Abstract: A microprocessor is implemented using sense amplifiers to replace CMOS logic circuits, in order to provide low voltage, high frequency switching. The input node of the sense amplifier is maintained at a voltage just above or just below their trip-point of one inverter in order to obtain high-speed switching. Bench mark tests have shown that a microprocessor operating at 2.7 volts may obtain a frequency of 20 MHz and while the same microprocessor may operate at 5.5 volts and 40 MHz.

Abstract: A method and apparatus for shifting data in an array of storage elements (22-37) in a data processing system (10). In one form, the present invention uses multiplexer (MUX) logic (38) and Shift Control signals to selectively couple storage elements (22-37) to latches (39-42). In this manner, data values can be serially scanned into and out of the array for test purposes without requiring a duplicate set of latches. The MUX logic 38 couples one storage element (22-37) to each latch (39-42). Then MUX logic 38 decouples those storage elements (22-37). Next, MUX logic 38 couples an adjacent storage element (22-37) to each latch (39-42). In this manner, the storage elements (22-37) in one row and the latches (39-42) mimic the functionality of a shift register.

Abstract: An integrated circuit, such as a microprocessor or math coprocessor, having a clock generator circuit for generating a high frequency internal clock signal based on an external input signal is disclosed. A clock generator circuit comprises circuitry for detecting an active edge of an input signal, circuitry for generating a plurality of clock edges responsive to the detection of the clock signal and circuitry for inhibiting the edge generating circuitry after generation of a predetermined number of clock edges. The factor by which the input clock signal is multiplied may be set by the circuit designer, or programmably set, without impact on the circuit design. Hence, a single circuit may be used to generate clocks of various frequencies. Further, the duty cycle of the generated clock is independent of the input clock signal.

Abstract: An integrated circuit, such as a microprocessor or math co-processor, having a clock generator circuit for generating a high frequency internal clock signal based on an external input clock signal is disclosed. The clock generator circuit includes a programmable delay stage having fixed and variable portions. The fixed portion preferably includes a series of logic elements of various types (NOR, NAND, NOT, pass gates, etc.), selected to match the worst case clock phase delay and which match speed variations as a function of voltage, temperature or processing conditions. The variable portion of the delay stage selects a propagation delay by way of programmable elements (e.g., mask programmable); multiplexers may be included therein to allow selection of the delay in a test mode.

Abstract: A variable bandwidth phase-locked loop clock generator circuit is disclosed. The PLL circuit includes a phase comparator which presents pump-up and pump-down signals, indicating the polarity of the desired frequency change. The phase comparator also generates multiple level control outputs to control the rate of the frequency change. A current source includes a reference leg having a plurality of resistors which are shorted out according to the control outputs, from which a bias signal is generated. The level of the bias signal controls current sources in the output leg of the current source to control the rate of change of the voltage applied to the voltage controlled oscillator. In addition, the bias signal also controls the slew rate of an active low-pass filter according to the desired response characteristic; the output of the filter is applied to the voltage controlled oscillator for generating the output clock signal.

Abstract: A sense amplifier with an integral logic function for use in a circuit such as a tag cache portion of a microprocessor cache. In one form, the integral logic function is an exclusive-OR function. The sense amplifier senses a differential voltage developed between a differential pair of bit lines which are coupled to predetermined bit positions of a plurality of entries in a tag cache. While sensing the voltage, an exclusive-OR function is performed between the logic state of the sensed bit and a corresponding input address bit. If the input address bit matches the sensed bit, then a match signal is asserted. The value of the corresponding input address bit configures the circuit either to provide an output signal in a predetermined logic state if a true bit line signal voltage exceeds a complement bit line signal voltage, or to provide the output signal in the predetermined state if the complement bit line signal voltage exceeds the true bit line signal voltage.

Abstract: A method and apparatus in an integrated circuit having a plurality of distinct circuit modules which eliminates undesired effects of clock skewing when a common system clock is used. The same phase of the same system clock is used by both a transmitting circuit module and a receiving circuit module when data is communicated between two circuit modules. The receiving circuit module has an input portion having a first transistor clocked by the same phase of the same system clock, a latch and a second transistor. The latch and second transistor are clocked by a complement of the same phase of the system clock.