摘要:
An RC calibration circuit, which utilizes a resistor and a variable capacitor connected in parallel, reduces power consumption and increases the accuracy of the calibration by comparing the voltage on the resistor to the voltage on the capacitor after a predetermined time has expired since the capacitor began charging up. The result of the comparison, which indicates whether the voltage on the resistor is greater than the voltage on the capacitor, is then used to adjust the capacitance of the capacitor to servo the RC time constant to a predetermined value.
摘要:
A line driver outputs a pair of transmit signals TX+ and TX− that have substantially reduced output level variations due to variations in process, voltage, and temperature. The reduced output level variations are provided by varying the magnitude of the current that sets up the voltages of the transmit signals in a manner that offsets variations in the power supply voltage, temperature, and process, and by limiting variations of the bandgap current source to process and temperature only.
摘要:
An operational amplifier circuit with improved feedback factor is provided that includes an input impedance, an operational amplifier, and a current conveyor. The input impedance is operable to receive an input signal. The operational amplifier comprises an inverting input node, a non-inverting input node, and an output node. The operational amplifier is operable to generate an output signal at the output node based on the input signal. The current conveyor is coupled between the input impedance and the inverting input node of the operational amplifier. The current conveyor is operable to provide a low impedance to the input impedance and a high impedance to the operational amplifier.
摘要:
A band-gap reference circuit with averaged current mirror offsets is provided that includes a differential amplifier circuit, a low current transistor circuit, a high current transistor circuit, and a configuration circuit. The differential amplifier circuit includes a first input node operable to receive a first input signal, a second input node operable to receive a second input signal, and an output node operable to generate an output signal based on the input signal difference. The low current transistor circuit is coupled to the differential amplifier circuit and is operable to receive the output signal and to generate the first input signal based on the output signal. The high current transistor circuit is coupled to the differential amplifier circuit and is operable to receive the output signal and to generate the second input signal based on the output signal. The configuration circuit is coupled to the low current transistor circuit and to the high current transistor circuit. The configuration circuit is operable to configure the band-gap reference circuit for a plurality of states by switching a plurality of components between the low current transistor circuit and the high current transistor circuit at specified intervals.
摘要:
There is disclosed high-speed current-mirror circuitry and methods of operating the same. An exemplary impedance-peaking current mirror comprises a N-channel drive transistor and a N-channel mirror transistor. The N-channel drive transistor has a source coupled to ground, a drain coupled to a current source and a gate coupled to the drain via a series connection of a resistor and an inductor. The N-channel mirror transistor has a source coupled to ground, a gate coupled to the drain of the N-channel drive transistor, and a drain coupled to a positive power supply via an impedance load.
摘要:
A low voltage differential signal (LVDS) driver circuit with reduced power consumption. A pre-driver stage, implemented as a differential current mode amplifier, is driven by the differential input signal and provides a corresponding differential drive signal, which drives the output stage, implemented as a differential voltage mode amplifier, which, in turn, provides the differential output signal for the load. Total current consumption equals the load current, which is provided by the output stage, plus a much smaller current used by the pre-driver stage.
摘要:
A slow monitor diode having a bandwidth only partially overlapping a lower end of a data transmission spectrum for a data transmission laser is employed to detect and control average output power of the data transmission laser and, from peak-to-peak measurements, optical modulation amplitude. The output current from the monitor diode reaches a peak value for long runs of consecutive logical 1's or 0's. Using peak detectors with a long decay rate, the peak-to-peak signal amplitude, directly representative of optical modulation amplitude, may be determined.
摘要:
A circuit with low noise and reduced offset that feeds an input of an opamp with a programmable feedback resistor that provides variable gain settings. Input biasing currents are varied using control bits that are also used to adjust the gain. When the input signal is small (gain at higher setting), a minimum bias current is provided to source the input voltage swing. This scheme reduces the noise and offset generated by the lower transconductance of a biasing transistor while maintaining a constant SNR and fixed offset even in the presence of relatively small input swings. Also, when the input signal is large (gain at lower setting), a maximum bias current can be provided to accommodate the relatively large input swing level. Although the overall noise and offset current are increased for large input swings, the overall SNR and offset is maintained for relatively lower input swings.
摘要:
A low voltage differential signal (LVDS) driver circuit with reduced power consumption. A pre-driver stage, implemented as a differential current mode amplifier, is driven by the differential input signal and provides a corresponding differential drive signal, which drives the output stage, implemented as a differential voltage mode amplifier, which, in turn, provides the differential output signal for the load. Total current consumption equals the load current, which is provided by the output stage, plus a much smaller current used by the pre-driver stage.