This disclosure relates to a cell-placeable variable-frequency digitally controlled oscillator (DCO) that consumes approximately the same current in a fast process corner as in the case of a slow process corner. By modulating the effective channel length of transistors in inverters, a fast process DCO may be slowed down to a desired frequency at nearly the same current consumption as that of a slow process DCO.

A power supply circuit having a higher power factor and decreased current crest factor. The circuit preferably comprises an input circuit for receiving an input AC voltage and rectifying this voltage and an output circuit for providing a DC output voltage. A pulse-width-modulation circuit intercouples between the input and output circuits and includes a controlled circuit adapted to pass input AC current in pulse-wide increments with the pulse-width varying in inverse proportion to the AC voltag...

A signal generator circuit having enhanced control resolution includes a variable frequency oscillator having a first control input adapted to receive a first signal and at least a second control input adapted to receive a second signal. The second signal is afforded a weight which is substantially equal to a weight of a least significant bit of the first signal. The variable frequency oscillator is operative to generate an output signal having a frequency which varies as a function of the first...

In a multifrequency generator providing tone signaling for a telephone, the common switch functions are performed by solid-state switching circuitry (12). The dc drive current level to the solid-state switching circuitry varies with the loop length of the telephone line such that saturation of switching transistors (405, 409, 410, 508 and 518) contained therein will be maintained on longer loops even with the corresponding decrease in operating current available from a central office. In the spe...

In electrical conversion systems, storage devices are selectively switched between charging and discharging states. Transistor switches are connected between the storage devices and cyclicly connect them in series. Other transistor switches and rectifiers connect the storage devices in parallel, alternating with the series connection. There is a common connection between either polarity of the input and either polarity of the output. The basic circuit is adaptable for use in various combinations...

Analog filters may be conveniently implemented in MOS technology by the use of "transconductance cells". Each cell includes stages each having a pair of current paths, with each path comprising a current source and input transistor. The gain of each stage is set by a transistor connected across the current path, with the transconductance of this transistor being controlled by its gate voltage. In the inventive technique, a transconductance cell comprising two input stages utilizes inputs to each...

An integrated circuit is disclosed that includes a biquadratic filter in which the poles and zeroes are independently adjustable. The transfer function of the filter has a pair of zeroes in the numerator and a pair of complex conjugate poles in the denominator. The integrated circuit includes a first circuit for constructing the complex conjugate poles of the filter transfer function. The first circuit has an input port for receiving an input signal and an output port at which an output current ...

An integrated circuit obtains improved ESD protection by way of a shunt protection circuit having a trigger level that exhibits a hysteresis effect with respect to voltage applied to the bondpads. The hysteresis is obtained by a string of voltage dropping transistors that produce a trigger voltage level at an intermediate node, and a shorting transistor that effectively removes at least one transistor from the string. In a typical case, a PNP bipolar transistor serves as the protective device in...

A phase-locked loop includes a variable frequency generator, a comparator and a counter. The variable frequency generator is configurable for generating an output signal having a frequency which varies based at least in part on at least first and second control signals presented thereto. The comparator is configurable for receiving a first signal and a second signal, the first signal being an input signal presented to the phase-locked loop and the second signal being representative of the output...

A phase-lock loop (PLL) circuit provides fast locking and low spurious modulation jitter through "gearshifting" control. The gearshifting PLL combines the advantages of low jitter from integer-N PLL and fast locking from fractional-N PLL. The PLL circuit includes a phase/frequency detector, a charge pump, a loop filter, and a voltage controlled oscillator (VCO). Control of the PLL circuit includes configuring the PLL circuit in two configurations, one for each phase of operation. The bandwidth o...