant, and (5) programming means for programming the cross-over frequency of said programmable phase locked loop circuit and the phase margin thereof at said cross-over frequency, by setting said programmable current to one of a plurality of different programmable current values, whereby the cross-over frequency of said programmable phase locked loop circuit is automatically programmed to one of said plurality of different cross-over frequencies while the phase margin of said programmable phase locked loop circuit is maintained substantially constant at each of said plurality of different cross-over frequencies; and (b) programming said cross-over frequency to a selected one of said plurality of different cross-over frequencies by solely setting said programmable current to one of said plurality of different programmable current values, whereby the cross-over frequency of said programmable phase locked loop circuit is automatically programmed to said selected cross-over frequency while the phase margin of said programmable phase locked loop circuit is maintained substantially constant.