Ams Ag

Jia Sheng Chen

Gregor Schatzberger

A phase-locked loop circuitry () having low variation transconductance design comprises a voltage controlled oscillator structure () to provide an output signal (Fosc) having an oscillation frequency. The voltage controlled oscillator structure () comprises a voltage-to-current converter circuit () and a current controlled oscillator circuit (). The voltage-to-current converter circuit is designed with a low variation transconductance. The voltage-controlled oscillator circuit () has a characteristic curve being independent of different PVT (processes, supply voltages and temperature) conditions to ensure that the phase-locked loop circuitry () is stable under different PVT condition.

Phase-locked loop circuitry having low variation transconductance design

A phase-locked loop circuit comprises an oscillator having a plurality of operating curves and being suitable for generating an output signal. In a calibration state the oscillator is trimmed to an operating curve for use in a normal operation state. The phase-locked loop circuit further comprises a phase/frequency detector being suitable for generating at least one error signal based on an input signal and a feedback signal generated on the basis of the output signal. The phase-locked loop circuit further comprises a loop filter being suitable for generating a loop-filter signal based on the at least one error signal, the loop-filter signal being applied to the oscillator in the normal operation state. The phase-locked loop circuit further comprises a calibration circuit being suitable for trimming the oscillator to the operating curve for use in the normal operation state on the basis of the at least one error signal.

Phase-locked loop circuit

The PLL circuit comprises a phase/frequency detector (), a loop filter (), a VCO () and a feedback loop (). The VCO can be electrically disconnected from the PLL and comprises a programmable trimming circuit () and a current-controlled oscillator (). For calibration the VCO is electrically disconnected from the loop filter and from the feedback loop, a constant reference voltage is applied to the voltage input (IN), a center frequency programming code (L) is applied to the trimming circuit, the center frequency programming code is iteratively adjusted until a desired center frequency is obtained, a gain programming code (K) is applied to the trimming circuit while the adjusted code is still applied, and the gain programming code is iteratively adjusted until a desired gain is obtained. Then the VCO is connected to the PLL, which is then ready for normal operation.

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Premstaetten, Austria

Jia Sheng Chen