Abstract: Methods of fabricating negative-channel metal-oxide semiconductor (NMOS) devices and positive-channel metal-oxide semiconductor (PMOS) devices having complementary threshold voltages are described. Elements of lower-threshold voltage NMOS devices are formed at first locations on a substrate. Elements of higher-threshold voltage PMOS devices are formed at second locations on the substrate. Elements of higher-threshold voltage NMOS devices and elements of lower-threshold PMOS devices are formed by adding a same amount of p-type dopant at selected locations chosen from the first and second locations.

Abstract: Methods of fabricating negative-channel metal-oxide semiconductor (NMOS) devices and positive-channel metal-oxide semiconductor (PMOS) devices having complementary threshold voltages are described. Elements of lower-threshold voltage NMOS devices are formed at first locations on a substrate. Elements of higher-threshold voltage PMOS devices are formed at second locations on the substrate. Elements of higher-threshold voltage NMOS devices and elements of lower-threshold PMOS devices are formed by adding a same amount of p-type dopant at selected locations chosen from the first and second locations.

Abstract: A class AB analog inverter comprising cascoded n-channel (NMOS) and p-channel (PMOS) transistors. The inverter uses complementary devices, of which one or more may be a first transistor in cascode with a second transistor. The first and second transistors may have the same threshold voltage (VT), or may have different threshold voltages. The class AB inverter provides improved slew rate and low power capabilities for use in mixed-signal integrated circuits such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), and active filters.

Abstract: Embodiments of the present invention relate to a switched-capacitor filter which comprises a first stage which itself comprises a first switched capacitor, a second stage which itself comprises a second switched capacitor, a switched capacitive element that couples the output of the first stage to the input of the second stage, and a non-switched capacitive element coupled from the output of the second stage to the input of the first stage to provide damping of the switched-capacitor filter. Both stages are implemented as inverting analog amplifiers and the filter is especially well suited to semiconductor manufacture. The switched capacitor filter is implemented as part of a user module in a programmable system on a chip, or PSoC.

Abstract: A low offset voltage buffer which comprises a first, second, third and fourth MOS device, each comprising a gate, a source and a drain; a current source coupled to the drains of the first and second MOS devices; a current sink coupled to the sources of the third and fourth MOS devices; an input coupled to the gate of the third MOS device and an output coupled to the source of the first MOS device. The source of the first MOS device is coupled to the drain of the third MOS device and the source of the second MOS device is coupled to the drain of the fourth MOS device. The voltage buffer can also be implemented in both NMOS and PMOS devices.

Abstract: A fully differential switched-capacitor biquad low pass filter (40) includes a first stage (54), second stage (56), common-mode circuits (55, 72), and feedback transmission gates (73, 74). The first stage (54) includes a first operational amplifier (47), and the second stage (56) includes a second operational amplifier (69). Glitches, or transients, which are caused by the operational amplifiers (47, 69) operating in slew rate limit mode, are prevented from affecting the differential output signals of the filter (40) when the filter (40) is operating with a continuous time output. This is accomplished by preventing the operational amplifiers (47, 69) from operating in slew rate limit mode, or by adjusting the clock signals such that the output of the filter (40) is not coupled to an operational amplifier (47, 69) that is recovering from operation in slew rate limit mode.

Abstract: A semiconductor capacitor for use in an analog-to-digital converter includes two parallel connected capacitors with separate lower plates (44) and (46) fabricated of polycrystalline silicon and upper plates (52) and (54) also fabricated of polysilicon. The plates are separated by capacitive oxide dielectric structures (48) and (50). They are interconnected such that the lower plate (44) of one capacitor is connected to the upper plate (54) of the other capacitor and the lower plate (46) of the other capacitor is connected to the upper plate (52) of the first capacitor. With such a configuration, the odd ordered non-linearities contributing to the voltage coefficient errors are cancelled.

Abstract: A self-calibrated analog-to-digital converter with a corrected output includes an analog modulator (18) for receiving an analog input voltage and outputting a pulse train having a value proportional to the analog input voltage. The pulse train is filtered by a digital filter (20) which has the output thereof input to a calibration module (24). The calibration module (24) is controlled by a calibration control circuit (28) and is operable to correct the output to account for offset and gain errors. Prestored calibration parameters in a register (30) are utilized for this compensation. In a self-calibration mode, the control circuit (28) is operable to control a calibration multiplexer (12) to select a zero-scale input voltage on a terminal (16) and a full-scale reference voltage on a terminal (14) for input to the modulator (18).

Abstract: A chopper stabilized analog-to-digital converter includes an analog modulator (10) and a digital filter (12). The analog modulator (10) is comprised of two integrators (20) and (22). The first integrator (20) is a chopper stabilized integrator which is comprised of a chopper stabilized differential amplifier (32) and a capacitively switched input. The amplifier (32) is operable to receive a chopping frequency F.sub.CH that is one-half the sampling frequency F.sub.S and synchronized thereto. The amplifier (32) is operable to modulate the noise up to the chopping frequency F.sub.CH, which frequency is in the rejection portion of the filter response for the digital filter (12), thus rejecting 1/f noise.

Abstract: A semiconductor capacitor for use in an analog-to-digital converter includes two parallel connected capacitors with separate lower plates (44) and (46) fabricated of polycrystalline silicon and upper plates (52) and (54) also fabricated of polysilicon. The plates are separated by capacitive oxide dielectric structures (48) and (50). They are interconnected such that the lower plate (44) of one capacitor is connected to the upper plate (54) of the other capacitor and the lower plate (46) of the other capacitor is connected to the upper plate (52) of the first capacitor. With such a configuration, the odd ordered non-linearities contributing to the voltage coefficient errors are cancelled.

Abstract: A latch circuit utilizes a series-gated, emitter coupled logic structure including a current source providing a gate current substantially proportional to temperature for developing an output signal swing substantially proportional to temperature, thereby allowing the output signal swing to have a reduced magnitude at nominal temperatures. The load across which the output signal is developed includes a resistor coupled in series with a semiconductor P-N junction. Emitter areas of emitter-coupled transistor pairs within the latch circuit are mismatched for creating an offset tending to compensate changes in the voltage across the semiconductor junction within the load resulting from the switching action of the latch circuit. A bias circuit maintains the switching threshold reference voltage substantially intermediate the output signal swing.