A transceiver includes a first common T-coil circuit coupled to a first input-output pin of the transceiver, a termination impedance coupled to the first common T-coil circuit and configured to match an impedance of a transmission line coupled to the first common T-coil circuit, an amplifier configured to receive an input signal from the first input-output pin through the first common T-coil circuit based on a receive enable signal, and a first transmission buffer configured to transmit an output signal to the first input-output pin through the first common T-coil circuit based on a transmit enable signal.

A sum of products calculation circuit and a sum of products calculation method thereof are provided. A first input terminal of a differential amplifier is coupled to a reference voltage. A first adjustable resistance unit and a first parallel resistance unit are connected in parallel between a second input terminal of the differential amplifier and an operating voltage. A second adjustable resistance unit and a second parallel resistance unit are connected in parallel between the second input terminal of the differential amplifier and ground. A processing circuit adjusts resistance values of the first adjustable resistance unit and the second adjustable resistance unit, and calculates a sum of the products of a first input parameter and a second input parameter according to the resistance value of the second adjustable resistance unit corresponding to a situation in which an output of the differential amplifier is in transition.

A transceiver includes a first common T-coil circuit coupled to a first input-output pin of the transceiver, a termination impedance coupled to the first common T-coil circuit and configured to match an impedance of a transmission line coupled to the first common T-coil circuit, an amplifier configured to receive an input signal from the first input-output pin through the first common T-coil circuit based on a receive enable signal, and a first transmission buffer configured to transmit an output signal to the first input-output pin through the first common T-coil circuit based on a transmit enable signal.

Techniques for shielding wearable surface electromyography (sEMG) devices are described. According to some aspects, an sEMG device may comprise amplification circuitry comprising at least a first differential amplifier and at least two sEMG electrodes electrically connected to the amplification circuitry. The device may further comprise at least one auxiliary conductor not electrically connected to the amplification circuitry, wherein the at least one auxiliary conductor is configured to be electrically coupled to a wearer of the wearable device, and an electromagnetic shield surrounding the wearable device at least in part and electrically connected to the at least one auxiliary conductor.

A circuit includes a digital-to-analog conversion circuit, an amplifying circuit, a mixing circuit, and an analog-to-digital converter. The digital-to-analog conversion circuit is configured to receive and convert audio data in the digital domain and output audio data in the analog domain. The audio data includes a main-tone component. The amplifying circuit is configured to output an audio signal according to the audio data in the analog domain. The mixing circuit is configured to eliminate the main-tone component according to the audio data in the analog domain and the audio signal and to output a feedback signal. The analog-to-digital converter is configured to convert the feedback signal from the analog domain to the digital domain.

An analog discrete current mode negative feedback amplifier circuit for use with a micro-fused strain gauge is disclosed. The amplifier circuit includes a Wheatstone bridge coupled to a first power supply and a second power supply. The first power supply and the second power supply can be configured such that the periodically alternate between two voltage levels. The Wheatstone bridge can be coupled to a negative feedback amplifier circuit with common mode detection. The amplifier circuit can comprise a differential amplifier with a negative feedback configuration coupled to a common mode amplifier. In addition, the output of each of the amplifiers can be coupled to a common-mode amplifier. In a pressure sensing application, the output of the common mode amplifier serves to output the temperature while the differential amplifiers serve to output the pressure.

An example apparatus includes: a first voltage source, a first amplifier having a noninverting input adapted to be coupled to a photodiode anode and coupled to the first voltage source, an inverting input adapted to be coupled to a photodiode cathode, and an output, a first resistor coupled to the first amplifier inverting input and to the first amplifier output, a first capacitor coupled to the inverting input of the first amplifier and the first amplifier output, and a second voltage source different from the first voltage source. There is a second amplifier having a noninverting input, an inverting input and an output. The noninverting input is coupled to the output of the first amplifier, the inverting input is coupled to the second voltage source, and there is a second resistor coupled to the inverting input and the output of the second amplifier.

A signal processing circuit includes first and second resistors between an input end terminal and an output end terminal, a filter circuit that has a capacitive element that is connected to connection terminals of the first and second resistors, and an amplification circuit that is connected to the filter circuit. A cutoff frequency of the filter circuit is set by values of the first resistor and the capacitive element and a gain of the amplification circuit is set by values of the first and second resistors and a value of a feedback resistor.

A receiver front-end includes a first peaking gain stage configured to amplify a received differential pair of signals received on an input differential pair of nodes. The first peaking gain stage has a first frequency response including a first peak gain at or near a carrier frequency in a first pass band. The first peak gain occurs just prior to a first cutoff frequency. A second peaking gain stage is configured to amplify a differential pair of signals generated by the first peaking gain stage. The second peaking gain stage has a high input impedance and a second frequency response including a second peak gain at or near the carrier frequency in a second pass band. The second peak gain occurs just prior to a second cutoff frequency. The first peaking gain stage and the second peaking gain stage have a cascaded peak gain at or near the carrier frequency.

First switches are respectively connected between multiple input terminals and an inverting input of an operational amplifier. Second switches and feedback resistors are respectively sequentially series-connected between an output of the operational amplifier and nodes between the multiple input terminals and the first switches. Third switches are respectively connected between nodes between the second switches and the feedback resistors and an output terminal of an amplification circuit with an analog multiplexer.