Abstract: An integrated circuit having two or more power domains that include load circuits in different portions of the integrated circuit is disclosed. In order to conserve power, the circuits in one of the power domains are shut down by disconnecting the power source serving that domain. The load circuits in each power domain are buffered from the load circuits in other power domains by buffer cells. The buffer cells reduce leakage currents in the power domain that is shut down, by restricting data signals from the “live” power domain from reaching the shut-down power domain, and further by providing predetermined voltage signals to the load circuits in the shut-down power domain that are selected to minimize leakage currents in the inactive load circuits. The invention further provides a corresponding method for reducing power consumption in an integrated circuit having at least two power domains separated by a buffer cell.

Abstract: A method and apparatus for communicating transmit and receive data between a digital signal processor and the baseband processing circuitry in a digital communications station such as a digital cellular telephone. The invention utilizes a transmit buffer and a receive buffer for smoothing out the flow of data. TRANSMIT BUFFER EMPTY and RECEIVE BUFFER FULL interrupts indicating the need for data to be retrieved from the transmit buffer or sent to the receive buffer, respectively, are serviced by a DMA with translation circuitry rather than the DSP. The DMA with translation circuitry intercepts the interrupts and services them by transferring data directly to or from the DSP's RAM without disturbing the DSP. The translation circuitry also arbitrates between TRANSMIT BUFFER EMPTY and RECEIVE BUFFER FULL interrupts so as to service the RECEIVE BUFFER FULL interrupts first since they have stricter timing requirements.

Abstract: A method and apparatus for generating two disparate frequency reference signals using a single phase locked loop. The circuit includes a local oscillator for generating a reference signal and a phase comparator for comparing the reference signal with a feedback signal. The output of the phase comparator is converted to a first one of the desired output frequencies by a voltage controlled oscillator. That signal is also fed to a variable frequency divider circuit under control of a &Sgr;/&Dgr; converter which generates a lower frequency signal without creating a secondary frequency tone. The lower frequency signal is the second of the output frequencies. This signal also is fed back to the second input of the phase comparator through a fixed frequency divider.

Abstract: A buffer design for use in digital signal processing for providing parallel shifting of digital data and serial output of the shifted data. The buffer includes an input shift register for receiving and shifting an input digital word, and one or more parallel shift registers connected to the input shift register for receiving and parallel shifting the shifted digital word output by the input shift register. An output shift register is connected to the parallel shift registers for shifting and serially outputting the shifted data word. The use of parallel shift registers in the inventive buffer allows for a more efficient use of chip surface area in the buffer design, thereby increasing overall chip yield and reducing chip cost.