Low-power programmable oscillator and ramp generator
AssigneeConexant Systems, Inc.
InventorsChristian Larsen, Gomathi Komanduru
Life of this patent
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Abstract
A circuit for generating a signal comprising a first transistor having a drain, a gate and a source. A second transistor having a drain, a source and a gate coupled to the gate of the first transistor to form a current mirror. A current source coupled to the source of the first transistor. A diode-connected transistor having a drain coupled to the source of the second transistor, a source and a gate that forms an output. A variable resistor having a first terminal coupled to the source of diode-connected transistor and a second terminal. A capacitor coupled to the second terminal of the variable resistor.
Claims19
A generating a signal comprising:
- a first transistor having a drain, a gate and a source;
- a second transistor having a drain, a source and a oate coupled to the gate of the first transistor to form a current mirror;
- a current source coupled to the source of the first transistor;
- a diode-connected transistor having a drain coupled to the source of the second transistor, a source and a gate that forms a ramp signal output;
- a variable resistor having a first terminal coupled to the source of diode-connected transistor and a second terminal;
- and
- a capacitor coupled to the second terminal of the variable resistor.
A method for generating a signal comprising:
- applying a current to a capacitor;
- comparing a voltage drop across the capacitor with a reference voltage;
- discharging the capacitor when the voltage drop across the capacitor equals the reference voltage;
- generating a ramp voltage output using the voltage drop across the capacitor;
- and
- generating a clock output using the voltage drop across the capacitor.
A programmable circuit for generating signals comprising:
- a relaxation oscillator receiving frequency control data and generating a clock signal having a frequency as a function of the frequency control data;
- and
- a programmable ramp signal generator coupled to the relaxation oscillator receiving ramp signal current data and generating a ramp signal having a current range as a function of the ramp signal current data.
Dependencies are inferred from the claim text.