Seiko Epson Corporation

Sekio Epson Corporation

Jeremy Scuteri

Gregory A Blum

Circuits and methods and for dividing a frequency of an input signal by an integer divider value. The circuit generally comprises (a) a first frequency divider, including a first plurality of serially connected delay elements receiving the input signal and a first configurable feedback network, (b) a second frequency divider, including a second plurality of serially connected delay elements receiving an inverse of the input signal and a second configurable feedback network (c) configurable logic configured to select and/or combine outputs of the first and second frequency dividers and to produce a frequency divided output signal, and (d) a programmable circuit configured to selectably configure the first and second configurable feedback networks and the configurable logic. The present invention advantageously provides for a frequency divider structure that can be easily programmed to provide any integer divide ratio with a 50% duty cycle.

Circuits and methods for programmable integer clock division with 50% duty cycle

A method, algorithm, architecture, circuits, and/or systems for low noise amplification are disclosed. In one embodiment, an amplifier can include an input stage, including a first differential input configured to receive a differential signal, a first current source coupled to the first differential input, a first current load receiving a first bias voltage and coupling the input stage to a first power supply, and a first pair of common mode feedback transistors, coupled to an output of the first current load and configured to limit a current to the first current source. The input stage provides an amplified signal to an additional stage having a structure similar to the input stage, configured to further amplify the amplified signal.

Differential low noise amplifier (LNA) with common mode feedback and gain control

Circuits and methods for detecting the lock status of a phase locked loop (PLL). The circuit generally comprises (a) a controller configured to produce a control signal in response to a reference clock signal, (b) a counter configured to count pulses of an output signal of the PLL (or a periodic derivative of the output signal) in response to the control signal, and (c) a decoder configured to (i) receive a counter output in response to the control signal, and (ii) produce a lock status output based on the counter output. The method generally comprises the steps of (1) counting pulses of a PLL (or a periodic derivative thereof) in response to a reference clock signal, and (2) indicating a lock status based on the number of counted pulses. The present invention advantageously provides a circuit designer the ability to tune the range of acceptable frequencies by choosing an appropriate reference frequency and adjusting the decoder to produce a positive lock status for a desired range of pulse counts.

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Highland, NY, United States of America

Jeremy Scuteri