Micrel, Incorporated

Iowa State University Research Foundation, Inc.

Jonathan Scott McCalmont

Mihail Sigalas

William Andrew Burkland

Kai-Ming Ho

Gary L Tuttle

Sandhya Gupta

A common-mode feedback circuit is provided for fully-differential operational amplifier stages of a multistage amplifier. A first stage of the circuit establishes a substantially constant current output level for a feedback generating stage of the circuit. An exemplary embodiment using MOSFET devices illustrates using a diode-connected MOSFET and mirror MOSFET first stage and a generating the current for a common-source connected MOSFET second stage connected to the respective outputs for said fully-differential operational amplifier. An output stage of the circuit provides feedback voltage at a first level when inputs to said fully-differential operational amplifier are in equilibrium and at a second level for balancing said fully-differential operational amplifier when inputs to said fully-differential operational amplifier are not in equilibrium.

Common-mode feedback circuit

A reference circuit provides a reference electrical characteristic such as a current or voltage using a low-threshold field effect transistor (FET) for improved start-up operation. The use of a low-threshold FET eliminates a stable operating point from occurring at zero current allowing the elimination of additional startup circuitry thereby providing power and space savings, particularly in analog CMOS circuitry. Additionally, the use of a low-threshold FET allows a lower voltage requirement from the power supply providing additional power savings.

Self-starting reference circuit

A filter is described for digitally processing an analog input signal with analog feedback. In one example, the filter uses a topology similar to a second order universal filter block and includes a signal combiner for producing an analog output signal based upon an analog input signal and one or more analog feedback signals. An analog to digital converter processes the analog output signal into a digital data stream which is digitally processed to produce one or more digital output signals which are converted to one or more analog feedback signals. The digital processing can include a bandpass transfer function and a lowpass transfer function. The filter may be implemented in mixed-signal CMOS using standard CMOS processing techniques.

Filter for digitally processing an analog input signal with analog feedback

A circuit receives a first supply voltage on a first terminal where the first supply voltage is used to supply circuitry within the circuit. The circuit includes an input terminal receiving a first signal and an input circuit coupled to the input terminal. The first signal has a logical high value at a second voltage and a logical low value at a third voltage. The second voltage is used to establish a switching threshold of at least some of the input and output signals of the circuit. The input circuit provides a reset signal to circuitry within the circuit causing the circuitry to reset. The reset signal is asserted when the first signal on the input terminal has a logical low value and the third voltage comprises a voltage below a predetermined trigger threshold of the input circuit.

Input terminal with combined logic threshold and reset function

A circuit is provided to transfer data between a first data bus section operating on a first supply voltage and a second data bus section operating on a second, different supply voltage. The circuit includes a first circuit path and a second circuit path each coupled to receive a data signal from one data bus section and to drive the other data bus section. Each of the first and second circuit paths includes a delay circuit, a flip flop, a logic circuit providing an AND function and an output driver circuit. In operation, when the data signal received on one of the first and second data bus sections has a first logical value, an output driver signal of the respective circuit path is asserted and the output driver circuit drives the other data bus section to the first logical value in response to the output driver signal.

Bi-directional bus level translator

A method of manufacturing a flexible metallic photonic band gap structure operable in the infrared region, comprises the steps of spinning on a first layer of dielectric on a GaAs substrate, imidizing this first layer of dielectric, forming a first metal pattern on this first layer of dielectric, spinning on and imidizing a second layer of dielectric, and then removing the GaAs substrate. This method results in a flexible metallic photonic band gap structure operable with various filter characteristics in the infrared region. This method may be used to construct multi-layer flexible metallic photonic band gap structures. Metal grid defects and dielectric separation layer thicknesses are adjusted to control filter parameters.

Growing community of inventors

Ames, IA, United States of America

Jonathan Scott McCalmont