Abstract: A circuit includes a digital-to-analog converter (DAC), coupled to a power supply, that provides a first current at a first output terminal of the DAC and a second current at a second output terminal of the DAC, the first current being differential to the second current; a first circuit, coupled to the first output terminal of the DAC and to the second output terminal of the DAC, that generates a first voltage and a second voltage, the first voltage being non-linear with respect to the first current and the second voltage being non-linear with respect to the second current; and an attenuator coupled to the first circuit, and responsive to the first voltage and the second voltage to attenuate an input signal of the attenuator and to generate linear attenuation characteristics in decibels with respect to the first current and the second current.

Abstract: An integrated circuit (IC) includes an input/output (I/O) circuit supporting high-speed operation and multiple I/O logic-level swings. The I/O circuit includes a first output signal chain to generate outputs with a first logic level swing, and a second output signal chain to generate outputs with a second logic level swing. The outputs of the first output signal chain and the second output signal chain are connected to a same output pad of the IC. Transistors in the first output signal chain and the second output signal chain are fabricated using corresponding gate oxide characteristics. The second output signal chain includes protection circuitry to prevent transistors in the second output signal chain from being subjected to voltage stresses beyond a safe limit. An input circuit in the I/O circuit similarly includes multiple input signal chains to enable reception of input signals of different logic-level swings from a same input pad.