Maxim Integrated Products, Inc.

North American Philips Corporation

University of California

Hewlett-Packard Company

North American Philips Corp., Signetics Div.

Robert G Meyer

Joel David Birkeland

Jeffrey Douglas Scotten

Madhu Avasarala

Joseph T Santos

An attenuation circuit uses a voltage controlled variable resistance transistor as a signal attenuator for receivers operating in the zero Hz to about 30 MHz range. The transistor functions in the linear region to linearize the transistor resistance characteristics used for signal attenuation. In an exemplary application, the attenuation circuit is used as an RF attenuator for AM radio broadcast receivers and amplifiers with automatic gain control. Multiple attenuation circuits can be coupled in parallel, each attenuation circuit having a different sized variable resistance transistor, to form sequentially activated stages that increase the range of attenuation while minimizing distortion.

Low distortion MOS attenuator

Voltage controlled variable attenuators are described that are configured to be coupled to a transmission path to furnish variable attenuation of a signal, such as a radio frequency signal. In one or more implementations, the voltage controlled variable attenuator includes at least one transistor. The transistor has an open configuration for at least substantially preventing the flow of current through the transistor, and a closed configuration for at least partially allowing the flow of current through the transistor. The variable attenuator also includes a resistive component coupled to the transistor, and configured to couple to the transmission path. The resistive component is configured to at least partially mitigate non-linear effect when the transistor transitions from the open configuration to the closed configuration. The transistor and the resistive component are configured to at least partially attenuate a signal transmitted along the transmission path when the transistor is in the closed configuration.

Voltage controlled variable attenuator

Embodiments of the present invention provide systems, devices and methods for detecting the RMS value of a signal. The RMS detector uses multiple variable-gain stages and internal gain control to generate an RMS output signal based on an arbitrary signal input. This RMS detector significantly reduces the signal swings seen on a squarer within prior art RMS detectors and reduces the detector's dependency on DC offsets at low signal levels and overload errors at high signal levels. The embodiments of the present invention also improve the accuracy of the RMS detector within large dynamic signal ranges by obviating the operation of a squarer in saturation or out of the squaring region. Accordingly, embodiments of the present invention are able to more accurately detect RMS values on a signal, operate over relatively higher signal ranges, and better function within different signal modulation schemes, particularly those with large peak-to-average ratios.

RMS detector with automatic gain control

An ESD protection device has a multi-stage RC-timed architecture to turn on quickly and sink current for a relatively long time period. For example, a high power voltage clamp and a low power voltage clamp coupled in parallel to protect internal circuitry of an integrated circuit. The high power clamp turns on during the first few microseconds of an ESD event, and sinks current for a brief period of time, during which the low power clamp turns on as well. Once the high power clamp turns off, the low power clamp continues to sink current until a safe level is reached.

ESD protection method for low-breakdown integrated circuit

A tunable electronic filter circuit is provided including an input terminal and an output terminal connected to the input terminal with a node therebetween. An inductor, a variable capacitor, and a variable resistor are connected between the node and ground. Coupled to the variable capacitor and the variable resistor is a feedback control circuit. The feedback control circuit is operable to tune the variable capacitor in order to set a predetermined frequency, or center frequency, of the electronic filter circuit. The feedback control circuit is further operable to tune the variable resistor in order to calibrate a quality factor of the electronic filter circuit. In use when an input signal is applied to the input terminal, the electronic filter circuit passes an output signal to the output terminal. Such output signal includes components of the input signal within a predetermined frequency bandwidth set by the predetermined frequency and filters out other components of the input signal. As an option, a &ldquo;slave&rdquo; tunable electronic filter circuit may be providing including a variable capacitor and a variable resistor which are also controlled by the feedback circuit. This allows the &ldquo;slave&rdquo; filter to be tuned while being used.

Enhanced LC filter with tunable Q

A very-wide-dynamic-range amplifier with very low-noise in the high-gain mode and very high-input-overload in the low-gain mode. The amplifier utilizes two parallel signal paths, one a high-gain, low-noise path and the other a low-gain, high-input-overload path. Each path includes a gain-control capability so that the gain of each path, and the contribution of the gain of each path to the overall gain of the amplifier may be smoothly varied from a very low-gain to a very high-gain. Specific embodiments including input impedance matching capabilities are disclosed.

Wide-dynamic-range variable-gain amplifier

In accordance with the teachings of this invention, a novel wide-band, DC coupled, single-ended voltage-to-current converter and gain control circuit is provided. Of importance, the circuit of this invention is designed to receive an input signal referenced to ground such that for zero input current, zero output current is provided. A replica bias circuit is used which allows the output signal to be a function of the input signal without offsets introduced by bias currents used throughout the circuit.

Wideband single-ended voltage-to-current converter and gain-control

An integrated circuit (10, 22) contains an active bypass (36) that inhibits high-frequency supply-voltage variations caused by interaction of the circuitry elements (28) with the parasitic inductances (L.sub.HE, L.sub.HP, L.sub.LP, and L.sub.LE) associated with the power supply lines (16.sub.H /24.sub.H /26.sub.H /32.sub.H and 16.sub.L /24.sub.L /26.sub.L /32.sub.L) for the circuit. The bypass centers around a transistor (Q.sub.BP) coupled between the supply lines. An activation circuit (38) provides the transistor with a control signal (V.sub.C) to activate the transistor. A sensing capacitor (C.sub.S) provides a capacitive action between the transistor control electrode and one of the supply lines.

Active bypass for inhibiting high-frequency supply voltage variations in

A wideband amplifier is configured to allow sophisticated low voltage signal processing in a low-cost, high frequency integrated circuit driver. The integrated circuit driver provides output currents to drive high voltage discrete power transistors in such a way as to achieve maximum frequency response from the low-cost discrete transistors. The discrete power transistors in turn provide an output voltage suitable for driving, for example, a CRT display. The transconductance amplifiers, video processing circuitry, current multipliers, and summers are formed in an integrated circuit device utilizing readily available processing and circuit design techniques, and a relatively small number of discrete low power components, including pull-up and pull-down transistors which are chosen to have a fairly high frequency of unity current gain (F.sub.t), yet which are readily available at a very low cost. In order to utilize such low cost pull-up and pull-down transistors, these transistors are driven either in cascode or in a unity gain current mirror configuration from separate pull-up and pull-down currents, in order to avoid the deleterious effects the input base capacitance of the transistor has on its frequency response.

Wideband class AB CRT cathode driver

A one-pin crystal oscillator 20 is designed to be used as a clock generator for digital integrated circuits. Unlike the prior art, this oscillator requires only one package pin to connect the crystal as opposed to the usual two pin requirement and, except for the crystal, can be completely fabricated on a chip so as to require no other external components.

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Berkeley, CA, United States of America

Robert G Meyer