Apparatus and Method for Digital to Analog Conversion with Current Mirror Amplification

摘要

A DAC using current mirrors suitable for use in a modulator. Embodiments include a current-generating circuit to provide an information signal; a bias current source; a current mirror having a mirror input transistor connected to the current generating circuit and the bias current source, and being driven by the bias current and the varying current signal and having a corresponding varying voltage signal at a control terminal; a signal shaping filter interposed between the mirror input transistor and an output mirror transistor configured to limit a bandwidth of the varying voltage signal; the output mirror transistor configured to generate a band-limited varying current signal and a mirrored bias current; and, a mirrored bias current reduction circuit connected to the output mirror transistor configured to reduce the mirrored bias current.

主权项

1. A method comprising:
generating a varying current signal that is proportional to a varying input signal, at a current-generating circuit; generating a bias current, at a bias current source; driving a mirror input transistor of a current mirror with the bias current and the varying current signal; generating a corresponding varying voltage signal at a control terminal of the mirror input transistor; limiting a bandwidth of the varying voltage signal with a signal shaping filter that is interposed between the mirror input transistor and an output mirror transistor of the current mirror; generating a band-limited varying current signal and a mirrored bias current, at the output mirror transistor; and, reducing the mirrored bias current, at a mirrored bias current reduction circuit that is connected to the output mirror transistor.