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US 2013/0300476 A1Published application
Low noise and low power voltage controlled oscillators
AssigneeTagArray, Inc.
InventorMohammad Ardehali
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Abstract
LC tank and ring-based VCOs are disclosed that each include a differential pair of transistors for steering a tail current generated by a current source responsive to a bias voltage. A biasing circuit generates the bias voltage such that a transconductance for the transistors in the differential pairs is inversely proportional to a resistance.
Claims20
An LC tank voltage controlled oscillator (VCO) having an output signal having a frequency responsive to a tuning signal, comprising:
- a first inductor and a second inductor, each inductor having a parallel equivalent resistance;
- a differential pair of transistors configured to steer a tail current from a current source transistor, a first transistor in the differential pair coupled to a power supply node through the first inductor and a second transistor in the differential pair coupled to the power supply node through the second inductor;
- and
- a biasing circuit configured to generate a bias voltage for the current source transistor such that a transconductance for the first and second transistors is proportional to the inverse of the parallel equivalent resistance.
1 more element
A ring-based voltage-controlled oscillator (VCO), comprising:
- A plurality of differential inverters coupled to form a loop, each differential inverter having a differential pair of transistors configured to steer a tail current from a current source transistor, the current source transistor sourcing the tail current responsive to a bias voltage, wherein a first transistor in the differential pair couples to a power source through a first voltage-controlled resistor and a second transistor in the differential pair couples to the power source through a second voltage-controlled resistor;
- and
- a biasing circuit configured to generate the bias voltage such that a transconductance for each of the transistors in the differential pair is inversely proportional to a resistance for each of the voltage-controlled resistors.
A phase-locked-loop (PLL), comprising:
- a phase detector configured to compare the phase between a divided signal and an input signal to provide a phase detector output signal;
- a loop filter configured to filter the phase detector output signal to provide a tuning signal;
- and
- a voltage-controlled oscillator (VCO) including a plurality of inverters coupled to form a loop, each differential inverter having a differential pair of transistors configured to steer a tail current from a current source transistor, the current source transistor sourcing the tail current responsive to a bias voltage, the VCO including a plurality of voltage-controlled resistors;
- and a biasing circuit configured to generate the bias voltage such that a transconductance for the transistors in the differential pairs is inversely proportional to a resistance for each of the voltage-controlled resistors.
2 more elements
Dependencies are inferred from the claim text.