54 results about "Cmos amplifier" patented technology

An RNG circuit is connected to the parallel port of a computer. The circuit includes a flat source of white noise and a CMOS amplifier circuit compensated in the high frequency range. A low-frequency cut-off is selected to maintain high band-width yet eliminate the 1 / f amplifier noise tail. A CMOS comparator with a 10 nanosecond rise time converts the analog signal to a binary one. A shift register converts the serial signal to a 4-bit parallel one at a sample rate selected at the knee of the serial dependence curve. Two levels of XOR defect correction produce a BRS at 20 kHZ, which is converted to a 4-bit parallel word, latched and buffered. The entire circuit is powered from the data pins of the parallel port. A device driver interface in the computer operates the RNG. The randomness defects with various levels of correction and sample rates are calculated and the RNG is optimized before manufacture.

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit. A receiver front end provides programable attenuation and a programable gain low noise amplifier. LC filters integrated onto the substrate in conjunction with image reject mixers provide image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. Active filters utilize multi track spiral inductors with shields to increase circuit Q. The filters incorporate a gain stage that provides improved dynamic range through the use of cross coupled auxiliary differential pair CMOS amplifiers to cancel distortion in a main linearized differential pair amplifier. Frequency planning provides additional image rejection. Local oscillator signal generation methods on chip reduce distortion. A PLL generates needed out of band LO signals. Direct synthesis generates in band LO signals. PLL VCOs are centered automatically. A differential crystal oscillator provides a frequency reference. Differential signal transmission throughout the receiver is used. ESD protection is provided by a pad ring and ESD clamping structure. Shunts utilize a gate boosting at each pin to discharge ESD build up. An IF VGA utilizes distortion cancellation achieved with cross coupled differential pair amplifiers having their Vds dynamically modified in conjunction with current steering of the differential pairs sources.

A class AB output stage of a CMOS amplifier has a level-shifting voltage follower constituted by a level-shifting transistor and a current source. A bias circuit replicates the level-shifting voltage follower in a feedback arrangement to produce a variable bias voltage for the current source of both the main and replica level-shifters. The arrangement serves to control the output voltage of the level-shifter such that it provides the amplifier with a relatively constant quiescent current of the output stage over variations of manufacturing process, supply voltage, and temperature. The level shifting function can be facilitated by a resistive on-state of a power-down transistor between the level-shifting and load transistors.

A switched capacitor CMOS amplifier uses a first stage non-inverting CMOS amplifier driving a second stage inverting CMOS amplifier. The first stage amplifier is provided with positive feedback to substantially increase the gain of the first stage amplifier. In the described examples, the positive feedback is provided either by connecting a capacitor from the output to the input of the first stage amplifier or by connecting a shunt transistor in parallel with an input transistor and driving the transistor from the output of the first stage amplifier. The substantially increased gain resulting from the positive feedback allows the gain of the switched capacitor amplifier to be set by the ratio of the capacitance of an input capacitor to the capacitance of a feedback capacitor. The amplifier also includes switching transistors for periodically discharging the input capacitor and the feedback capacitor.

The present invention comprises switched capacitor amplifiers including positive feedback, semiconductor devices, wafers and systems incorporating same and methods for amplifying signals using positive feedback, while maintaining a stable gain and producing an improved signal-to-noise ratio. One embodiment includes a switched capacitor amplifier comprising a Complementary Metal Oxide Semiconductor (CMOS) amplifier, a feed-in switched capacitor, and a feedback switched capacitor. The feed-in switched capacitor operably couples an input signal to the non-inverting input of the CMOS amplifier. Similarly, the feedback switched capacitor operably couples the amplifier output to the non-inverting input to create a positive feedback loop. A capacitance of the feedback switched capacitor relative to a capacitance of the feed-in switched capacitor comprises a feedback proportion. This feedback proportion may be configured to maintain a stable gain of the switched capacitor amplifier and increase a signal-to-noise ratio of the switched capacitor amplifier, even with the switched capacitor amplifier configured in a positive feedback arrangement.

A logarithmic linear variable gain CMOS amplifier includes first and second differential pairs of transistors forming a differential input, with each differential pair of transistors including a common source node. A pair of diode-connected load transistors is connected to the first and second differential pairs of transistors, and a third differential pair of transistors is connected to the pair of diode-connected load transistors. The third differential pair of transistors include respective gates connected together and in parallel to gates of the first and second differential pairs of transistors. First and second current mirrors are respectively connected to the common source nodes of the first and second differential pairs of transistors for programmably injecting respective bias currents thereto, with a sum of the respective bias currents remaining constant.

The invention discloses a CMOS (Complementary Metal Oxide Semiconductor) low-temperature low-noise operational amplifier circuit. A biasing circuit part adopts a multi-stage current mirror sleeving mode, and reference current is generated by an active resistor of an MOS (Metal Oxide Semiconductor) tube comprising two connected diodes, so that the reference current of an amplifier has better temperature characteristics; an amplification part is of a differential input folded cascode structure, the open loop gain of the amplifier can be greater than 80dB by virtue of one-stage amplification, and the defect that oscillation is easily caused by a Miller compensation capacitor used by the conventional two-stage amplification at the low temperature of 77K is overcome; a large tube of which the width to length ratio is greater than 100 is adopted for differential input, the noise performance of a CMOS amplifier is improved favorably, and a differential operational amplifier can normally work at the normal temperature and the low temperature of 77K, can be used as a standard amplifier module designed for a low-temperature CMOS circuit, can be applied to a photovoltaic infrared detector circuit, and can also be applied to a long-wave infrared optical guide detector circuit.

An apparatus and method of reducing a flicker noise of a CMOS amplifier is provided. In the CMOS amplifier, a load circuit is connected to a signal input circuit which includes two pairs of MOSFETs which simultaneously receive differential signals. In this instance, a first MOSFET included in a switch-bias circuit is connected to one pair of MOSFETs which receive the differential signals and functions as a current source in the case of activation of a clock signal Ø1. A second MOSFET included in the switch-bias circuit is connected to another pair of MOSFETs which receive the differential signals and functions as a current source in the case of activation of a clock signal Ø2.