Broadcom Corporation

Ka Lun Choi

Derek Hing Sang Tam

Provided is a circuit to convert input CMOS level signals having a predetermined duty cycle to CML level signals having a higher duty cycle. The circuit includes two differential transistor pairs connected together. The two differential pairs are constructed and arranged to use gates of the associated transistors as inputs to receive and combine a number of phase shifted CMOS input signals. The combined CMOS input signal are converted to CML level signals which are provided as circuit outputs.

Low jitter high speed CMOS to CML clock converter

A frequency dividing circuit divides a master clock frequency by a non-integer factor to provide an output clock signal whose frequency is equal to the frequency of the master clock signal divided by that non-integer factor. In one embodiment, the circuit is operative to divide the master clock frequency by 2.5.

Apparatus for frequency dividing a master clock signal by a non-integer

A charge pump circuit includes a high-swing transconductance amplifier. A high input swing transconductance is provided in a negative feedback loop of the charge pump circuit without an abrupt change in transconductance. The high-swing transconductance amplifier includes a transconductance cell and high-swing circuitry. The transconductance cell includes a current supply transistor, which provides current for transconductance while input voltages are within the operational range for the transconductance cell. When the input voltages increase so as to be outside of the operational range, the current source transistor enters into triode region of operation, and provides reduced current. The high-swing circuitry supplies the current in this case so that abrupt change in transconductance does not occur. The high-swing circuitry widens the output compliant voltage range of the charge pump circuit and hence reduces the sensitivity requirement of the VCO, Kvco, in any PLL design, in particular design for PLLs used in tuners.

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Laguna Beach, CA, United States of America

Ka Lun Choi