Non-linear mapping of threshold voltages for analog/multi-level memory

An analog-to-analog converter comprising:

• an array of reference cells, the reference cells having a plurality of different threshold voltages;
• a sense circuit coupled to the array;
• an encoder coupled to the sense circuit, wherein the encoder generates a digital signal that represents a value that depends on which of the reference cells conduct when an analog input signal is applied to a set of reference cells;
• a plurality of memory cells coupled to the digital signal and having a plurality of different threshold voltages;
• a read circuit capable of reading a threshold voltage of a memory cell and generating an analog output signal that has a voltage representing the threshold voltage read, wherein the analog output signal is different than the analog input signal;
• and
• a select circuit coupled to the plurality of memory cells and the read circuit, wherein the select circuit selects which of the plurality of memory cells the read circuit reads, the selection being according to the digital signal.

A method of converting an analog input signal to an analog output signal comprising:

• converting the analog input signal to a digital signal;
• applying the digital signal to a plurality of analog/multi-level memory cells;
• and
• reading the threshold voltage of the memory cell corresponding to the digital signal, wherein the analog output signal is representative of the read threshold voltage and is different than the analog input signal.

A method of converting an analog input signal to an analog output signal, comprising:

• applying the analog input signal to a first row of memory cells;
• sensing which of the memory cells conduct when the analog input signal is applied;
• generating a digital output signal from the memory cells that conduct;
• applying the digital output signal to a second row of memory cells;
• and
• reading the threshold voltage from the memory cell in the second row that corresponds to the digital output signal, wherein the threshold voltage is representative of the analog output signal, which is different than the analog input signal.

A converter comprising:

• a first array of memory cells;
• a circuit that applies an analog input signal to control gates of memory cells in the first array;
• an encoder coupled to the first array, wherein the encoder generates a digital output signal having a value determined by which of the memory cells in the first array conduct when the analog input signal is applied;
• a read circuit coupled to read a selected one of the memory cells in the first array and generate an analog output signal representative of the threshold voltage of the memory cell read, wherein the analog output signal is different than the analog input signal;
• and
• a second array of memory cells for storing the analog output signal.

A converter comprising:

• a first array of memory cells for storing data values;
• a second array of memory cells that includes a plurality of row lines, each row line coupled to the control gates of memory cells in the row;
• a first selection circuit coupled to the row lines in the second array, the selection circuit receiving an analog input signal and a row address signal, wherein in response to the row address signal the selection circuit selects a row line to apply the analog input signal;
• a sense circuit coupled to the second array, wherein the sense circuit generates a digital signal, the digital signal depending on which of the memory cells in the second array conducts when the first analog signal is applied;
• a second selection circuit coupled to the column lines in the second array, the selection circuit receiving the digital signal, wherein in response to the digital signal the selection circuit selects a column line that corresponds to the data value;
• and
• a read circuit coupled to read a memory cell that is in the second array and coupled to the column line that the selection circuit selects, the read circuit generating an analog output signal representing the threshold voltage of the memory cell read, wherein the analog output signal is different than the analog input signal.