Abstract: An output circuit is disclosed in which the signals to instruct the output devices to conduct or to non-conduct are coupled to the devices through optical signals. The effects of undesired parasitic signals which distort the desired signal are compensated for by capacitors in the circuit. The speed of operation for the circuit is substantially higher than can be achieved using phototransistor detection methods.

Abstract: A MOSFET output driver circuit is protected from overstress caused by commutating currents. The MOSFETs are protected by employing a gate control circuit and a small inductor in series with the sources of the MOSFETs. The circuit limits the rate of change of current that reverse biases a MOSFET's drain-source diode. The circuit is applicable to totem-pole and bridge configurations.

Abstract: A variable gain transconductance amplifier wherein complimentary input followers are used in conjunction with the multiplier to provide a high input impedance. A pair of multiplier input devices are embedded in the input followers to reduce the supply voltage used by the multiplier and to improve signal handling capability while reducing the supply voltage required. Further, these variable gain transconductance amplifiers are used in active filters to provide adjustment of the bandwidth without affecting the center frequency.

Abstract: A predistortion network preceding a continuous-time active MOSFET-C lowpass filter cancels the inherent distortion of the filter over a large portion of its passband. The lowpass filter has resistive feedback and input devices whose ratio controls its transfer function at DC and low frequencies. The predistortion network has resistive feedback and input devices that control its transfer function and that match the input and feedback devices, respectively, of the active filter. Cancellation of distortion results in low distortion operation for signals in the frequency range from DC to a substantial fraction of the passband. As the filter response rolls off at higher frequencies, imperfect cancellation results in distortion performance similar to that without predistortion. The invention reduces large signal distortion of active MOSFET-C filters, which enhances their use in monolithic system with switched capacitor circuits.

Abstract: A current-saving CMOS signal input buffer is provided, having at least two CMOS output transistors (each having an input) connected in complementary fashion with a common output taken therebetween, complementary current mirrors coupled to the output transistor inputs, an input signal capacitively coupled to at least one of the output transistor inputs, a reference impedance coupled between the complementary current mirrors, and isolation impedances coupled between the complementary current mirrors and the output transistor inputs.

Abstract: A detector is disclosed for receiving an AC signal and for generating a DC output signal indicative of the level of the input signal. The detector includes an amplifier receiving the input signal and a first transistor stage which responds to the amplifier output by developing increasing or decreasing levels of current, depending on the polarity of the amplifier's output. Second and third transistors sense those increasing and decreasing current levels for developing two intermediate currents of the same polarity. The intermediate current are coupled to a load across which a fully rectified output signal is developed.

Abstract: An integratable amplifier circuit is provided including a current generator section, a digital control section and a variable gain amplifier section. The integratable amplifier circuit is compatible with the bipolar process and can be included on an integrated circuit, such as one performing receiver and audio functions. The current generator section produces a biasing current which is applied to a digital control section which divides the biasing current according to a binary input signal to produce a control current equal to a predetermined fraction of the biasing current, corresponding to a predetermined logarithmic attenuation. The control current is applied to a control input of the variable gain amplifier section to vary the gain thereof in logarithmic steps.

Abstract: A current mirror circuit comprising a first current mirror circuit with a first error correction transistor connected between the base and collector of the first transistor of the first current mirror; a second error correction transistor connected to the first error correction transistor and a second current mirror circuit connected to an input current source and the base of the second error correction transistor. The second error correction transistor samples the signal from the collector of first error correction transistor and feeds its base current, which is almost equivalent to the base current of the first error correction transistor, to the input of the second current mirror circuit. The second current mirror circuit combines the input current source current with the base current of the second error correction transistor and generates a current which is fed to the collector of the first transistor of the first current mirror circuit.

Abstract: An integratable amplifier circuit with logarithmic electronic gain control capability. The circuit is suitable for audio applications and permit logarithmic control of volume with an external potentiometer without need to send the audio signal through control lines. In addition, the temperature coefficient of the gain is maintained at a very low level over a wide gain range.

Abstract: An analog integrated filter circuit includes a capacitance multiplier combined with a DC bias controlled current circuit designed to render the filter circuit insensitive to changes in the parameter values of the components caused by process variations or a temperature change therein. The capacitance multiplier circuit includes grounded or ungrounded capacitance multipliers in different combinations operatively coupled to the DC bias controlled current circuit so that the capacitance multiplier circuit can be used to construct a predictable low pass, bandpass or high pass filter circuit with frequency characteristics that do not vary over temperature.