Abstract: Electronic devices and accessories such as headsets are provided. An accessory may include speakers and active noise cancellation circuitry. Microphones may be used to pick up ambient noise signals for implementing noise cancellation for the speakers. The accessory may also include a voice microphone and an ambient noise microphone that picks up ambient noise signals for implementing noise cancellation for the voice microphone. A user input interface may gather user input. Ultrasonic tone generators may transmit data between the device and accessory. The electronic device and accessory may be connected to each other by audio connectors. Hybrid circuits that each include a summer and a transconductance amplifier may be selectively switched into or out of use. When switched into use, paths between the device and accessory can support bidirectional communications such as communications involving the simultaneous flow of analog audio and microphone signals in opposite directions.

Abstract: Integrated circuits such as programmable logic device integrated circuits are provided that have configuration random-access memory elements. The configuration random-access memory elements are loaded with configuration data to customize programmable logic on the integrated circuits. Each memory element has a capacitor that stores data for that memory element. A pair of cross-coupled inverters are connected to the capacitor. The inverters ensure that the memory elements produce output control signals with voltages than range from one power supply rail to another. Each configuration random-access memory element may have a clear transistor. The capacitor may be formed in a dielectric layer that lies above the transistors of the inverters, the address transistor, and the clear transistor. The inverters may be powered with an elevated power supply voltage.