Current steering semi-digital reconstruction filter

A method of converting a 1-bit digital input signal to an analog output signal, comprising the steps off

• (a) inputting said 1-bit digital input signal to a shift register;
• (b) shifting said 1-bit signal through said shift register;
• (c) providing, as a control bit, said shifted 1-bit signal to a plurality of output taps disposed along said shift register, wherein said control bit has a value of either a logic 1 or a logic 0;
• (d) controlling a plurality of non-inverted current switches and inverted current switches with said bit-values of said shift register output taps, wherein a single output tap value controls a single pair of switches comprised of a single non-inverted current switch and a single inverted current switch, and wherein said plurality of non-inverted current switches and inverted current switches are connected to a common current source;
• (e) producing a differential current from said plurality of non-inverting current switches and inverting current switches;
• and
• (f) inputting said differential current to a first and a second op amp circuit, wherein a differential voltage is output from said first and second op amp circuits.

A method of converting a 1-bit digital input signal to an analog output signal, comprising the steps off

• (a) inputting said 1-bit digital input signal to a shift register;
• (b) shifting said 1-bit signal through said shift register;
• (c) providing, as a control bit, said shifted 1-bit signal to a plurality of output taps disposed along said shift register, wherein said control bit has a value of either a logic 1 or a logic 0;
• (d) producing a differential current at a pair of current summing nodes by using said control bits to open or close switches disposed along a plurality of resistive paths connected to a common reference current source, wherein a DC offset current is subtracted from said differential current;
• and
• (e) inputting said differential current to a current-to-voltage conversion circuit, wherein a differential voltage is output from said current-to-voltage conversion circuit.