US 6,912,380 B2 · PLL circuit and wireless mobile station with that PLL circuit

Abstract

In a PLL circuit, and a wireless mobile station with that PLL circuit, an LPF charging constant current source, a discharging constant current source and a high-speed charging constant current source are connected to an output terminal of a phase comparator with current mode output. When a convergence frequency of the PLL circuit is low, an input voltage of a VCO is increased from OV so as to be converged by using the constant current source. However, when the convergence frequency of the PLL circuit is high, the input voltage of the PLL circuit is temporarily increased to the maximum voltage by using the constant current source. Thereafter, the input voltage is gradually dropped from the maximum voltage so as to be converged by using the constant current source.

Claims25

Dependent claims

A PLL circuit comprising:

a phase comparator with current mode output;
a low-pass filter;
and
a VCO,
wherein in the case where a convergence frequency of the PLL circuit is lower than a setting frequency, the PLL circuit converges the convergence frequency by a PLL feedback loop from an input voltage lower than a first convergence voltage corresponding to the convergence frequency to the first convergence voltage, and
wherein in the case where the convergence frequency of the PLL circuit is higher than the setting frequency, the PLL circuit converges the convergence frequency by the PLL feedback loop from an input voltage higher than a second convergence voltage to the second convergence voltage.

3 more elements

A PLL circuit comprising:

a phase comparator with current mode output, for outputting a signal proportional to a phase difference between a first input signal modulated in its frequency and a second input signal;
a low-pass filter connected to an output terminal of the phase comparator with current mode output;
a VCO connected to an output terminal of the low-pass filter;
a mixer connected to an output terminal of the VCO and converting an output frequency of the VCO so as to output said second input signal;
first to third constant current sources connected to the output terminal of the phase comparator with current mode output;
a switch connected between the phase comparator with current mode output and a reference voltage;
and
control means for controlling an on-off of the first to third constant current sources and controlling a short-circuit and open of the switch.

5 more elements

A PLL circuit comprising:

a phase comparator with current mode output, for outputting a signal proportional to a phase difference between a first input signal modulated in its frequency and a second input signal;
a low-pass filter connected to an output terminal of the phase comparator with current mode output;
a VCO connected to an output terminal of the low-pass filter;
a mixer connected to an output terminal of the VCO and converting an output frequency of the VCO so as to output said second input signal;
first and second constant current sources connected to the output terminal of the phase comparator with current mode output;
a first switch connected between the phase comparator with current mode output and a first reference voltage;
a second switch connected between the phase comparator with current mode output and a second reference voltage;
and
control means for controlling an on-off of the first and second constant current sources and controlling a short-circuit and open of the first and second switches.

6 more elements

A PLL circuit comprising:

a phase comparator with current mode output for outputting a signal proportional to a phase difference between a first input signal modulated in its frequency and a second input signal;
a low-pass filter connected to an output terminal of the phase comparator with current mode output;
a VCO connected to an output terminal of the low-pass filter;
a mixer connected to an output terminal of the VCO and converting an output frequency of the VCO so as to output said second input signal;
a variable current source and a constant current source connected to the output terminal of the phase comparator with current mode output;
a switch connected between the phase comparator with current mode output and a first reference voltage;
and
control means for controlling an on-off of the variable current source, an output current value, an on-off of the constant current source, and controlling a short-circuit and open of the switch.

5 more elements

Dependencies are inferred from the claim text.

PLL circuit and wireless mobile station with that PLL circuit

Life of this patent

PLL circuit and wireless mobile station with that PLL circuit

Life of this patent

Abstract

Claims25