摘要:
A level shifter comprising a first driver transistor receiving an input signal. A gate-controlled transistor coupled to the first driver transistor. A second driver transistor coupled to the gate controlled transistor. An output coupled to the second driver transistor, wherein the gate-controlled transistor is for receiving a predetermined gate voltage when the output voltage exceeds a predetermined value.
摘要:
A battery assisted level shifter comprises a pull up transistor pulling up an output when a received input signal is high, a pull down transistor pulling down the output when the received input signal is low, and a battery element to provide voltage offsets. The battery element can be implemented using one or more pull-up transistors for assisting with pulling up the output. The level shifter can be used in class-D amplifiers, DC-DC power converters and interfaces between circuits having different reference voltages.
摘要:
In today's environment class-D amplifiers are used to provide an integrated solution for applications such as powered audio devices due to their advantages in power consumption and size over more traditional analog amplifiers. Due to power output requirements, the output stages of power drivers such as class-D amplifiers require a supply voltage in excess of the technologically allowed voltage for the switches in the output stage. A level shifter is used to ensure voltages supplied to the output switches do not exceed the technological limits. An ideal level shifter should provide the optimal voltage swing to output switches under all process, supply voltage and temperature (PVT) variations. The ideal level shifter should also provide fast transitions when the control signal changes from high to low and low to high.
摘要:
A capacitive voltage converter providing multiple gain modes comprising a switched capacitor array having a voltage input and a voltage output. A skip gating control coupled to the switched capacitor array and configured to control a switch resistance value of the switched capacitor array, and to control a switching sequence of the switched capacitor array. An override control coupled to the skip gating control and the switched capacitor array, the override control configured to detect transitions in a gain mode and to modify the switch resistance value of the switched capacitor array and the switching sequence of the switched capacitor array for a finite amount of time following the gain mode transition.
摘要:
Direct current (DC) offset in and audio driver can cause a constant drain on power even when there is no sound. Furthermore it can cause an audible pop when the audio driver is enabled. A scaled replica output stage can be employed to perform DC offset cancellation offline during a sampling phase. Once DC offset cancellation is achieved, the audio driver uses a full scale output stage during the operation phase.
摘要:
Presently many audio chips suffer from pop issues, which is especially serious for single ended audio drivers. An audio pop is a disturbance in the output caused by a sudden transition of chip power, particularly when a chip is powered on or powered off. Furthermore, compensation networks included in the amplifiers on audio chips for stability offer a significant path for transmitting power disturbances to the output. Hence, circuitry is developed to suppress pops in the output stages of an amplifier.
摘要:
An integrated audio codec includes a high-pass filter to prevent damage to personal computer speakers and other components. The audio codec may be compliant with HD audio standards and can operate with generic software drivers. Tuning of the high-pass filter is provided through an external pin-out where either an external capacitor or external resistors provide an ability to tune the high-pass filter. In one implementation, a tuning voltage is digitized into a tuning code used by a digital high-pass filter. In addition, multiplexers can be used to insure only the audio path leading to the speakers is filtered.
摘要:
Presently many audio chips suffer from pop issues, which is especially serious for single ended audio drivers. An audio pop is a disturbance in the output caused by a sudden transition of chip power, particularly when a chip is powered on or powered off. Furthermore, compensation networks included in the amplifiers on audio chips for stability offer a significant path for transmitting power disturbances to the output. Hence, circuitry is developed to suppress pops in the output stages of an amplifier.
摘要:
A driver controller comprising a state machine for controlling transitions between a plurality of states. An output switch for providing a low impedance path to ground during transition periods. An output stage for decoupling output signal from driver amplifier during the transition periods.
摘要:
A grounding switch is described which operates properly even in the presence of negative voltages on a signal line. The grounding switch uses isolated field effect transistors that have their substrates tied to different voltages. The isolated field effect transistor has a gate voltage and substrate voltage which can be pulled down to a negative voltage when the signal line has a negative voltage allowing the switch to remain open even with a negative voltage.