Configurable analog signal processor

An apparatus comprising a programmable analog circuit, the programmable analog circuit comprising:

• an analog input node configured to receive an analog input signal;
• a plurality of controlled current sources, wherein each controlled current source has an output current that is controlled by the analog input signal;
• a plurality of current-steering switches, wherein each current-steering switch has at least a first switch node and a second switch node, wherein each current-steering switch is paired with a corresponding controlled current source of the plurality of controlled current sources so that each controlled current source output is coupled to a respective first switch node, wherein each current-steering switch is configured to selectively enable or disable conduction between the first switch node and the second switch node based at least partly on a state of a respective a digit of a digital signal;
• and
• an output transconductance amplifier (OTA) circuit having a first input coupled to second switch nodes of the plurality of current-steering switches;
• wherein the current sources of the plurality of controlled current sources are binary weighted such that successive current sources differ in output current by a factor of two, wherein the digits of the digital signal comprise bits, wherein the bit of the digital signal controlling a particular current-steering switch of the plurality of current-steering switches matches the binary weighting of the paired controlled current source.

A method of providing a programmable analog circuit, the method comprising:

• receiving an analog input signal at an analog input node;
• providing a plurality of controlled currents, wherein each controlled current is controlled by the analog input signal;
• selectively switching the controlled currents based at least partly on states of digits of a digital signal;
• and
• summing the selectively switched controlled currents at an input node of an output transconductance amplifier (OTA) circuit;
• wherein the OTA circuit further comprises an integration capacitor, integration reset switch, sampling switch, and holding capacitor, wherein the OTA circuit has at least a linear gain mode, an integration mode, and a sample-and-hold mode.

A method of providing a programmable analog circuit, the method comprising:

• receiving an analog input signal at an analog input node;
• providing a plurality of controlled currents, wherein each controlled current is controlled by the analog input signal;
• selectively switching the controlled currents based at least partly on states of digits of a digital signal;
• and
• summing the selectively switched controlled currents at an input node of an output transconductance amplifier (OTA) circuit;
• wherein the plurality of controlled currents are binary weighted such that successive currents differ by a factor of two, wherein the digits of the digital signal comprise bits, wherein the bit of the digital signal controlling switching of a particular controlled current matches the binary weighting of the particular controlled current.

A method of providing a programmable analog circuit, the method comprising:

• receiving an analog input signal at an analog input node;
• providing a plurality of controlled currents, wherein each controlled current is controlled by the analog input signal;
• selectively switching the controlled currents based at least partly on states of digits of a digital signal;
• summing the selectively switched controlled currents at an input node of an output transconductance amplifier (OTA) circuit;
• and
• computing an N-point inverse Fourier Transform of frequency bin data in an analog manner, the method further comprising:
• operating a plurality of output transconductance amplifiers (OTAs) in linear gain mode;
• providing frequency bin data as inputs to multiple corresponding analog input nodes;
• providing a sine wave or a cosine wave of the frequency corresponding to the frequency bin as the digital signal;
• and
• summing outputs of OTAs in a node to form an output signal.

A method of providing a programmable analog circuit, the method comprising:

• receiving an analog input signal at an analog input node;
• providing a plurality of controlled currents, wherein each controlled current is controlled by the analog input signal;
• selectively switching the controlled currents based at least partly on states of digits of a digital signal;
• summing the selectively switched controlled currents at an input node of an output transconductance amplifier (OTA) circuit;
• and
• computing an N-point Fourier Transform of an analog signal in an analog manner, the method further comprising:
• operating a plurality of output transconductance amplifiers (OTAs) in an integration mode;
• providing the analog signal to analog input nodes;
• and
• providing a sine wave or a cosine wave of the frequency corresponding to a frequency bin as the digital signal for computation of the frequency bin.

An apparatus for providing a programmable analog circuit, the apparatus comprising:

• an analog input node configured to receive an analog input signal;
• means for providing a plurality of controlled currents, wherein each controlled current is controlled by the analog input signal;
• means for selectively switching the controlled currents based at least partly on states of digits of a digital signal;
• means for summing the selectively switched controlled currents;
• and
• an output transconductance amplifier (OTA) circuit having an input coupled to the selectively switched controlled currents;
• wherein the plurality of controlled currents are binary weighted such that successive currents differ by a factor of two, wherein the digits of the digital signal comprise bits, wherein the bit of the digital signal controlling switching of a particular controlled current matches the binary weighting of the particular controlled current.