A filter circuit includes a filter and a current mode programmable gain amplifier, where the filter circuit is configured to filter an input signal to obtain an output signal. The filter is supplied with the input signal. The filter comprises at least one current extraction element configured to extract a first output current signal. The current mode programmable gain amplifier is configured to receive and amplify the first output current signal to obtain an amplified current signal. The output signal is derived from the amplified current signal.

A tunable filter is provided. The tunable filter includes: a filter input; a filter output; at least one feedback loop coupled between the filter output and the filter input, where the at least one feedback loop includes at least one tunable feedback capacitance which is configured to tune a cut-off frequency of the tunable filter; and an active element, coupled between the filter input and the filter output and configured to drive the at least one tunable feedback capacitance, the active element having a transfer function with a primary pole and at least one secondary pole, where the active element includes a first stabilization element that is coupled to a first internal node of the active element.

A programmable resistor can provide discrete logarithmic (linear-in-dB) gain control. It can include multiple like programmable resistor subnetworks or cells, such as can be connected in parallel, such as according to a decoding scheme. The subnetworks can be configured to cover a subrange such as [0 dB, 6 dB) relative to the maximum resistance value. Coarse increments of 6 dB can be further added to this range by successively doubling the number of subnetworks that are connected in parallel. An additional decoder help ensure a linear control curve, free of dead zones or other nonlinearities. The programmable resistor can be suitable for use in such circuits as programmable-gain amplifiers, filters, or more complex networks, such as where the resistance can be programmed as a function of a digital code. An example including a tuning circuit for a variable gain active filter is described.

A circuit comprises a Sallen-Key filter, which includes a source follower that implements a unity-gain amplifier; and a programmable-gain amplifier coupled to the Sallen-Key filter. The circuit enables programmable gain via adjustment to a current mirror copying ratio in the programmable-gain amplifier, which decouples the bandwidth of the circuit from its gain settings. The programmable-gain amplifier can comprise a differential voltage-to-current converter, a current mirror pair, and programmable output gain stages. The Sallen-Key filter and at least one branch in the programmable-gain amplifier can comprise transistors arranged in identical circuit configurations.

We disclose transconductor-capacitor classical dynamical systems that emulate quantum dynamical systems and quantum-inspired systems by composing them with 1) a real capacitor, whose value exactly emulates the value of the quantum constant termed a Planck capacitor; 2) a quantum admittance element, which has no classical equivalent, but which can be emulated by approximately 18 transistors of a coupled transconductor system; 3) an emulated quantum transadmittance element that can couple emulated quantum admittances to each other; and 4) an emulated quantum transadmittance mixer element that can couple quantum admittances to each other under the control of an input. We describe how these parts may be composed together to emulate arbitrary two-state and discrete-state quantum or quantum-inspired systems including stochastics, state preparation, probability computations, state amplification, state attenuation, control, dynamics, and loss compensation.

We disclose transconductor-capacitor classical dynamical systems that emulate quantum dynamical systems and quantum-inspired systems by composing them with 1) capacitors that represent termed Planck capacitors; 2) a quantum admittance element, which can be emulated efficiently via coupled transconductors; 3) an emulated quantum transadmittance element that can couple emulated quantum admittances to each other; and 4) an emulated quantum transadmittance mixer element that can couple emulated quantum admittances to each other under the control of an input. We describe a Quantum Cochlea, a biologically-inspired quantum traveling-wave system with coupled emulated quantum two-state systems for efficient spectrum analysis that uses all of these parts. We show how emulated quantum transdmittance mixers can help represent an exponential number of quantum superposition states in the spectral domain with linear classical resources, even if they are not all simultaneously accessible as in actual quantum systems, and how the quantum cochlea is a very efficient spectrum analyzer for non-destructive readout of these spectral-domain signals.

A band pass filter circuit includes an amplifier circuit having a first input terminal to receive a first analog signal; a second input terminal to receive a second analog signal; first and second output terminals; capacitors; and switches. In a first switching mode, the switches are controlled so that the amplifier circuit and a first group of the capacitors connected between the input and output terminals operate as a first band pass filter filtering the first and second analog signals in a differential mode. In a second switching mode, the switches are controlled so that the amplifier circuit and second and third groups of the capacitors form second band pass filters filtering each of the first and second analog signals in a single-ended mode.

A band pass filter circuit includes an amplifier circuit having a first input terminal to receive a first analog signal; a second input terminal to receive a second analog signal; first and second output terminals; capacitors; and switches. In a first switching mode, the switches are controlled so that the amplifier circuit and a first group of the capacitors connected between the input and output terminals operate as a first band pass filter filtering the first and second analog signals in a differential mode. In a second switching mode, the switches are controlled so that the amplifier circuit and second and third groups of the capacitors form second band pass filters filtering each of the first and second analog signals in a single-ended mode.

A calibration method and a tuning method for an on-chip differential active RC filter are provided. The calibration method comprises: obtaining zero-crossing time of a differential signal outputted by a single-pole point real number filter by analyzing the single-pole point real number filter; setting a reference clock period according to the relationship between the zero-crossing time and the bandwidth of the single-pole point real number filter, and setting a calibration working time sequence according to the reference clock period; and scanning an RC configuration of an RC array according to the calibration working time sequence to realize calibration of the RC array.

A calibration method and a tuning method for an on-chip differential active RC filter are provided. The calibration method comprises: obtaining zero-crossing time of a differential signal outputted by a single-pole point real number filter by analyzing the single-pole point real number filter; setting a reference clock period according to the relationship between the zero-crossing time and the bandwidth of the single-pole point real number filter, and setting a calibration working time sequence according to the reference clock period; and scanning an RC configuration of an RC array according to the calibration working time sequence to realize calibration of the RC array.