5results about How to "Increase output impedance" patented technology

The invention provides a broadband gain positive slope amplitude-phase control multifunctional chip for a T / R assembly, which relates to the technical field of radio frequency integrated circuits and comprises a receiving channel, a transmitting channel, an equalization circuit, a numerical control attenuator, a numerical control phase shifter, a transmitting-receiving change-over switch module and a parallel control module. The parallel control module is used for outputting parallel control signals to the numerical control attenuator, the numerical control phase shifter and the transceiving change-over switch module; the equalization circuit is respectively connected with the receiving channel and the transmitting channel through the transmitting-receiving change-over switch module, so that a signal path of the receiving channel and a signal path of the transmitting channel multiplex the equalization circuit, the numerical control attenuator and the numerical control phase shifter; and the equalization circuit is of an on-chip integrated structure and is used for adjusting the gain of the receiving channel and the gain of the transmitting channel to present a positive slope characteristic relative to the frequency in a wide frequency band so as to compensate the frequency attenuation of an external device.

This application discloses a current calibration loop and method for current calibration of a current-controlled DAC. The current calibration loop includes: a selected reference current source and a selected current source to be calibrated; a clamping management module that clamps the output nodes of the two sources to the same fixed potential to discharge the static current of the two output nodes in different calibration modes, retaining only the current difference; an error comparison module that amplifies the current difference into a voltage difference and outputs the comparison result; a calibration control logic module that generates a calibration control signal based on the comparison result; and a calibration module that injects error compensation current into the output nodes according to the calibration control signal, so that the compensated output current of the selected current source to be calibrated is equal to the reference current provided by the selected reference current source. By discharging most of the static current and retaining only the current difference for comparison, it can respond promptly to a wide current range, significantly improve the current calibration accuracy, and adapt to various calibration modes.

The application discloses a kind of based on chopping operational amplifier circuit, the positive and negative input of operational amplifier circuit is connected to operational amplifier unit through a pair of differential pair input, then is output through output stage, operational amplifier unit includes two gain boost operational amplifier, operational amplifier circuit also includes offset voltage adjustment current circuit, chopping switch is equipped at the positive and negative input of operational amplifier circuit, the input of gain boost operational amplifier and inside, gain boost gain boost folded cascode operational amplifier with chopping technology is used, including common-mode voltage control, while improving the output impedance and gain of cascode stage, the offset, drift and 1 / f noise of itself can be eliminated, offset voltage adjustment current circuit reduces the offset voltage caused by transistor size variation in production and manufacture, output stage uses DC bias voltage control circuit, both ensure that output tube is slightly on, improve the output response speed of operational amplifier, and can be controlled at lower static power consumption level.The application realizes effective zero drift technology by independent chopping circuit.

The application claims a high-gain operational amplifier circuit for Sigma-Delta ADC. The circuit comprises a main operational amplifier, a gain-improving auxiliary operational amplifier, a bias circuit and a switched-capacitor common-mode negative feedback circuit. The main operational amplifier serves as the main body of the circuit, has a high gain and a wide bandwidth; the auxiliary operational amplifier improves the output impedance and effectively improves the DC gain of the operational amplifier; the bias circuit is used to provide appropriate DC bias voltage for the main operational amplifier and the auxiliary operational amplifier; the switched-capacitor common-mode negative feedback is used to stabilize the output common-mode voltage. The application uses the auxiliary operational amplifier to improve the gain, ensures a high input-output swing of the operational amplifier, improves the DC gain of the operational amplifier, adopts a symmetrical switched-capacitor common-mode negative feedback, ensures the bandwidth range and reduces the nonlinearity of the circuit.

The invention discloses an operational amplifier based on a floating capacitor voltage source gain bootstrap inverter, and the operational amplifier is characterized in that the operational amplifier comprises an inverter circuit which is used for carrying out the cascode gain amplification of an input signal, and then outputting the signal; the dynamic bias current source capacitance circuit is used for separating grid voltage of the inverter circuit; the zeroing capacitor circuit is used for storing the stabilized voltage and completing establishment of a working point of the operational amplifier; and the noise and the offset voltage are stored, and zero setting is completed. The suspension voltage source capacitance circuit is used for alternately charging and discharging and providing current for the operational amplifier; the gain bootstrap auxiliary operational amplifier circuit is used for providing grid voltage for the phase inverter circuit; and the switching circuit is used for regulating and controlling the working state of the operational amplifier based on an external control signal. The operational amplifier overcomes the defects that a traditional phase inverter operational amplifier is low in direct-current gain, needs an additional common-mode feedback circuit, is poor in PVT stability and the like.