110 results about "Chopper amplifier" patented technology

Chopper chopper-stabilized instrumentation and operational amplifiers having ultra low offset. The instrumentation amplifiers use current-feedback, and include, in addition to a main chopper amplifier chain, a chopper stabilized loop for correcting for the offset of the input amplifiers for the input signal and for receiving the feedback of the output voltage sense signal. Additional loops, which may include offset compensation and autozeroing loops, may be added to compensate for offsets in the chopper stabilized loop for correcting for the offset of the input amplifiers. Similar compensation is disclosed for decreasing the offset in operational amplifiers.

In a chopper amplifier circuit operable at a low voltage utilizing a switched operational amplifier, a chopper modulator chopper-modulates an input signal according to a predetermined control signal, and outputs a chopper-modulated signal. An amplifier circuit constituted by the switched operational amplifier amplifies the chopper-modulated signal outputted from the chopper modulator, and outputs an amplified chopper-modulated signal. A chopper-demodulator of the switched operational amplifier chopper-demodulates the amplified chopper-modulated signal outputted from the amplifier circuit according to the control signal, and outputs a demodulated output signal as a chopper-amplified output signal from an output terminal. A chopper modulator chopper-modulates a demodulated signal outputted from the chopper demodulator according to the control signal, and outputs a chopper-modulated signal to an input terminal of the amplifier circuit.

The present invention provides a chopper amplifier circuit capable of reducing the offset voltage of a sensor bridge and the temperature characteristic of the offset voltage. An offset adjustment voltage generating circuit is provided for generating a voltage equal to the offset voltage of the sensor bridge, and an offset temperature characteristic adjusting voltage generating circuit is provided for generating a voltage having the same temperature characteristic as the offset voltage. These output voltages are chop modulated and subtracted from the chop modulated output signal of the sensor bridge.

A chopper-stabilized amplifier (1B) having a first output (25) includes an input chopper (9) for chopping an input signal and applying it to the input of a first amplifier (2) and an output chopper (10) for chopping an output signal of the first amplifier and applying it to the input of a switched capacitor notch filter (30-1). Notch filtering of the chopped output signal is performed by coupling a first compensation capacitor (C2) between a first output (25) of the chopper-stabilized amplifier and an output (14A) of the output chopper by means of a first switch (55) in response to a filter clock (FILTERCLK) and coupling a second compensation capacitor (C3) between the first output and an input (22A) of a second amplifier (3) by means of a second switch (58) in response to the filter clock, and coupling the first compensation capacitor between the first output and the input of the second amplifier by means of a third switch (56) in response to the complement of the filter clock and coupling the second compensation capacitor between the first output and the output (14A) of the output chopper circuit (40) by means of a fourth switch (57) in response to the complement.

An RF power detector having a wide dynamic range may comprise a chopping amplifier and is configured to detect pulsed high frequency RF signals. The chopping amplifier controlled by a bias current regulator amplifies and chops an RF signal by periodically enabling and disabling the amplifier according to a system clock. The chopped high frequency RF signal feeds a Schottky diode biased to operate in the square law region for weak signals. The Schottky diode voltage is tapped and high pass filtered. The voltage drives a logarithmic and linear converter. The converter outputs are summed to produce an output voltage that is a repeatable and stable monotonically increasing function of the RF power.

A chopper-stabilized amplifier (20A) includes an amplifier (3), an input chopper (2A) having a first input (4) receiving an input signal (VIN+), an output (5) coupled to a first input of the amplifier, and a feedback resistor (9) coupled to an output (6) of the amplifier to couple a feedback signal (VFB+) to a second input of the amplifier (3). The input chopper operates in response to a chopping clock (CHOP_CLK). If the amplifier (3) is unacceptably close to a saturation condition, the chopping clock (CHOP_CLK) is disabled to reduce input leakage current (ILEAKAGE) of the chopper-stabilized amplifier.

The present invention relates to a parallel light emitting diode (“LED”) drive circuit and provides a drive circuit configured to drive a parallel array of LEDs. The drive circuit comprises: a switching control signal generator, a plurality of switches, a plurality of sampling resistors, and a plurality of chopper amplifiers. Each switch is coupled to a respective LED in the LED array. Each chopper operational amplifier configured to receive a reference voltage and a switching control signal generated by the switching control signal generator and generate an input offset voltage. Each chopper operational amplifier includes a differential amplifier including an input transistor pair and a current mirror transistor pair, of which the electrical positions can be reserved when the switching control signal is switched between a first state and a second state, wherein the offset voltage, which causes the lightness mismatching in a parallel LED circuit, can be cancelled.

A chopper-stabilized amplifier (1B) having a first output (25) includes an input chopper (9) for chopping an input signal and applying it to the input of a first amplifier (2) and an output chopper (10) for chopping an output signal of the first amplifier and applying it to the input of a switched capacitor notch filter (30-1). Notch filtering of the chopped output signal is performed by coupling a first compensation capacitor (C2) between a first output (25) of the chopper-stabilized amplifier and an output (14A) of the output chopper by means of a first switch (55) in response to a filter clock (FILTERCLK) and coupling a second compensation capacitor (C3) between the first output and an input (22A) of a second amplifier (3) by means of a second switch (58) in response to the filter clock, and coupling the first compensation capacitor between the first output and the input of the second amplifier by means of a third switch (56) in response to the complement of the filter clock and coupling the second compensation capacitor between the first output and the output (14A) of the output chopper circuit (40) by means of a fourth switch (57) in response to the complement.

Various apparatuses and methods are described where a signal is amplified using a chopper amplifier arrangement, and ripples caused by said chopper amplifier arrangement are reduced. In some cases, this reduction of ripples is performed by controlling a voltage offset of an amplifier of said chopper amplifier arrangement. In other embodiments, a detection of ripples or a chopping of the chopper amplifier arrangement is at least temporarily disabled.

A magnetic field feedback delta-sigma modulator sensor circuit, provides accurate magnetic field measurements without requiring complex additional calibration circuitry. The output of the semiconductor magnetic field sensor, which may be a Hall effect sensor, is coupled to the input of the delta-sigma modulator loop filter. The output of the quantizer of the delta-sigma modulator is magnetically coupled to the magnetic field sensor, producing a field that causes the output of the sensor to be canceled for frequencies in the band of the modulator loop filter. The output of the quantizer is provided to a current output digital-to-analog converter, which feeds a current loop that is inductively coupled to the sensor body. A chopper amplifier can be provided between the output of the sensor and the modulator loop filter input to reduce 1 / f noise and bias current and output terminals can be rotated to further reduce 1 / f noise and offset.