Circuitry for performing a multiply-accumulate operation

Stochastic to consecutive edge modulation (CEM) converter circuitry comprising:

• a first counter configured to generate a first pulse width modulated signal based on a number of high bits in a first frame of a received stochastic signal;
• a second counter configured to generate a second pulse width modulated signal based on the number of high bits in a second frame of the received stochastic signal;
• and
• a selector configured to select the first pulse width modulated signal as a first frame of a CEM output signal and to invert the second pulse width modulated signal in time to generate a second frame of the CEM output signal.

Circuitry for performing a multiply-accumulate (MAC) operation, the circuitry comprising multiplexer circuitry configured to output a time division multiplexed output signal comprising portions of a plurality of unary coded multiplexer input signals selected according to a control signal received by the multiplexer circuitry from vector quantizer circuitry;

• wherein the first vector quantizer comprises a tree-based modulator;
• or
• wherein the first vector quantizer comprises:
• a plurality of integrators, each configured to receive a respective weighting signal;
• and
• a processing unit configured to, in each cycle of a computation period of the circuitry:
• determine a maximum among the outputs of the plurality of integrators;
• output a control signal to the first multiplexer to cause the first multiplexer to select an input corresponding to the weighting signal received by the integrator whose output is maximum;
• and
• reset the integrator whose output is maximum.

A device comprising circuitry for performing a multiply-accumulate (MAC) operation, the circuitry comprising:

• a first multiplexer having a plurality of inputs for receiving a plurality of unary-coded input signals representing operands of the MAC operation and an output for outputting a multiplexer output signal representing a result of the MAC operation;
• and
• a first vector quantizer configured to receive a plurality of weighting signals, each representing a proportion of a computation time period for which a respective one of the unary-coded input signals should be selected by the multiplexer and to output a first selector signal to the multiplexer to cause the multiplexer to select each of the input signals in accordance with the plurality of weighting signals;
• wherein the device comprises a portable device, a battery powered device, a mobile telephone, a tablet or laptop computer, a smart speaker, an accessory device, a headset device, smart glasses, headphones, earphones or earbuds.